Reactivity of allyl anions of allylphosphine-boranes towards electrophiles
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Page 102 Reactivity of allyl anions of allylphosphine-boranes towards electrophiles Marek Stankevi•, Marcin Siek, and K. Micha• Pietrusiewicz* Department of Organic Chemistry, Faculty of Chemistry, Marie Curie-Sk•odowska University, Gliniana 33, 20-614 Lublin, Poland E-mail: kazimierz.pietrusiewicz@poczta.umcs.lublin.pl This paper is dedicated to Prof. William F. Bailey on the occasion of his 65th birthday --- Abstract The reactivity of mesomeric carbanions derived from allylphosphine-boranes varies as a function of electrophile. Small sp3-electrophiles react predominantly at the • carbon atom whereas bulky sp3-electrophiles and carbonyl compounds react mainly at the • carbon. In the case of electron- deficient aldehydes reduction of carbonyl group and formation of the corresponding alcohols is observed. This is attributed to the weakly reducing properties of carbanions derived from allylphosphine-boranes, whose mesomeric form resembles the structure of a modified borohydride. Keywords: Phosphine-boranes, allyl, carbanion, alkylation, reduction --- Introduction The presence of a multiple carbon-carbon bond in close proximity to phosphorus atom provides a wide the spectrum of reactivity for modifying organophosphorus compounds. Those possessing a P-vinyl substituent can be utilised in Michael addition reactions to provide precursors of P-P1 or P-N-type2 ligands. Ruthenium-catalysed metathesis of vinylphosphine oxides and boranes has been used by several research groups for the synthesis of ethylene-bridged diphosphine derivatives.3 The Diels-Alder reaction between vinyl-substituted organophosphorus compounds and P-heterocycles in the presence of an organometallic template can also provide norbornene- like bicyclic diphosphines.4 In the case of allyl-substituted organophosphorus compounds, most of the known functionalisation chemistry concerns the • -carbanions which are formed upon abstraction of a proton from the allyl moiety by a strong base. When such anions are generated from triphenylphosphonium salts, reaction with carbonyl compounds leads to the formation of a conjugated alkene through a Wittig reaction, and its reactivity has been widely explored in the
Page 103 synthesis of natural compounds like callystatin A,5 astaxanthin analogues,6 ratjadone,7 epolactaene,8 viridenomycin9 or superstolide A.10 In such cases, however, the loss of the phosphorus moiety is necessary to complete the synthesis. In the cases where the phosphorus moiety is retained in the final product, the mesomeric nature of phosphorus-substituted allyl anion means that the formation of two isomeric compounds is to be expected (Scheme 1). Scheme 1. Mesomeric forms of allyl anion derived from P-allyl compounds. The outcome of such a reaction is influenced by the nature of the substrates employed and the reaction conditions, with less sterically demanding electrophiles generally preferring the • -position, whilst more sterically encumbered electrophiles favour the • -position. Results obtained so far for allylphosphonates show that sp3-electrophiles and aldehydes react preferentially at the • -position11 whereas ketones react at both the • - and the • -carbon.12 On the other hand, • ,• -unsaturated carbonyls react mainly at the • -carbon atom of the allyl moiety.13 Surprisingly little is known about the reactivity of other classes of allyl-substituted organophosphorus compounds,14 including phosphine-boranes, which are very attractive substitutes for free phosphines because they are devoid of many typical shortcomings of free phosphines such as sensitivity to oxygen and moisture. These features explain why phosphine- boranes are often used in the synthesis of phosphine ligands for transition metal-catalysed reactions.15 Surprisilgly, the only known application of phosphine-borane-derived allyl carbanions can be found in one of our recent studies,16 which demonstrated that the alkylation of a 3-phospholene-borane with dihaloalkanes in the presence of an excess of base can lead to the formation of a bicyclic phosphine-borane as the major reaction product (Scheme 2) Scheme 2. Cyclopentannulation of 1-phenylphosphol-3-ene-borane.
Page 104 The usefulness and generality of these allyl anion-induced annulations was further confirmed by the synthesis of P,C-chiral bicyclic monophosphine ligands which showed enantioselectivities up to 95% ee in palladium-catalysed allylic substitution reactions.17 The structural complexity of the bicyclic phosphine-borane formed from simple allylphosphine-boranes nicely illustrates the ambivalent reactivity of phosphorus-substituted allyl anions and suggests that, if controlled appropriately, this could be used in the synthesis of a wide range of useful compounds. To achieve this, a basic understanding of the reactivity of such systems is needed. Here, we present our results concerning the reactivity of allyl carbanions derived from allyphosphine-boranes or phosphol-3-ene-boranes. Results and Discussion Three model phosphine-boranes: allyl-t-butylphenylphosphine-borane 1a, allyldiphenyl- phosphine-borane 1b and 1-phenylphosphol-3-ene-borane 1c (Chart 1), were chosen for test reactions because they present different structural motifs having diaryl, arylalkyl and arylcycloalkyl substitution patterns at phosphorus. Chart 1. Model phosphine-boranes. Allyl-t-butylphenylphosphine-borane 1a was synthesized in three steps from phenyldichlorophosphine as shown in Scheme 3. Scheme 3. The synthesis of allyl(t-butyl)phenylphosphine-borane 1a. Treatment of PhPCl2 with t-butyl chloride in the presence of AlCl3 followed by hydrolysis gave t-butylphenylphosphinic chloride. Subsequent reduction with LiAlH4 and in situ trapping with BH3 afforded the corresponding secondary phosphine-borane, which was in turn allylated in the presence of butyllithium.
Page 105 Allyldiphenylphosphine-borane 1b was prepared in three steps starting from commercially available triphenylphosphine (Scheme 4). Scheme 4. The synthesis of allyldiphenylphosphine-borane 1b. Triphenylphosphine was treated with the BH3-THF complex to give the corresponding phosphine-borane quantitatively. Removal of one phenyl group from the phosphorus atom was accomplished by treatment with sodium and the resulting secondary phosphine-borane was converted to allylphosphine-borane by allylation with BuLi/Allyl-Cl. 1-Phenylphosphol-3-ene-borane 1c was prepared from the corresponding phosphine oxide in two steps16b through reduction of P=O bond with LiAlH4 and in situ complexation of tertiary phosphine with BH3-THF. With these three model compounds in hands, we started our studies of the alkylation of P- allyl carbanions with a range of alkyl halides (Table 1). Table 1. Reactivity of 1a-b towards alkylating agents Entry Electrophile Phosphine- borane Products (%) 1 MeI (a) 1a 2aa 68 3aa 15 2 1b 2ba 88 - 3 BnCl (b) 1a 2ab 29* 3ab 21 4 1b 2bb 76 3bb 13 5 AllylCl (c) 1a 2ac 13 3ac 62 6 1b 2bc 42 3bc 42 7 c-HexBr (d) 1a - 3ad 47 8 1b 2bd 22 3bd 47 9 TMSCl (e) 1a - 3ae 91 10 BrCH2COOEt (f) 1a - 3af 20 11 BrCH2COOEt (f) 1a 2af 23** - * - when performed in Et2O, the reaction afforded 2ab as the sole product in 58% yield. ** - the reaction was performed at 0 oC.
Page 106 It can be seen from Table 1 that only methyl iodide, the smallest electrophile, gave completely regioselective alkylation at the • -carbon of the P-allyl carboanion (entries 1 and 2, Table 1). Other electrophiles react with phosphine-boranes 1a and 1b at both the • - and • - carbanionic sites. The course of the reaction seems to be governed by the steric hindrance at the reaction centre; this control is more pronounced for 1a which possesses a bulky tert-butyl group attached to the phosphorus atom than for 1b which features a smaller phenyl substituent. Steric crowding at the phosphorus atom impedes the approach of the electrophile at the • -carbon atom thus favouring its reaction through the • -carbocation. This is clearly seen in the reactions of 1a with different electrophiles (entries 1,3,5,7,9), where replacement of methyl iodide with the more bulky benzyl chloride gives less clean • -alkylation and no • -alkylation at all is found when cyclohexyl bromide or trimethylsilyl chloride are used as electrophiles. An interesting effect was observed in the reaction of 1a with ethyl bromoacetate. When performed at -78 oC, the reaction afforded the • -alkylation product 3af in 20% yield (Table 1, entry 10) whilst changing the temperature to 0 oC gave only • -alkylation product 2af in 23% yield (Table 1, entry 11). Being sterically less demanding than a t-butyl substituent, the phenyl group gives higher yields of • -alkylation products (entries 2,4,6,8, Table 1). Even with cyclohexyl bromide the formation of • -alkylation product was still observed at a reasonable level. Unlike 1a and 1b, phosphine-borane 1c gave only • -alkylation products, regardless of the electrophile used. Another striking observation for 1c was the formation of bis-• ,• ’-alkylated products in the reaction with benzyl and allyl chlorides (Scheme 5). THF, -78 oC to rt, 2.5 h1. BuLi (1.2 equiv.) 2. Alkyl halide (2 equiv). PPhBH3AlkAlkPPhBH3+PPhBH3Alk1cMeI (a) BnCl (b) AllylCl (c) c-HexBr (d) 2ca (48%) - 2cc (51%) - 4cb (74%) 4cc (25%) No reaction Scheme 5. Reaction of 1c with various alkyl halides. The same type of behaviour has previously been observed by Pakulski et al. in the reactions of 3-phospholene oxides and sulphides with alkylating agents (Scheme 2).16 Another potentially useful application of P-allyl anions is their homocoupling, which provides diphosphines having two double bonds in the carbon skeleton linking the two phosphorus atoms. Given the two mesomeric forms of phosphorus-substituted allyl anion, three isomeric • ,• -, • ,• - and • ,• - coupling products 5, 6 or 7 can theoretically be formed (Scheme 6). Each of them appears to have a potentially useful unsaturation pattern: activated double bonds for Michael addition or Diels-Alder reaction in 5, or non-activated allylic double bonds for radical reactions or polymerisation in 6 and 7. In the event, treatment of the allyl anion generated from phosphine-
Page 107 borane 1a and LDA with CuCl2 or FeCl3 led to the formation of only the • ,• -coupled product in 20% and 66% yields, respectively (Scheme 6). Scheme 6. Homocoupling of 1a. We next turned our attention to sp2-type electrophiles and explored their reactivity towards the P-allyl anions derived from 1a-c (Table 2). The results collected in the Table 2 clearly show that, under basic conditions, phosphine-boranes 1a,b react as • -carbon nucleophiles towards carbonyl compounds to give the corresponding • -hydroxy-• -alkenylphosphine-boranes 8 exclusively, in good to excellent yields. Formaldehyde however, failed to give clean conversion and instead yielded a complex product mixtures. With acetophenone as the electrophile (Table 2, entry 11), the allyl anion of 1a afforded a mixture of two • -addition products: 8al and 9al, the latter possibly arising from isomerisation of the double bond in 8al. Another striking observation was the reaction of methyl vinyl ketone m with the allyl anions of 1a and 1b (Table 2, entries 13, 14). In this case, the allyl anions reacted exclusively through 1,2-addition to form the corresponding • -alcohols in good yields. This stands in sharp contrast to previous observations of the reactivity of phosphoryl-substituted allyl anions with ••• -unsaturated carbonyl compounds where exclusively 1,4-addition products were observed in the reaction mixture.13 Reactions with methyl vinyl ketone also revealed a sensitivity to steric demands. In the case of allyl-t- butylphenylphosphine-borane 1a, the only product isolated from the reaction mixture resulted from • -addition, whereas in the case of 1b substantial quantities of • -addition product were observed (Table 2, entry 14). With ethyl acetate as the electrophile, the only compound isolated from the reaction mixture was the tertiary alcohol 8an, an evolution product which results from the addition of butyllithium to the carbonyl group of the first-formed • -acyl product (Table 2, entry 15). In the case of borane 1a, addition of the allyl anion to carbonyl compound possessing a prochiral C=O group created additional chirality at the centre • to the phosphorus atom. However, as there was no steric differentiation in the proximity of the • carbon atom, the reaction of 1a with prochiral carbonyl reagents prodeeded with low diatereoselectivity in all cases (Table 2, entries 1, 3, 5, 11 and 13). Addition of carbon dioxide to the allyl anion of 1a,b yielded the corresponding (• - boranatophosphinyl)but-3-enoic acids in 76 and 92% yields, respectively (Table 2, entries 16 and 17).
Page 108 Table 2. Reactivity of 1a-b towards carbonyl compounds Entry Electrophile Phosphine- borane Products (%) 1 benzaldehyde (g) 1a 8ag 97 (61:39 d.r.) 2 1b 8bg 77 3 p-tolulaldehyde (h) 1a 8ah 64 (50:50 d.r.) 4 1b 8bh 65 5 o-tolulaldehyde (i) 1a 8ai 67 (53:47 d.r.) 6 1b 8bi 73 7 acetone (j) 1a 8aj 99 8 1b 8bj 73 9 cyclohexanone (k) 1a 8ak 71 10 1b 8bk 53 11 acetophenone (l) 1a 8al 36 (56:44 d.r.) 9al 24 (62:38 d.r.) 12 1b 8bl 67 13 methyl vinyl ketone (m) 1a 8am 84 (58:42 d.r.) 14 1b 8bm:10bm 91 (45:55) 15 ethyl acetate (n) 1a 8an (R' - Me, R" - n-Bu) 81 16 carbon dioxide (o) 1a 8ao 76 17 1b 8bo 92 Unlike phosphine-boranes 1a and 1b, the cyclic phosphine-borane 1c reacted only as an • -nucleophiles but isomerisation of the double bond was observed in some cases. This may reflect strongly basic conditions present in the reaction mixture (Scheme 7). Scheme 7. Reactivity of 1c towards carbonyl compounds.
Page 109 Interesting results were obtained in the reaction between P-allyl anions derived from 1a and 1b and methyl chloroformate (Scheme 8). Scheme 8. Reaction of 1a with methyl chloroformate. In both cases, the formation of • ,• -disubstitution products was observed, in 40% and 86% yields for 1a and for 1b, respectively. It seems likely, that the formation of these unusual products can be explained in terms of an enhanced reactivity of the intermediate monosubstitution product with respect to the parent P-allyl anion. An interesting feature of the reactions of allylphosphine-borane anions with some electron deficient carbonyl electrophiles was the reduction of the carbonyl compounds (Scheme 9). Scheme 9. Reaction of 1a with nitro-substituted benzaldehydes under basic conditions. In the reaction of 1a with p-nitrobenzaldehyde the yield of the expected adduct 8ap was only 18% (1H NMR) while the yield of p-nitrobenzyl alcohol 12p was 26% based on consumed aldehyde. When o-nitrobenzaldehyde was used as the reactant, the yield of expected 8aq was estimated to be 36% (1H NMR), whereas the yield of o-nitrobenzyl alcohol 12q was 29% as based on aldehyde consumption. The formation of such benzyl alcohols in reactions, where no reducing agent was added to the reaction mixture, points to the allylphosphine-borane anions as potential reducing agents.
Page 110 Scheme 10. Formulation of an allylphosphine-borane anion as amodified lithium borohydride. As depicted in Scheme 10, deprotonation of allylphosphine-borane leads to the formation of an anion whose structure can be drawn in three mesomeric forms 15-17. Form 17 localises some anionic electron density at boron and can be regarded as a modified borohydride anion. Borohydrides are known to reduce carbonyl groups in aldehydes and ketones easily but is apparently less reactive and exhibits its reducing properties only towards electron deficient aldehydes (Scheme 11). Scheme 11. Plausible mechanism for the reduction of carbonyl groups by a modified borohydride. Conclusions In conclusion, the reactivity of mesomeric allylphosphine-borane-derived anions derived from allylphosphine-boranes towards electrophiles depends strongly on the structure of the starting allylphosphine-borane and on the electrophile. Small sp3-electrophiles react predominantly at the • -carbon atom, whereas sterically demanding sp3-electrophiles react mostly at the • -carbon. On the other hand, sp2-electrophiles react with such allyl anions at • -carbon atom to give • -hydroxy- • -alkenylphosphine-boranes in good yields, except in the case of electron deficient carbonyl compounds which are reduced by the phosphine-borane anions to the corresponding alcohols instead of being attacked by the allyl anion. Homodimerisation of allylphosphine-borane-derived anions provides 1,6-diphosphine-diboranes possessing a 1,5-hexadienyl linker.
Page 111 Experimental Section General. All reactions were conducted under inert atmosphere and with anhydrous and oxygen- free solvents. THF was dried under sodium/benzophenone, diethyl ether was dried under metallic sodium and chloroform was dried under P2O5. All electrophiles used in reactions were commercially available and were used as received. The course of reaction was followed by TLC (Merck, silica 60 F254, aluminium plates) and iodine/SiO2 was used as the developing agent. Flash chromatography was performed using silica gel (Merck, 20-230 mesh) with hexane:ethyl acetate 2-50:1 as eluents. NMR analyses were performed on Bruker Avance 300 in CDCl3 with TMS as internal standard and elementary analysis was performed on PERKIN ELMER CHN 2400 at the Department of Organic Chemistry, Marie Curie-Sk•odowska University, Lublin, Poland. Synthesis of allyl-t-butylphenylphosphine-borane (1a) t-Butylphenylphosphinic chloride. In a two-necked flask (500 mL) equipped with magnetic stirrer, argon inlet and dropping funnel was placed 200 mL of chloroform, 23 mL (0.17 mol) dichlorophosphine, and 25 g (0.188 mol) of AlCl3 and the mixture was stirred at room temperature for 30 min until all AlCl3 dissolved. Then, the flask was immerced in the ice-water bath and 25 mL (0.226 mol) of t-butyl chloride was slowly added via dropping funnel. After complete addition of t-BuCl the reaction mixture was stirred at room temperature for overnight. Then, diluted hydrochloric acid (10%, 150 mL) was added and mixture was extracted with DCM (5x100 mL). Combined organic phases were dried over magnesium sulfate, filtered and evaporated and the residue was distilled under low pressure yielding t-butylphenylphosphinic chloride as colorless oil which solidified upon standing in refrigerator (24.3 g, 66%). b.p. 156 oC/15 mm Hg. 1H NMR (CDCl3, 300 MHz): • 1.26 (d, JP-H 19.1 Hz, t-Bu, 9H), 7.45-7.70 (m, Ph, 3H), 7.79-7.96 (m, Ph, 2H); 13C NMR (CDCl3, 75 MHz): • 24.12, 38.93 (d, JP-C 77.4 Hz), 128.25 (d, JP-C 12.8 Hz), 132.45 (d, JP-C 10.0 Hz), 132.81 (d, JP-C 2.9 Hz). 31P NMR (CDCl3, 121.5 MHz): • 74.3 ppm. Elem. anal. for C10H14ClOP: calc. C 55.44, H 6.51; found C 55.59, H 6.82. t-Butylphenylphosphine-borane. In a 500 mL two-necked flask equipped with magnetic stirrer, ice-water bath and argon inlet was placed 150 mL of diethyl ether and 2.40 g (11 mmol) of t- butylphenylphosphinic chloride. Reaction mixture was cooled to 0 oC and 0.84 g (22 mmol) of lithium aluminum hydride was added in one portion and reaction was stirred at 0 oC for two hours. Then, excess of LiAlH4 was removed by slow addition of water until no bubbling was observed. The formed solids were removed by filtration through 2 cm layer of silica gel under argon and the solid was washed with DCM (100 mL). The solution was then placed in the two- necked flask equipped with magnetic stirrer and argon inlet and 22 mL (22 mmol) of 1M BH3- THF complex was added. Reaction was stirred at room temperature for an hour and then was evaporated and the residue was dissolved in 50 mL of DCM and filtered. Evaporation yielded 1.98 g (100%) of t-butylphenylphosphine-borane as colorless oil. 1H NMR (CDCl3, 300 MHz): • –0.05-1.65 (bm, BH3, 3H); 1.21 (d, JP-H 14.8 Hz, t-Bu, 9H), 5.13 (dq, JP-H 368.0 Hz, 1H, P-H);
Page 112 7.41-7.73 (m, 5H, Ph). 13C NMR (CDCl3, 75 MHz): • 26.54 (d, JP-C 2.9 Hz), 28.46 (d, JP-C 32.5 Hz), 124.74 (d, JP-C 51.0 Hz), 128.54 (d, JP-C 9.7 Hz). 131.50 (d, JP-C 3.5 Hz), 133.88 (d, JP-C 7.7 Hz). 31P NMR (CDCl3, 121.5 MHz): • 31.99 ppm (m). Elem. anal. for C10H15BP: calc. C 66.83, H 10.21; found C 67.15, H 10.48. Allyl-t-butylphenylphosphine-borane (1a). In a 250 mL two-necked flask equipped with magnetic stirrer, dry ice-acetone bath, and argon inlet was placed 100 mL of THF and 1.98 g (11 mmol) of t-butylphenylphosphine-borane. Then, 10 mL (16.5 mmol) of 1.6 M butyllithium was added and mixture was stirred at -78 oC for 30 minutes. Then, 1.8 mL (22 mmol) of allyl chloride was added and reaction mixture was left at room temperature for overnight. Then, 10 mL of 5% HCl was added with subsequent 30 mL of distilled water and the mixture was extracted with DCM (3x50 mL). Organic phases were dried over magnesium sulfate, filtered and evaporated. The residue was purified by flash chromatography using hexane/EtOAc 6:1 as eluent yielding 2.0 g (83%) of allyl-t-butylphenylphosphine-borane 1a as pasty white solid. 1H NMR (CDCl3, 300 MHz): • 0.13-1.29 (bm, BH3, 3H), 1.12 (d, JP-H 13.7 Hz, t-Bu, 9H), 2.72-2.86 (m, 1H), 2.88-3.04 (m, 1H), 5.05-5.21 (m, 2H), 7.40-7.53 (m, 3H), 7.66-7.75 (m, 2H). 13C NMR (CDCl3, 75 MHz): • 24.74 (d, JP-C 33.1 Hz), 25.04 (d, JP-C 2.3 Hz), 28.89 (d, JP-C 30.8 Hz), 119.18 (d, JP-C 10.6 Hz), 125.19 (d, JP-C 48.3 Hz), 127.76 (d, JP-C 9.2 Hz), 128.76 (d, JP-C 4.6 Hz), 130.73 (d, JP-C 2.3 Hz), 133.16 (d, JP-C 7.6 Hz). 31P NMR (CDCl3, 121.5 MHz): • 30.36 (m). Elem. anal. for C13H19BP: calc. C 70.93, H 10.09; found C 70.18, H 10.01. Synthesis of allyldiphenylphosphine-borane (1b) Diphenylphosphine-borane. In a 250 mL two-necked flask equipped with magnetic stirrer and argon inlet was placed 100 mL of THF, 10 g (38 mmol) of triphenylphosphine and 38 mL (38 mmol) of 1M BH3-THF was added. After one hour the mixture was evaporated yielding pure triphenylphosphine-borane which was used directly in the next step. In 250 mL two-necked flask equipped with magnetic stirrer and argon inlet was placed 100mL of THF, 5.0 g (18 mmol) of triphenylphosphine-borane and 0.83 g (36 mmol) of metallic sodium was added. After stirring for 24h at rt reaction was finished by adding saturated ammonium chloride solution (50 mL). The formed mixture was extracted with DCM (3x100 mL) dried over anhydrous magnesium sulfate, filtered and evaporated. The residue was purified on silica gel using hexane/EtOAc 6:1 as eluent yielding 5.02 g (66%) of diphenylphosphine-borane as colorless oil. 1H NMR (CDCl3, 300 MHz): • 0.25-1.95 (bm, BH3, 3H), 6.35 (dq, JP-H 380.0 Hz, 1H), 7.41-7.79 (m, 10H). 13C NMR (CDCl3, 75 MHz): • 126,11 (d, JP-C 56.9 Hz), 128.98 (d, JP-C 10.6 Hz), 131.56 (d, JP-C 2.4 Hz). 132.85 (d, JP-C 9.3 Hz, P-Ph). 31P NMR (CDCl3, 121.5 MHz): d 2.89 (m). Elem. anal. for C12H14BP: calc. C 71.93, H 6.90; found C 72.15, H 7.09. Preparation of allyldiphenylphosphine-borane (1b). In a Schlenk flask equipped with magnetic stirrer and argon inlet was placed diphenylphosphine-borane (2.34g, 11.7 mmol) in 80 mL of dry THF. Then, reaction was cooled to -78 oC and 1.6 M BuLi (11 mL, 17.6 mmol) was added and the mixture was stirred at -78 oC for 0.5 h. Then, the bath was taken out and allyl chloride(1.91 mL, 22 mmol) was added and the mixture was allowed to stir for overnight. Then,
Page 113 reaction mixture was quenched with saturated ammonium chloride solution and extracted three times with DCM (3x30 mL). Combined organic phases were dried over anhydrous magnesium sulfate, filtered and evaporated to dryness. The residue was purified by flash chromatography using hexane/EtOAc 6:1 as eluent yielding allyldiphenylphosphine-borane 1b (2.20 g, 78%) as colorless oil. 1H NMR (CDCl3, 300 MHz): • 0.30-1.40 (bm, BH3, 3H); 3.04-3.13 (m, 2H), 5.03- 5.11 (m, 2H), 5.72-5.89 (m, 1H), 7.42-7.55 (m, 6H), 7.65-7.74 (m 4H). 13C NMR (CDCl3, 75 MHz): 26.18 (d, JP-C 40.2 Hz), 120.02 (d, JP-C 11.5 Hz), 128.18 (d, JP-C 9.8 Hz), 128.99 (d, JP-C 5.5 Hz), 129.36 (d, JP-C 54.6 Hz), 130.74 (d, JP-C 2.6 Hz), 133.05 (d, JP-C 8.3 Hz). 31P NMR (CDCl3, 121.5 MHz): • 15.88 (m). Elem. anal. for C15H18BP: calc. C 75.04, H 7.56; found C 74.80, H 7.27. General procedure for reaction between allylphosphine-boranes 1 and sp3 electrophiles In a Schlenk flask equipped with magnetic stirrer and argon inlet was placed allylphosphine- borane 1 (0.19-0.76 mmol) in 10 mL of dry THF. Then, reaction was cooled to -78 oC and BuLi (1.6 M in hexanes) (0.28-1.142 mmol) was added and the resulting mixture was stirred at -78 oC temperature for 0.5 h. Then, an electrophile (0.38-1.52 mmol) was added and the reaction mixture was allowed to warm to room temperature overnight. Then, the reaction was quenched with saturated NH4Cl solution and extracted with DCM (3x15 mL). Combined organic phases were dried over anhydrous magnesium sulfate, filtered and evaporated to dryness. The residue was purified by flash chromatography using hexane/EtOAc 2:1 to 50:1 as eluent to give product. (But-1-en-3-yl)-t-butylphenylphosphine-borane (2aa). Yield 68% from 0.076 g (0.35 mmol) of 1, purified with hexane/EtOAc (10/1), white solid, m.p. 42-44 oC. 1H NMR (CDCl3, 300 MHz): • 0.02-1.11 (bm, BH3, 3H), 0.97 (d, JP-H 7.0 Hz, 3H, CH3), 1.04 (d, JP-H 13.5 Hz, 9H, t- Bu), 3.17-3.35 (m, 1H), 5.07-5.14 (m, 1H), 5.17-5.27 (m, 1H), 5.99-6.20 (m, 1H), 7.30-7.45 (m, 3H), 7.62-7.73 (m, 2H). 13C NMR (CDCl3, 75 MHz): • 17.22, 26.15 (d, JP-C 2.0 Hz), 30.36 (d, JP- C 30.2 Hz), 32.39 (d, JP-C 31.9 Hz), 116.70 (d, JP-C 10.4 Hz), 126.90 (d, JP-C 48.0 Hz), 128.26 (d, JP-C 8.9 Hz), 130.97 (d, JP-C 2.3 Hz), 133.23 (d, JP-C 7.2 Hz), 138.01. 31P NMR (CDCl3, 121.5 MHz): • 37.80 (m). Elem. anal. for C14H24BP: calc. C 71.82, H 10.33; found C 71.99, H 10.50. (But-1-en-1-yl)-t-butylphenylphosphine-borane (3aa). Yield 15% from 0.076 g (0.35 mmol) of 1a, purified with hexane/EtOAc (10/1), colorless oil. 1H NMR (CDCl3, 300 MHz): • 0.10- 1.17 (bm, BH3, 3H), 1.08 (d, JP-H 13.7 Hz, 9H, t-Bu), 1.09 (t, JH-H 6.9 Hz, 1H), 2.25-2.35 (m, 2H), 6.16-6.26 (m, 1H), 6.78-7.00 (m, 1H), 7.43-7.53 (m, 3H), 7.69-7.76 (m, 2H). 13C NMR (CDCl3, 75 MHz): • 12.28 (d, JP-C 1.2 Hz), 25.33 (d, JP-C 2.9 Hz), 27.96 (d, JP-C 36.5 Hz), 35.16 (d, JP-C 14.7 Hz), 112.47 (d, JP-C 56.0 Hz), 128.08 (d, JP-C 9.5 Hz), 130.71 (d, JP-C 2.6 Hz), 133.00 (d, JP-C 7.8 Hz), 156.32 (d, JP-C 9.2 Hz). 31P NMR (CDCl3, 121.5 MHz): • 24.83 (m). Elem. anal. for C14H24BP: calc. C 71.82, H 10.33; found C 71.78, H 10.61. (But-1-en-3-yl)-diphenylphosphine-borane (2ba). Yield 88% from 0.077 g (0.32 mmol) of 1b, purified with hexane/EtOAc (6/1), colorless oil. 1H NMR (CDCl3, 300 MHz): • 0.24-1.32 (bm, BH3, 3H), 1.18 (dd, JH-H 7.0 Hz, JP-H 16.28 Hz, CH3, 3H), 3.13-3.32 (m, 1H), 4.84-5.01 (m, 2H), 5.65-5.82 (m, 1H), 7.23-7.43 (m, 6H), 7.60-7.72 (m, 4H). 13C NMR (CDCl3, 75 MHz): 14.33 (d,
Page 114 JP-C 1.5 Hz), 34.89 (d, JP-C 34.5 Hz), 117.76 (d, JP-C 10.1 Hz), 127.90 (d, JP-C 54.0 Hz), 128.26 (d, JP-C 50.9 Hz), 128.42 (d, JP-C 9.8 Hz), 128.70 (d, JP-C 10.1 Hz), 131.10 (d, JP-C 2.3 Hz), 131.12 (d, JP-C 2.0 Hz), 132.58 (d, JP-C 8.3 Hz), 133.00 (d, JP-C 8.3 Hz), 135.15 (d, JP-C 2.9 Hz). 31P NMR (CDCl3, 121.5 MHz): • 23.29 (m). Elem. anal. for C16H20BP: calc. C 75.62, H 7.93; found C 75.80, H 7.95. 2-Methyl-1-phenyl-3-phospholene-borane (2ca). Yield 48% from 0.050 g (0.28 mmol) of 1c, purified with hexane/EtOAc (6/1), colorless oil. 1H NMR (CDCl3, 300 MHz): • 0.13-1.32 (bm, BH3, 3H), 1.27 (dd, JP-H 16.7 Hz, JP-H 7.3 Hz, CH3, 3H), 2.61-2.88 (m, 2H), 2.90-3.03 (m, 1H), 5.79-5.92 (m, 2H), 7.31-7.46 (m, 3H), 7.61-7.70 (m, 2H). 13C NMR (CDCl3, 75 MHz): • 16.04 (d, JP-C 4.9 Hz), 32.86 (d, JP-C 35.6 Hz), 39.62 (d, JP-C 34.5 Hz), 126.73 (d, JP-C 0.9 Hz), 128.77 (d, JP-C 9.8 Hz), 131.10 (d, JP-C 8.6 Hz), 131.35 (d, JP-C 2.6 Hz), 131.38 (d, JP-C 52.3 Hz), 135.98 (d, JP-C 4.9 Hz). 31P NMR (CDCl3, 121.5 MHz): • 32.20 (m). Elem. anal. for C11H16BP: calc. C 69.52, H 8.49; found C 69.40, H 8.40. t-Butylphenyl-(4-phenylbut-1-en-3-yl)phosphine-borane (2ab). Yield 29% from 0.051 g (0.23 mmol) of 1a, purified with hexane/EtOAc (10/1), colorless oil. 1H NMR (CDCl3, 300 MHz): • 0.11-1.28 (bm, BH3, 3H), 1.06 (d, JP-H 13.6 Hz, t-Bu, 9H), 2.44-2.66 (m, 2H), 3.15-3.30 (m, 1H), 4.74-4.83 (m, 1H), 5.03-5.09 (m, 1H), 5.91-6.07 (m, 1H), 6.85-6.91 (m, 2H), 7.04-7.19 (m, 3H), 7.41-7.50 (m, 3H), 7.77-7.85 (m, 2H). 13C NMR (CDCl3, 75 MHz): • 26.20 (d, JP-C 1.7 Hz), 30.69 (d, JP-C 29.6 Hz), 36.23 (d, JP-C 2.3 Hz), 40.95 (d, JP-C 30.8 Hz), 119.51 (d, JP-C 10.9 Hz), 126.19, 126.98 (d, JP-C 47.7 Hz), 128.02, 128.54 (d, JP-C 9.2 Hz), 129.20, 131.29 (d, JP-C 2.3 Hz), 133.33 (d, JP-C 7.2 Hz), 134.79, 139.12 (d, JP-C 12.6 Hz). 31P NMR (CDCl3, 121.5 MHz): • 36.96 (m). Elem. anal. for C20H28BP: calc. C 77.43, H 9.10; found C 77.70, H 9.31. t-Butylphenyl-(4-phenylbut-1-en-1-yl)phosphine-borane (3ab). Yield 21% from 0.051 g (0.23 mmol) of 1a, purified with hexane/EtOAc (10/1), colorless oil. 1H NMR (CDCl3, 300 MHz): • 0.07-1.28 (bm, BH3, 3H), 0.95 (d, JP-H 13.9 Hz, t-Bu, 9H), 2.51-2.61 (m, 2H), 2.71-2.79 (m, 2H), 6.01-6.12 (m, 1H), 6.71-6.89 (m, 1H), 7.04-7.15 (m, 3H), 7.15-7.24 (m, 2H), 7.28-7.40 (m, 3H), 7.51-7.60 (m, 2H). 13C NMR (CDCl3, 75 MHz): • 25.31 (d, JP-C 2.6 Hz), 29.45 (d, JP-C 35.4 Hz), 34.29 (d, JP-C 1.4 Hz), 36.75 (d, JP-C 14.7 Hz), 114.82 (d, JP-C 54.9 Hz), 126.04, 128.11 (d, JP-C 9.5 Hz), 128.43, 128.45, 128.90 (d, JP-C 43.7 Hz), 130.73 (d, JP-C 2.6 Hz), 133.03 (d, JP-C 8.3 Hz), 140.71, 153.58 (d, JP-C 9.5 Hz). 31P NMR (CDCl3, 121.5 MHz): • 25,28 ppm (m). Elem. anal. for C20H28BP: calc. C 77.43, H 9.10; found C 77.25, H 9.00. Diphenyl-(4-phenylbut-1-en-3-yl)phosphine-borane (2bb). Yield 76% from 0.081 g (0.33 mmol) of 1b, purified with hexane/EtOAc (50/1), colorless oil. 1H NMR (CDCl3, 300 MHz): • 0.33-1.63 (bm, BH3, 3H), 2.66-2.92 (m, 2H), 3.22-3.37 (m, 1H), 4.49-4.61 (m, 1H), 4.83-4.90 (m, 1H), 5.57-5.74 (m, 1H), 7.00-7.23 (m, 5H), 7.24-7.48 (m, 6H), 7.60-7.71 (m, 2H), 7.75-7.85 (m, 2H). 13C NMR (CDCl3, 75 MHz): • 35.14 (d, JP-C 3.6 Hz), 43.26 (d, JP-C 32.5 Hz), 120.48 (d, JP-C 10.3 Hz), 126.29, 128.03 (d, JP-C 54.3 Hz), 128.06 (d, JP-C 56.0 Hz), 128.20, 128.41 (d, JP-C 9.8 Hz), 128.89 (d, JP-C 10.1 Hz), 128.92, 131.13 (d, JP-C 2.3 Hz), 131.38 (d, JP-C 2.6 Hz), 132.69 (d, JP-C 8.9 Hz), 132.76 (d, JP-C 2.6 Hz), 132.92 (d, JP-C 8.6 Hz), 139.18 (d, JP-C 13.8 Hz). 31P
Page 115 NMR (CDCl3, 121.5 MHz): • 21.96 (m). Elem. anal. for C22H24BP: calc. C 80.02, H 7.33; found C 79.91, H 7.14. Diphenyl-(4-phenylbut-1-en-1-yl)phosphine-borane (3bb). Yield 13% from 0.081 g (0.33 mmol) of 1b, purified with hexane/EtOAc (50/1), colorless oil. 1H NMR (CDCl3, 300 MHz): • 0.33-1.63 (bm, BH3, 3H), 2.23-2.34 (m, 2H), 2.60-2.71 (m, 2H), 6.02-6.15 (m, 1H), 6.57-6.76 (m, 1H), 7.05-7.27 (m, 5H), 7.34-7.48 (m, 6H), 7.61-7.77 (m, 4H). 13C NMR (CDCl3, 75 MHz): • 34.20 (d, JP-C 1.2 Hz), 36.44 (d, JP-C 15.2 Hz), 119.40 (d, JP-C 57.8 Hz), 126.05, 128.16, 128.62 (d, JP-C 10.1 Hz), 128.49, 130.90 (d, JP-C 2.3 Hz), 132.32 (d, JP-C 9.5 Hz), 151.77 (d, JP-C 7.5 Hz). 31P NMR (CDCl3, 121.5 MHz): • 13.35 (m). Elem. anal. for C22H24BP: calc. C 80.02, H 7.33; found C 80.24, H 7.50. 2,5-Dibenzyl-3-phospholene-borane (4cb). Yield 73% from 0.051 g (0.29 mmol) of 1c, purified with hexane/EtOAc (50:1), white solid, m.p. 100-102 oC. 1H NMR (CDCl3, 300 MHz): • 0.12-1.63 (bm, BH3, 3H), 2.57-2.72 (m, 2H), 3.08-3.31 (m, 4H), 5.65-5.79 (m, 2H), 7.04-7.28 (m, 15H). 13C NMR (CDCl3, 75 MHz): • 38.08 (d, JP-C 5.2 Hz), 46.62 (d, JP-C 32.2 Hz) 126.38, 128.24, 128.44, 128.83, 128.84 (d, JP-C 9.5 Hz), 131.20 (d, JP-C 8.6 Hz), 131.26 (d, JP-C 48.6 Hz), 131.49 (d, JP-C 2.3 Hz), 132.60 (d, JP-C 4.3 Hz), 139.97 (d, JP-C 13.5 Hz). 31P NMR (CDCl3, 121.5 MHz): • 38.66 (m). Elem. anal. for C24H26BP: calc. C 80.91, H 7.36; found C 80.92, H 7.50. t-Butyl-(hexa-1,5-dien-3-yl)phenylphosphine-borane (2ac). Yield 13% from 0.148 g (0.76 mmol) of 1a, purified with hexane/EtOAc (10/1), colorless oil. 1H NMR (CDCl3, 300 MHz): • 0.07-1.20 (bm, BH3, 3H), 1.04 (d, JP-H 13.7 Hz, t-Bu, 9H), 1.81-1.95 (m, 1H), 2.07-2.22 (m, 1H), 3.00-3.14 (m, 1H), 4.72-4.91 (m, 2H), 5.12-5.25 (m, 2H), 5.48-5.64 (m, 1H), 5.86-6.02 (m, 1H), 7.31-7.47 (m, 3H), 7.62-7.74 (m, 2H). 31P NMR (CDCl3, 121.5 MHz): • 36.69 (m). Elem. anal. for C16H26BP: calc. C 73.87, H 10.07; found C 74.15, H 10.34. t-Butyl-(hexa-1,5-dien-1-yl)phenylphosphine-borane (3ac). Yield 62% from 0.148 g (0.76 mmol) of 1a, purified with hexane/EtOAc (10/1), colorless oil. 1H NMR (CDCl3, 300 MHz): • 0.08-1.23 (bm, BH3, 3H), 1.02 (d, JP-H 14.0 Hz, t-Bu, 9H), 2.13-2.23 (m, 2H), 2.29-2.39 (m, 2H), 4.90-5.03 (m, 2H), 5.64-5.81 (m, 1H), 6.10-6.22 (m, 1H), 6.69-6.87 (m, 1H), 7.29-7.45 (m, 3H), 7.60-7.72 (m, 2H). 13C NMR (CDCl3, 75 MHz): • 25.36 (d, JP-C 2.9 Hz), 29.36 (d, JP-C 35.1 Hz), 32.10 (d, JP-C 1.2 Hz), 34.39 (d, JP-C 14.9 Hz), 114.28 (d, JP-C 55.8 Hz), 115.54, 128.11 (d, JP-C 9.5 Hz), 128.30 (d, JP-C 52.6 Hz), 130.77 (d, JP-C 2.3 Hz), 133.06 (d, JP-C 8.3 Hz), 137.13, 153.97 (d, JP-C 8.9 Hz). 31P NMR (CDCl3, 121.5 MHz): • 25.19 (m). Elem. anal. for C16H26BP: calc. C 73.87, H 10.07; found C 73.99, H 10.00. (Hexa-1,5-dien-3-yl)diphenylphosphine-borane (2bc). Yield 42%, from 0.072 g (0.30 mmol) of 1b, purified with hexane/EtOAc (6/1), colorless oil. 1H NMR (CDCl3, 300 MHz): • 0.30-1.58 (bm, BH3, 3H), 2.11-2.20 (m, 2H), 3.02-3.18 (m, 1H), 4.72-5.04 (m, 2H), 5.52-5.79 (m, 1H), 5.98-6.13 (m, 1H), 6.44-6.64 (m, 1H), 7.26-7.45 (m, 6H), 7.58-7.75 (m, 4H). 13C NMR (CDCl3, 75 MHz): • 33.04 (d, JP-C 3.2 Hz), 41.01 (d, JP-C 33.9 Hz), 115.60, 119.94 (d, JP-C 10.6 Hz), 128.39 (d, JP-C 9.8 Hz), 128.80 (d, JP-C 10.1 Hz), 130.00 (d, JP-C 59.2 Hz), 131.11 (d, JP-C 2.3 Hz), 131.27 (d, JP-C 2.3 Hz), 132.60 (d, JP-C 8.6 Hz), 132.94 (d, JP-C 8.6 Hz), 133.09 (d, JP-C 2.9 Hz),
Page 116 135.50 (d, JP-C 14.1 Hz). 31P NMR (CDCl3, 121.5 MHz): • 21.99 (m). Elem. anal. for C18H22BP (as a mixture with 3bc): calc. C 77.17, H 7.92; found C 77.30, H 7.80. (Hexa-1,5-dien-1-yl)diphenylphosphine-borane (3bc). Yield 42%, from 0.072 g (0.30 mmol) of 1b, purified with hexane/EtOAc (6/1), colorless oil. 1H NMR (CDCl3, 300 MHz): • 0.30-1.58 (bm, BH3, 3H), 2.01-2.38 (m, 4H), 4.72-5.04 (m, 4H), 5.52-5.79 (m, 2H), 7.26-7.45 (m, 6H), 7.47-7.58 (m, 4H). 13C NMR (CDCl3, 75 MHz): • 32.04 (d, JP-C 1.2 Hz), 34.00 (d, JP-C 15.2 Hz), 116.74, 118.87 (d, JP-C 58.3 Hz), 128.07 (d, JP-C 63.2 Hz), 128.67 (d, JP-C 10.1 Hz), 130.96 (d, JP- C 2.6 Hz), 132.35 (d, JP-C 9.8 Hz), 137.01, 152.21 (d, JP-C 7.8 Hz). 31P NMR (CDCl3, 121.5 MHz): • 13.46 (m). Elem. anal. for C18H22BP (as a mixture with 2bc): calc. C 77.17, H 7.92; found C 77.30, H 7.80. 2-Allyl-1-phenyl-3-phospholene-borane (2cc). Yield 51% from 0.051 g (0.29 mmol) of 1c, purified with hexane/EtOAc (50:1), colorless oil. 1H NMR (CDCl3, 300 MHz): • 0.09-1.31 (bm, BH3, 3H), 2.10-2.29 (m, 2H), 2.50-2.69 (m, 2H), 2.84-2.92 (m, ,-CH-P-CH2, 1H), 2.83-3.01 (m, 1H), 4.91-5.06 (m 2H), 5.68-5.86 (m, 1H), 5.86-6.00 (m, 2H), 7.29-7.48 (m, 3H), 7.58-7.72 (m, 2H). 13C NMR (CDCl3, 75 MHz): • 33.04 (d, JP-C 35.9 Hz), 35.39 (d, JP-C 6.0 Hz), 44.79 (d, JP-C 33.6 Hz), 116.85, 127.56 (d, JP-C 0.6 Hz), 128.83 (d, JP-C 9.8 Hz), 131.15 (d, JP-C 8.9 Hz), 131.24 (d, JP-C 48.3 Hz), 131.90 (d, JP-C 2.6 Hz, P-Ph), 133.76 (d, JP-C 5.2 Hz), 135.89 (d, JP-C 11.5 Hz). 31P NMR (CDCl3, 121.5 MHz): • 31.44 (m). Elem. anal. for C13H18BP: calc. C 72.26, H 8.40; found C 72.40, H 8.45. 2,5-Diallyl-1-phenyl-3-phospholene-borane (4cc). Yield 25% from 0.051 g (0.29 mmol) of 1c, purified with hexane/EtOAc (50:1), colorless oil. 1H NMR (CDCl3, 300 MHz): • 0.06-1.27 (bm, BH3, 3H), 2.10-2.27 (m, 2H), 2.50-2.66 (m, 2H), 2.88-3.00 (m, 2H), 4.92-5.05 (m, 4H), 5.67- 5.84 (m, 2H), 5.88-6.01 (m, 2H), 7.31-7.47 (m, 3H), 7.61-7.73 (m, 2H). 13C NMR (CDCl3, 75 MHz): • 35.85 (d, JP-C 4.3 Hz), 44.75 (d, JP-C 33.1 Hz), 116.86, 128.83 (d, JP-C 9.5 Hz), 131.23 (d, JP-C 8.6 Hz), 131.41 (d, JP-C 2.6 Hz), 131.51 (d, JP-C 48.9 Hz), 132.62 (d, JP-C 4.3 Hz), 135.85 (d, JP-C 11.5 Hz). 31P NMR (CDCl3, 121.5 MHz): • 38.54 (m). Elem. anal. for C16H22BP: calc. C 75.03, H 8.66; found C 74.95, H 8.60. t-Butyl-(3-cyclohexylprop-1-en-1-yl)phenylphosphine-borane (3ad). Yield 47% from 0.043 g (0.2 mmol) of 1a, purified with hexane/EtOAc (10/1), colorless oil. 1H NMR (CDCl3, 300 MHz): • 0.08-1.24 (bm, BH3, 3H), 1.02 (d JP-H 14.1 Hz, t-Bu, 9H), 1.09-1.20 (bm, 4H), 1.30-1.44 (bm, 1H), 1.50-1.70 (bm, 6H), 2.10-2.17 (m, 2H), 6.06-6.17 (m, 1H), 6.67-6.86 (m, 1H), 7.30-7.45 (m, 3H), 7.60-7.71 (m, 2H). 13C NMR (CDCl3, 75 MHz): • 25.36 (d, JP-C 2.9 Hz), 26.12, 26.30, 29.33 (d, JP-C 35.1 Hz), 30.85, 33.02, 33.11, 37.22 (d, JP-C 1.2 Hz), 43.43 (d, JP-C 14.4 Hz), 114.50 (d, JP-C 54.9 Hz), 128.07 (d, JP-C 9.5 Hz), 128.44 (d, JP-C 55.2 Hz), 130.70 (d, JP-C 2.6 Hz), 133.00 (d, JP-C 8.1 Hz), 154.08 (d, JP-C 9.5 Hz). 31P NMR (CDCl3, 121.5 MHz): • 24.85 (m). Elem. anal. for C18H30BP: calc. C 75.01, H 10.49; found C 74.75, H 10.22. (3-Cyclohexylpropen-3-yl)diphenylphosphine-borane (2bd). Yield 22% from 0.076 g (0.32 mmol) of 1b, purified with hexane/EtOAc (6/1), colorless oil. 1H NMR (CDCl3, 300 MHz): • 0.36-1.65 (bm, BH3, 3H), 1.31-1.49 (m, 3H), 1.50-1.71 (m, 8H), 2.89-3.04 (m, 1H), 4.71-5.00 (m, 2H), 5.64-5.83 (m, 1H), 7.24-7.47 (m, 6H), 7.5-7.80 (m, 4H). 13C NMR (CDCl3, 75 MHz): •
Page 117 25.92, 26.45, 30.64 (d, JP-C 2.9 Hz), 33.59 (d, JP-C 9.5 Hz), 37.19, 47.43 (d, JP-C 31.9 Hz), 120.03 (d, JP-C 11.8 Hz), 128.19 (d, JP-C 9.8 Hz), 128.66 (d, JP-C 9.8 Hz), 129.35 (d, JP-C 58.3 Hz), 129.39 (d, JP-C 52.9 Hz), 130.24 (d, JP-C 2.6 Hz), 130.98 (d, JP-C 2.6 Hz), 132.15 (d, JP-C 2.9 Hz), 132.40 (d, JP-C 7.8 Hz), 133.07 (d, JP-C 8.1 Hz). 31P NMR (CDCl3, 121.5 MHz): • 19.36 (m). Elem. anal. for C21H28BP (as a mixture with 9d): calc. C 78.27, H 8.76; found C 78.45, H 8.70. (3-Cyclohexylpropen-1-yl)diphenylphosphine-borane (3bd). Yield 47% from 0.076 g (0.32 mmol) of 1b, purified with hexane/EtOAc (6/1), colorless oil. 1H NMR (CDCl3, 300 MHz): • 0.36-1.65 (bm, BH3, 3H), 1.31-1.49 (m, 3H), 1.50-1.71 (m, 8H), 2.08-2.18 (m, 2H), 5.97-6.13 (m, 1H), 6.47-6.68 (m, 1H), 7.24-7.47 (m, 6H), 7.49-7.62 (m, 4H). 13C NMR (CDCl3, 75 MHz): • 26.12, 26.29, 33.07, 38.24 (d, JP-C 2.9 Hz), 43.00 (d, JP-C 15.2 Hz), 119.05 (d, JP-C 58.3 Hz), 128.7 (d, JP-C 9.77 Hz), 130.24 (d, JP-C 63.2 Hz), 130.90 (d, JP-C 2.3 Hz), 132.29 (d, JP-C 9.2 Hz), 152.33 (d, JP-C 7.5 Hz). 31P NMR (CDCl3, 121.5 MHz): • 13.13 (m). Elem. anal. for C21H28BP (as a mixture with 8d): calc. C 78.27, H 8.76; found C 78.45, H 8.70. t-Butylphenyl-(3-trimethylsilylprop-1-en-1-yl)phosphine-borane (3ae). Yield 91% from 0.049 g (0.22 mmol) of 1a, purified with hexane/EtOAc (6/1), white solid. 1H NMR (CDCl3, 300 MHz): • 0.05 (s, 9H, TMS), 0.57-1.30 (bm, BH3, 3H), 1.09 (d, JP-H 13.7 Hz, t-Bu, 9H), 1.84-1.89 (m, 2H), 5.95-6.05 (m, 1H), 6.80-6.99 (m, 1H), 7.36-7.47 (m, 3H), 7.68-7.77 (m, 2H). 13C NMR (CDCl3, 75 MHz): • -1.83, 25.35 (d, JP-C 2.9 Hz), 28.00 (d, JP-C 14.1 Hz), 29.32 (d, JP-C 36.2 Hz), 110.24 (d, JP-C 58.3 Hz), 127.98 (d, JP-C 8.9 Hz), 128.94 (d, JP-C 52.3 Hz), 130.55 (d, JP-C 2.9 Hz), 132.95 (d, JP-C 8.3 Hz), 153.11 (d, JP-C 10.1 Hz). 31P NMR (CDCl3, 121.5 MHz): • 24.90 (m). Elem. anal. for C16H30BPSi: calc. C 65.75, H 10.35; found C 66.02, H 10.20. 3-(t-Butylphenylboranatophosphinyl)-pent-4-enoic acid ethyl ester (2af). Yield 23% from 0.101 g (0.46 mmol) of 1a, 3:1 inseparable mixture of diastereoisomers, purified with hexane/EtOAc (6/1), colorless oil. Major: 1H NMR (CDCl3, 300 MHz): • 0.15-1.56 (bm, BH3, 3H), 1.15 (d, JP-H 13.9 Hz, t-Bu, 9H), 1.28 (t, JH-H 7.0 Hz, 3H), 2.34 (ddd, JH-H 9.8 Hz, JH-H 12.0 Hz, JP-H 2.5 Hz, 2H), 3.71-3.87 (m, 1H), 3.99-4.12 (m, 3H), 5.23-5.30 (m, 1H), 5.35-5.44 (m, 1H), 5.99-6.15 (m, 1H), 7.43-7.53 (m, 3H), 7.75-7.83 (m, 2H). 31P NMR (CDCl3, 121.5 MHz): 37.20 (m). Minor: 1H NMR (CDCl3, 300 MHz): • 0.15-1.56 (bm, BH3, 3H), 1.04 (d, JP-H 14.0 Hz, t-Bu, 9H), 1.10 (t, JH-H 6.9 Hz, 3H), 2.15-2.28 (m, 1H), 2.42-2.57 (m, 1H), 3.14-3.29 (m, 1H), 4.15- 4.33 (m, 2H), 5.05-5.22 (m, 2H), 5.88-6.06 (m, 1H), 7.39-7.50 (m, 3H), 7.64-7.74 (m, 2H). 31P NMR (CDCl3, 121.5 MHz): • 36.87 (m). Elem. anal. for C17H28BO2P: calc. C 66.69, H 9.22; found C 66.40, H 9.35. 3-(t-Butylphenylboranatophosphinyl)pent-3-enoic acid ethyl ester (3af). Yield 20% from 0.041 g (0.19 mmol) of 1a, colorless oil. 1H NMR (CDCl3, 300 MHz): • 0.24-1.32 (bm, BH3, 3H), 1.08 (d, JP-H 14.0 Hz, t-Bu, 9H), 1.23 (t, JH-H 7.2 Hz, 3H), 2.46-2.54 (m, 2H), 2.58-2.68 (m, 2H), 4.12 (q, JH-H 7.2 Hz, 2H), 6.25-6.35 (m, 1H), 6.75-6.92 (m, 1H), 7.39-7.49 (m, 3H), 7.67- 7.76 (m, 2H). 13C NMR (CDCl3, 75 MHz): • .14.17, 25.35 (d, JP-C 2.6 Hz), 29.68, 32.64 (d, JP-C 1.2 Hz), 60.62, 115.39 (d, JP-C 54.3 Hz), 128.20 (d, JP-C 9.8 Hz), 130.89 (d, JP-C 2.0 Hz), 133.08
Page 118 (d, JP-C 8.1 Hz), 152.24 (d, JP-C 11.5 Hz), 172.36. 31P NMR (CDCl3, 121.5 MHz): • 25.30 (m). Elem. anal. for C17H28BO2P: calc. C 66.69, H 9.22; found C 66.74, H 9.10. 1,6-Bis(t-butylphenylboranatophosphinyl)-hexa-1,5-diene (5). Mixture of two diastereoisomers dr 50:50, yield 66% from 0.110g (0.50 mmol) of 1a, purified with hexane/EtOAc (6/1), pasty white solid. 1H NMR (CDCl3, 300 MHz): • 0.13-1.34 (bm, BH3, 3H), 1.02 (d, JP-H 14.1 Hz, t-Bu, 9H), 1.08 (d, JH-H 14.0 Hz, 9H), 2.50-2.55 (m, 4H), 6.24-6.34 (m, 2H), 6.75-6.93 (m, 2H), 7.39-7.50 (m, 6H), 7.66-7.76 (m, 4H). 31P NMR (CDCl3, 121.5 MHz): • 25.39 (m). Elem. anal. for C26H42B2OP2: calc. C 71.27, H 9.66; found C 71.45, H 9.32. General procedure for reaction between allylphosphine-borane 1 and carbonyl compounds In a Schlenk flask equipped with magnetic stirrer and argon inlet was placed allylphosphine- borane 1 (0.040-0.193g, 0.18-0.88 mmol) in 10 mL of dry THF. Then, reaction was cooled to -78 oC and 1.6 M BuLi solution in hexanes (0.17-0.83 mL, 0.27-1.32 mmol) was added and the resulting mixture was stirred at -78 oC for 0.5h. Then, the bath was taken out and electrophile (0.36-1.76 mmol) was added. The mixture was stirred for overnight then was quenched with saturated NH4Cl solution and formed mixture was extracted with DCM (3x15 mL). Combined organic phases were dried over anhydrous magnesium sulfate, filtered and evaporated to dryness. The residue was purified by flash chromatography using hexane/EtOAc 2:1 to 50:1 as eluent to give product. t-Butyl-(4-hydroxy-4-phenyl-but-1-en-1-yl)phenylphosphine-borane (8ag). Mixture of two diastereoisomers, dr 61:39, yield 97% from 0.193 g (0.88 mmol) of 1a, purified with hexane/EtOAc (6/1), yellow oil. Major: 1H NMR (CDCl3, 300 MHz): • 0.11-1.26 (bm, BH3, 3H), 0.99 (d, JP-H 14.0 Hz, t-Bu, 9H), 2.64-2.84 (m, 2H), 2.85 (bs, OH, 1H), 4.79-4.86 (m, 1H), 6.17-6.28 (m, 1H), 6.71-6.90 (m, 1H), 7.29-7.36 (m, 5H), 7.36-7.49 (m, 3H), 7.56-7.70 (m, 2H). 13C NMR (CDCl3, 75 MHz): • 25.24 (d, JP-C 2.9 Hz), 29.32 (d, JP-C 35.1 Hz), 44.86 (d, JP-C 14.1 Hz), 72.90 (d, JP-C 1.2 Hz), 117.50 (d, JP-C 54.0 Hz), 125.83, 127.69, 128.10 (d, JP-C 9.5 Hz), 128.48, 130.77 (d, JP-C 2.6 Hz), 133.02 (d, JP-C 7.8 Hz), 143.34, 149.95 (d, JP-C 9.5 Hz). 31P NMR (CDCl3, 121.5 MHz): • 25.59 (bm). Minor: 1H NMR (CDCl3, 300 MHz): • 0.11-1.26 (bm, BH3, 3H), 1.04 (d, JP-H 14.2 Hz, t-Bu, 9H), 2.64-2.84 (m, 2H), 2.85 (bs, OH, 1H), 4.79-4.86 (m, 1H), 6.17-6.28 (m, 1H), 6.71-6.90 (m, 1H), 7.29-7.36 (m, 5H), 7.36-7.49 (m, 3H), 7.56-7.70 (m, 2H). 13C NMR (CDCl3, 75 MHz): • 25.30 (d, JP-C 2.9 Hz), 29.35 (d, JP-C 35.1 Hz), 44.83 (d, JP-C 14.1 Hz), 72.85 (d, JP-C 1.2 Hz), 117.46 (d, JP-C 54.3 Hz), 125.74, 127.64, 128.08 (d, JP-C 9.5 Hz), 128.46, 130.73 (d, JP-C 3.2 Hz), 133.00 (d, JP-C 8.1 Hz), 143.41, 150.03 (d, JP-C 8.9 Hz). 31P NMR (CDCl3, 121.5 MHz): • 25.59 (bm). Elem. anal. for C20H28BOP: calc. C 73.64, H 8.65; found C 73.78, H 8.80. (4-Hydroxy-4-phenyl-but-1-en-1-yl)diphenylphosphine-borane (8bg). Yield 77% from 0.049 g (0.20 mmol) of 1b, purified with hexane/EtOAc (2:1), yellow oil. 1H NMR (CDCl3, 300 MHz): • 0.31-1.49 (bm, BH3, 3H), 2.08 (bs, OH, 1H), 2.53-2.76 (m, 2H), 4.70-4.79 (m, 1H), 5.94-6.10 (m, 1H), 6.36-6.57 (m, 1H), 7.14-7.49 (m, 15H). 13C NMR (CDCl3, 75 MHz): • 44.40 (d, JP-C 15.2 Hz), 72.93 (d, JP-C 1.2 Hz), 121.85 (d, JP-C 57.5 Hz), 125.80, 127.75, 128.54, 128.63 (d, JP-C
Page 119 10.1 Hz), 128.66 (d, JP-C 10.4 Hz), 129.59 (d, JP-C 58.9 Hz), 129.64 (d, JP-C 59.2 Hz), 130.94 (d, JP-C 2.6 Hz), 130.99 (d, JP-C 2.3 Hz), 132.31 (d, JP-C 9.5 Hz), 132.37 (d, JP-C 9.8 Hz), 143.25, 148.15 (d, JP-C 7.5 Hz). 31P NMR (CDCl3, 121.5 MHz): • 13.55 (m). Elem. anal. for C22H24BOP: calc. C 76.32, H 6.99; found C 76.50, H 7.04. 5-(1-Hydroxy-1-phenylmethyl)-2-phospholene-borane (12cg). Yield 41% from 0.049 g (0.28 mmol) of 1c, purified with hexane/EtOAc (6:1) mixture of two diastereoisomers, dr 59:41, as a mixture with benzyl alcohol (29%). 1H-NMR (CDCl3, 300 MHz): • 0.14-1.30 (bm, BH3, 3H), 2.14-2.41 (m, 3H), 3.36-3.48 (bs, OH, 1H), 4.39-4.65 (m, 1H), 5.96-6.11 (m, 1H), 6.02-6.20 (m, 1H), 6.27-6.45 (m, 1H), 6.95-7.11 (m, 1H), 7.19-7.44 (m, 8H), 7.48-7.60 (m, 2H). 31P NMR (CDCl3, 121.5 MHz): • 26.58 and 28.89 (m). t-Butyl-(4-hydroxy-4-(p-tolyl)-but-1-en-1-yl)phenylphosphine-borane (8ah). Mixture of two diastereoisomers, dr 50:50, yield 64% from 0.042 g (0.19 mmol) of 1a, purified with hexane/EtOAc (6/1), colorless oil. 1H NMR (CDCl3, 300 MHz): • 0.07-1.18 (bm, BH3, 3H), 0.92 (d, JP-H 14.0 Hz, t-Bu, 9H) and 0.97 (d, JP-H =14.2 Hz, t-Bu, 9H), 2.03 (bs, OH, 1H), 2.23 (s, 3H), 2.54-2.73 (m, 2H), 4.95-5.03 (m, 1H), 6.09-6.22 (m, 1H), 6.66-6.86 (m, 1H), 6.95-7.18 (m, 4H), 7.27-7.42 (m, 3H), 7.56-7.64 (m, 2H) and 7.48-7.56 (m, 2H). 13C NMR (CDCl3, 75 MHz): • 21.55 and 21.57, 25.75 (d, JP-C 2.9 Hz) and 2.83 (d, JP-C 2.6 Hz), 29.85 (d, JP-C 35.1 Hz) and 29.9 (d, JP-C 35.1 Hz), 45.30 (d, JP-C 14.1 Hz), 73.26 (d, JP-C 1.2 Hz) and 73.29 (d, JP-C 1.2 Hz), 117.86 (d, JP-C 54.0 Hz) and 117.90 (d, JP-C 54.3 Hz), 126.22 and 126.31, 128.54 (d, JP-C 52.3 Hz) and 128.60 (d, JP-C 52.3 Hz), 128.57 (d, JP-C 8.9 Hz) and 128.62 (d, JP-C 9.3 Hz), 129.64 and 129.65, 131.24 (d, JP-C 2.3 Hz) and 131.30 (d, JP-C 2.6 Hz), 133.54 (d, JP-C 7.8 Hz) and 133.55 (d, JP-C 7.8 Hz), 137.73 and 138.36, 150.61 (d, JP-C 9.2 Hz) and 150.70 (d, JP-C 9.2 Hz). 31P NMR (CDCl3, 121.5 MHz): • 25.43 (m). Elem. anal. for C21H30BOP: calc. C 74.13, H 8.89; found C 74.00, H 8.70. (4-Hydroxy-4-(p-tolil)-but-1-en-1-yl)diphenylphosphine-borane (8bh). Yield 65% from 0.066 g (0.28 mmol) of 1b, purified with hexane/EtOAc (6:1), yellow oil. 1H NMR (CDCl3, 300 MHz): • 0.24-1.63 (m, BH3, 3H), 1.90 (bs, OH, 1H), 2.26 (s, 3H), 2.48-2.75 (m, 2H), 4.69-4.76 (m, 1H), 5.95-6.08 (m, 1H), 6.38-6.58 (m, 1H), 7.01-7.18 (m, 4H), 7.23-7.50 (m, 10H). 13C NMR (CDCl3, 75 MHz): • 21.10, 44.34 (d, JP-C 14.9 Hz), 72.78 (d, JP-C 0.9 Hz), 121.58 (d, JP-C 57.2 Hz), 125.75, 128.59 (d, JP-C 10.4 Hz), 128.63 (d, JP-C 10.1 Hz), 129.17, 129.63 (d, JP-C 58.9 Hz), 129.70 (d, JP-C 58.9 Hz), 130.90 (d, JP-C 2.6 Hz), 130.97 (d JP-C 2.9 Hz), 132.31 (d, JP-C 9.5 Hz), 132.37 (d, JP-C 9.5 Hz), 147.40, 140.26, 148.33 (d, JP-C 7.5 Hz. 31P NMR (CDCl3, 121.5 MHz): • 13.56 (m). Elem. anal. for C23H26BOP: calc. C 76.68, H 7.27; found C 76.84, H 7.20. t-Butyl-(4-hydroxy-4-(o-tolyl)-but-1-en-1-yl)phenylphosphine-borane (8ai). Mixture of two diastereoisomers, dr 53:47, yield 67% from 0.065 g (0.29 mmol) of 1a, purified with hexane/EtOAc (6/1), pale yellow oil. Major: 1H NMR (CDCl3, 300 MHz): • 0.06-1.11 (bm, BH3, 3H), 0.92 (d, JP-H 14.2 Hz, t-Bu, 9H), 1.86 (bs, OH, 1H), 2.23 (s, 3H), 2.58-2.68 (m, 2H), 4.96-5.02 (m, 1H), 6.10-6.22 (m, 1H), 6.67-6.86 (m, 1H), 6.95-7.18 (m, 4H), 7.27-7.42 (m, 3H), 7.56-7.64 (m, 2H). 13C NMR (CDCl3, 75 MHz): • 19.08, 25.24 (d, JP-C 2.6 Hz), 29.31 (d, JP-C 35.4 Hz), 44.00 (d, JP-C 14.4 Hz), 68.97
Page 120 (d, JP-C 1.4 Hz), 117.52 (d, JP-C 54.0 Hz), 125.23, 127.40, 128.08 (d, JP-C 52.0 Hz), 128.12 (d, JP-C 9.5 Hz), 128.14, 130.43, 130.78 (d, JP-C 2.6 Hz), 133.00 (d, JP-C 7.8 Hz), 134.33, 141.33, 150.06 (d, JP-C 9.5 Hz). 31P NMR (CDCl3, 121.5 MHz): • 25.44 (m). Minor: 1H NMR (CDCl3, 300 MHz): • 0.06-1.11 (bm, BH3, 3H), 0.98 (d, JP-H 14.1 Hz, t-Bu, 9H), 1.86 (bs, OH, 1H), 2.17 (s, 3H), 2.58-2.68 (m, 2H), 4.96-5.02 (m, 1H), 6.10-6.22 (m, 1H), 6.67- 6.86 (m, 1H), 6.95-7.18 (m, 4H), 7.27-7.42 (m, 3H), 7.48-7.56 (m, 2H). 13C NMR (CDCl3, 75 MHz): • 19.01, 25.32 (d, JP-C 2.9 Hz), 29.37 (d, JP-C 35.1 Hz), 43.96 (d, JP-C 14.1 Hz), 68.97 (d, JP-C 1.4 Hz), 117.36 (d, JP-C 54.0 Hz), 125.17, 127.35, 128.00 (d, JP-C 52.3 Hz), 128.22 (d, JP-C 9.5 Hz), 128.94, 130.41, 130.73 (d, JP-C 2.6 Hz), 132.96 (d, JP-C 8.1 Hz), 134.29, 141.45, 150.15 (d, JP-C 9.2 Hz). 31P NMR (CDCl3, 121.5 MHz): • 25.44 (m). Elem. anal. for C21H30BOP: calc. C 74.13, H 8.89; found C 74.38, H 8.99. (4-Hydroxy-4-(o-tolil)-but-1-en-1-yl)diphenylphosphine-borane (8bi). Yield 68% from 0.066 g (0.27 mmol) of 1b, purified with hexane/EtOAc (6:1), yellow oil. 1H NMR (CDCl3, 300 MHz): • 0.32-1.61 (bm, BH3, 3H), 1.75 (bs, 1H, OH), 2.22 (s, 3H), 2.57-2.73 (m, 2H), 4.99-5.08 (m, 1H), 5.98-6.16 (m, 1H), 6.43-6.62 (m, 1H), 7.00-7.20 (m, 4H), 7.24-7.52 (bm, 10H). 13C NMR (CDCl3, 75 MHz): • 19.12, 43.49 (d, JP-C 15.2 Hz), 69.12 (d, JP-C 1.2 Hz), 121.87 (d, JP-C 57.2 Hz), 125.29, 126.42, 127.48, 128.67 (d, JP-C 10.4 Hz), 128.70 (d, JP-C 10.1 Hz), 129.68 (d, JP-C 59.2 Hz), 129.70 (d, JP-C 58.9 Hz), 130.48, 130.96 (d, JP-C 2.6 Hz), 131.01 (d, JP-C 2.3 Hz), 132.33 (d, JP-C 9.5 Hz), 132.39 (d, JP-C 9.5 Hz), 134.36, 141.34, 148.25 (d, JP-C 7.5 Hz). 31P NMR (CDCl3, 121.5 MHz): • 13.37 (m). Elem. anal. for C23H26BOP: calc. C 76.68, H 7.27; found C 76.70, H 7.25. t-Butyl-(4-hydroxy-4-methylpent-1-en-1-yl)phenylphosphine-borane (8aj). Yield 99% from 0.045 g (0.2 mmol) of 1a, purified with hexane/EtOAc (1/1), pale yellow oil. 1H NMR (CDCl3, 300 MHz): • 0.11-1.20 (bm, BH3, 3H), 1.30 (d, JP-H 14.2 Hz, t-Bu, 9H), 1.18 (s, 6H), 1.77 (bs, OH, 1H), 2.39-2.44 (m, 2H), 6.20-6.30 (m, 1H), 6.73-6.90 (m, 1H), 7.31-7.41 (m, 3H), 7.62-7.70 (m, 2H). 13C NMR (CDCl3, 75 MHz): • 25.30 (d, JP-C 2.6 Hz), 29.16, 29.25, 29.35 (d, JP-C 35.1 Hz), 49.52 (d, JP-C 14.4 Hz), 70.57 (d, JP-C 1.2 Hz), 117.68 (d, JP-C 54.0 Hz). 128.06 (d, JP-C 52.3 Hz), 128.11 (d, JP-C 9.5 Hz), 130.80 (d, JP-C 2.6 Hz), 132.98 (d, JP-C 8.1 Hz), 150.51 (d, JP-C 8.9 Hz). 31P NMR (CDCl3, 121.5 MHz): • 25.43 (m). Elem. anal. for C16H28BOP: calc. C 69.08, H 10.15; found C 69.00, H 9.99. (4-Hydroxy-4-methylpent-1-en-1-yl)diphenylphosphine-borane (8bj). Yield 73% from 0.046 g (0.19 mmol) of 1b, purified with hexane/EtOAc (6:1), yellow oil. 1H NMR (CDCl3, 300 MHz): • 0.33-1.62 (bm, BH3, 3H), 1.16 (s, 6H), 1.82 (bs, OH, 1H), 2.35-2.41 (m, 2H), 6.09-6.21 (m, 1H), 6.50-6.69 (m, 1H), 7.29-7.43 (m, 6H), 7.50-7.59 (m, 4H). 13C NMR (CDCl3, 75 MHz): • 29.34, 49.11 (d, JP-C 14.1 Hz), 70.66 (d, JP-C 1.2 Hz), 122.18 (d, JP-C 57.2 Hz), 128.73 (d, JP-C 10.4 Hz), 129.82 (d, JP-C 58.9 Hz), 131.04 (d, JP-C 2.6 Hz), 132.43 (d, JP-C 9.5 Hz), 148.70 (d, JP-C 7.5 Hz). 31P NMR (CDCl3, 121.5 MHz): • 13.36 (m). Elem. anal. for C18H24BOP: calc. C 72.51, H 8.11; found C 72.74, H 7.99. t-Butyl-(4-cyclohexylidene-4-hydroxy-but-1-en-1-yl)phenylphosphine-borane (8ak). Yield 71% from 0.047 g (0.21 mmol) of 1a, purified with hexane/EtOAc (6/1), colorless oil. 1H NMR
Page 121 (CDCl3, 300 MHz): • 0.08-1.29 (bm, BH3, 3H), 1.02 (d, JP-H 14.1 Hz, t-Bu, 9H), 1.30-1.59 (m, 10H), 2.37-2.43 (m, 2H), 6.19-6.30 (m, 1H), 6.75-6.92 (m, 1H), 7.31-7.44 (m, 3H), 7.62-7.70 (m, 2H). 13C NMR (CDCl3, 75 MHz): • 21.99, 22.01, 25.37 (d, JP-C 2.9 Hz), 25.51, 29.40 (d, JP-C 35.1 Hz), 37.41, 37.50, 48.35 (d, JP-C 13.8 Hz), 71.44 (d, JP-C 0.9 Hz), 117.81 (d, JP-C 53.7 Hz), 128.16 (d, JP-C 9.2 Hz), 128.19 (d, JP-C 51.7 Hz), 130.83 (d, JP-C 2.6 Hz), 133.04 (d, JP-C 7.8 Hz), 150.21 (d, JP-C 9.5 Hz). 31P NMR (CDCl3, 121.5 MHz): • 25.32 (m). Elem. anal. for C19H32BOP: calc. C 71.71, H 10.14; found C 71.79, H 9.97. (4-Cyclohexylidene-4-hydroxy-but-1-en-1-yl)diphenylphosphine-borane (8bk). Yield 53% from 0.038 g (0.16 mmol) of 1b, purified with hexane/EtOAc (6:1), colorless oil. 1H NMR (CDCl3, 300 MHz): • 0.30-1.48 (bm, BH3, 3H), 1.27-1.58 (m, 10H), 2.34-2.41 (m, 2H), 6.08- 6.21 (m, 1H), 6.54-6.73 (m, 1H), 7.30-7.44 (m, 6H), 7.49-7.60 (m, 4H). 13C NMR (CDCl3, 75 MHz): • 22.02, 25.50, 37.52, 47.99 (d, JP-C 15.5 Hz), 71.45, 122.09 (d, JP-C 56.9 Hz), 128.74 (d, JP-C 10.1 Hz), 131.01 (d, JP-C 2.6 Hz), 132.34 (d, JP-C 9.5 Hz), 148.50 (d, JP-C 7.8 Hz). 31P NMR (CDCl3, 121.5 MHz): • 13.29 (m). Elem. anal. for C21H28BOP: calc. C 74.57, H 8.34; found C 74.59, H 8.40. 5-(1'-Hydroxycyclohexyl)-3-phospholene-borane (11ck). Yield 31% from 0.050 g (0.28 mmol) of 1c, purified with hexane/EtOAc (6:1), colorless oil. 1H NMR (CDCl3, 300 MHz): • 0.39-1.76 (bm, BH3, 3H), 1.13-1.68 (m, 10H), 1.77-1.89 (m, 2H), 2.68 (bs, OH, 1H), 3.08-3.18 (m, 1H), 5.89-6.12 (m, 2H), 7.31-7.48 (m, 3H), 7.61-7.74 (m, 2H). 13C NMR (CDCl3, 75 MHz): • 21.44, 21.71, 25.43, 32.56 (d, JP-C 38.2 Hz), 35.16 (d, JP-C 4.6 Hz), 37.39 (d, JP-C 5.5 Hz), 74.19 (d, JP-C 2.6 Hz), 128.29 (d, JP-C 9.5 Hz), 129.76, 130.41 (d, JP-C 47.1 Hz), 131.06 (d, JP-C 9.2 Hz), 131.32 (d, JP-C 11.5 Hz), 131.41 (d, JP-C 2.3 Hz). 31P NMR (CDCl3, 121.5 MHz): • 25.38 (m). Elem. anal. for C16H24BOP: calc. C 70.10, H 8.82; found C 70.35, H 8.90. t-Butyl-(4-hydroxy-4-phenylpent-1-en-1-yl)phenylphosphine-borane (8al). Mixture of two diastereoisomers, dr 56:44, yield 36% from 0.084 g (0.38 mmol) of 1a, purified with hexane/EtOAc (6/1), colorless oil. Major: 1H NMR (CDCl3, 300 MHz): • 0.05-1.23 (bm, BH3, 3H), 0.90 (d, JP-H 14.2 Hz, t-Bu, 9H), 1.53 (s, 3H), 1.93 (bs, OH, 1H), 2.68-2.75 (m, 2H), 6.03-6.13 (m, 1H), 6.56-6.74 (m, 1H), 7.11- 7.41 (m, 8H), 7.47-7.57 (m, 2H). 13C NMR (CDCl3, 75 MHz): • 25.28 (d, JP-C 3.2 Hz), 29.32 (d, JP-C 35.3 Hz), 29.80, 49.95 (d, JP-C 14.1 Hz), 74.26 (d, JP-C 1.1 Hz), 118.32 (d, JP-C 54.0 Hz), 124.65, 126.80, 127.95 (d, JP-C 52.0 Hz), 128.07 (d, JP-C 9.5 Hz), 128.23, 130.73 (d, JP-C 2.3 Hz), 133.00 (d, JP-C 7.8 Hz), 146.71, 149.42 (d, JP-C 8.9 Hz). 31P NMR (CDCl3, 121.5 MHz): • 25.74 (m). Minor: 1H NMR (CDCl3, 300 MHz): • 0.05-1.23 (bm, BH3, 3H), 0.94 (d, JP-H 14.0 Hz, t-Bu, 9H), 1.54 (s, 3H), 1.93 (bs, OH, 1H), 2.68-2.75 (m, 2H), 6.03-6.13 (m, 1H), 6.56-6.74 (m, 1H), 7.11- 7.41 (m, 8H), 7.47-7.57 (m, 2H). 13C NMR (CDCl3, 75 MHz): • 25.24 (d, JP-C 2.9 Hz), 29.28 (d, JP-C 35.1 Hz), 29.59, 49.98 (d, JP-C 14.1 Hz), 74.20 (d, JP-C 1.1 Hz), 118.41 (d, JP-C 54.0 Hz), 124.67, 126.85, 127.95 (d, JP-C 52.0 Hz), 128.07 (d, JP-C 9.5 Hz), 128.23, 130.73 (d, JP-C 2.3 Hz), 133.04 (d, JP-C 7.8 Hz), 146.76, 149.42 (d, JP-C 8.9 Hz). 31P NMR (CDCl3, 121.5 MHz): • 25.74 (m). Elem. anal. for C21H30BOP: calc. C 74.13, H 8.89; found C 74.01, H 8.70.
Page 122 t-Butyl-(4-hydroxy-4-phenylpent-2-en-1-yl)phenylphosphine-borane (9al). Mixture of two diastereoisomers, dr 62:38, yield 24% from 0.084 g (0.38 mmol) of 1a, purified with hexane/EtOAc (6/1), colorless oil. Major: 1H NMR (CDCl3, 300 MHz): • 0.07-1.24 (bm, BH3, 3H), 1.05 (d, JP-H 13.7 Hz, t-Bu, 9H), 1.40 (s, 3H), 1.69 (bs, OH, 1H), 2.64-2.76 (m, 1H), 2.82-2.96 (m, 1H), 5.52-5.83 (m, 2H), 7.01- 7.20 (m, 5H), 7.30-7.46 (m, 3H), 7.58-7.67 (m, 2H). 13C NMR (CDCl3, 75 MHz): • 23.64 (d, JP-C 32.5 Hz), 25.49 (d, JP-C 2.0 Hz), 29.20, 74.32 (d, JP-C 1.7 Hz), 119.49 (d, JP-C 54.0 Hz), 124.88, 126.63, 127.98, 128.19 (d, JP-C 9.8 Hz), 131.13 (d, JP-C 2.6 Hz), 133.78 (d, JP-C 8.1 Hz), 141.66 (d, JP-C 10.6 Hz). 31P NMR (CDCl3, 121.5 MHz): • 32.13 (m). Minor: 1H NMR (CDCl3, 300 MHz): • 0.07-1.24 (bm, BH3, 3H), 1.04 (d, JP-H 13.7 Hz, t-Bu, 9H), 1.44 (s, 3H), 1.69 (bs, OH, 1H), 2.64-2.76 (m, 1H), 2.82-2.96 (m, 1H), 5.52-5.83 (m, 2H), 7.01- 7.20 (m, 5H), 7.30-7.46 (m, 3H), 7.58-7.67 (m, 2H). 13C NMR (CDCl3, 75 MHz): • 23.56 (d, JP-C 33.1 Hz), 25.49 (d, JP-C 2.0 Hz), 29.20, 74.22 (d, JP-C 1.7 Hz), 119.14 (d, JP-C 4.6 Hz), 125.09, 126.82, 128.05, 128.19 (d, JP-C 9.8 Hz), 131.13 (d, JP-C 2.6 Hz), 133.73 (d, JP-C 8.1 Hz), 141.97 (d, JP-C 10.3 Hz). 31P NMR (CDCl3, 121.5 MHz): • 32.13 (m). Elem. anal. for C21H30BOP: calc. C 74.13, H 8.89; found C 74.01, H 8.70. Diphenyl-(4-hydroxy-4-phenylpent-1-en-1-yl)phosphine-borane (8bl). Yield 67% from 0.058 g (0.24 mmol of 1b, purified with hexane/EtOAc (6:1), colorless oil. 1H NMR (CDCl3, 300 MHz): • 0.24-1.43 (bm, BH3, 3H), 1.53 (s, 3H), 1.77 (bs, OH, 1H), 2.65-2.71 (m, 2H), 5.88-6.01 (m, 1H), 6.26-6.44 (m, 1H), 7.15-7.41 (m, Ph, 15H). 13C NMR (CDCl3, 75 MHz): • 29.88, 49.69 (d, JP-C 14.7 Hz), 74.32 (d, JP-C 0.9 Hz), 122.55 (d, JP-C 56.9 Hz), 124.71, 126.87, 128.30, 128.62 (d, JP-C 10.4 Hz), 128.64 (d, JP-C 10.1 Hz), 129.54 (d, JP-C 58.9 Hz), 130.93 (d, JP-C 2.6 Hz), 130.97 (d, JP-C 2.3 Hz), 132.35 (d, JP-C 9.5 Hz), 132.37 (d, JP-C 9.8 Hz), 146.61, 147.79 (d, JP-C 6.9 Hz). 31P NMR (CDCl3, 121.5 MHz): • 13.66 (m). Elem. anal. for C23H26BOP: calc. C 76.68, H 7.27; found C 76.50, H 7.10. 5-(1'-Hydroxy-1'-phenylethyl)-2-phospholene-borane (12cl). Yield 76% from 0.050 g (0.28 mmol) of 1c, purified with hexane/EtOAc (6:1), colorless oil. 1H NMR (CDCl3, 300 MHz): • 0.23-1.29 (bm, BH3, 3H), 1.63 (s, 3H), 2.01-2.08 (m, 2H), 3.56-3.64 (m, 1H), 6.06-6.22 (m, 1H), 6.75-6.92 (m, 1H), 7.24-7.44 (m, 8H), 7.50-7.61 (m, 2H). 13C NMR (CDCl3, 75 MHz): • 25.86 (d, JP-C 39.4 Hz), 27.69, 58.74, 75.46 (d, JP-C 5.2 Hz), 125.05, 125.25 (d, JP-C 49.1 Hz), 127.19, 128.34, 128.70 (d, JP-C 9.8 Hz), 130.01 (d, JP-C 46.8 Hz), 131.33 (d, JP-C 2.6 Hz), 131.55 (d, JP-C 9.8 Hz), 150.42 (d, JP-C 7.2 Hz). 31P NMR (CDCl3, 121.5 MHz): • 45.15 (m). Elem. anal. for C18H22BOP: calc. C 73.00, H 7.49; found C 73.11, H 7.54. t-Butyl-(4-hydroxy-4-methyl-hexa-1,5-dien-1-yl)phenylphosphine-borane (8am). Mixture of two diastereoisomers, dr 58:42, yield 84% from 0.074 g (0.33 mmol) of 1a, purified with hexane/EtOAc (6:1), colorless oil. Major: 1H NMR (CDCl3, 300 MHz): • 0.12-1.42 (bm, BH3, 3H), 1.07 (d, JP-H 14.1 Hz, t-Bu, 9H), 1.29 (s, 3H, Me), 2.50-2.54 (m, 2H), 5.05 (dd, JH-H 1.0 Hz, JH-H 10.7 Hz, 1H), 5.20 (dd, JH-H 1.0 Hz, JH-H 17.3 Hz, 1H), 5.91 (dd, JH-H 10.7 Hz, JH-H 17.3 Hz, 1H), 6.29-6.34 (m, 1H), 6.71-6.88 (m, 1H), 7.35-7.49 (m, 3H), 7.65-7.75 (m, 2H). 31P NMR (CDCl3, 121.5 MHz): • 25.44 (m).
Page 123 Minor: 1H NMR (CDCl3, 300 MHz): • 012-1.42 (bm, BH3, 3H), 1.07 (d, JP-H 14.1 Hz, t-Bu, 9H), 1.29 (s, 3H, Me), 2.50-2.54 (m, 2H), 5.04 (dd, JH-H 1.0 Hz, JH-H 10.8 Hz, 1H), 5.18 (dd, JH-H 1.0 Hz, JH-H 17.4 Hz, 1H), 5.90 (dd, JH-H 10.8 Hz, JH-H 17.4 Hz, 1H), 6.24-6.28 (m, 1H), 6.71-6.88 (m, 1H), 7.35-7.49 (m, 3H), 7.65-7.75 (m, 2H). 31P NMR (CDCl3, 121.5 MHz): • 25.92 (m). Elem. anal. for C17H28BOP: calc. C 70.36, H 9.73; found C 70.69, H 9.49. (4-Hydroxy-4-methyl-hexa-1,5-dien-1-yl)diphenylphosphine-borane (8bm) and (4-hydroxy- 4-methyl-hexa-1,5-dien-3-yl)diphenylphosphine-borane (10bm). Product ratio 45:55, yield 91% from 0.084 g (0.35 mmol) of 1b, purified with hexane/EtOAc (6/1), colorless oil. Compound 8bm. 1H NMR (CDCl3, 300 MHz): • 0.12-1.25 (bm, BH3, 3H), 1.23 (s, 3H), 2.46- 2.52 (m, 2H), 5.01 (dd, JH-H 1.4 Hz, JH-H 10.8 Hz, 1H), 5.18 (dd, JH-H 1.4 Hz, JH-H 17.3 Hz, 1H), 5.90 (dd, JH-H 1.4 Hz, JH-H 10.8 Hz, 1H), 6.12-6.29 (m, 1H), 6.55-6.71 (m, 1H), 7.34-7.51 (m, 6H), 7.55-7.71 (m, 4H). 31P NMR (CDCl3, 121.5 MHz): • 13.21 (m). Compound 12bm (mixture of diastereomers). 1H NMR (CDCl3, 300 MHz): • 0.12-1.25 (bm, BH3, 6H), 1.25 (s, 3H), 1.26 (s, 3H), 2.99-3.08 (m, 1H), 3.22-3.33 (m, 1H), 4.79-4.86 (m, 1H), 4.81-4.88 (m, 1H), 5.03-5.05 (m, 1H), 5.06-5.08 (m, 1H), 5.56-5.71 (m, 4H), 6.08-6.14 (m, 1H), 6.14-6.20 (m, 1H), 6.51-6.73 (m, 2H), 7.34-7.51 (m, 12H), 7.55-7.71 (m, 8H). 31P NMR (CDCl3, 121.5 MHz): • 21.39 and 21.81 (m). t-Butyl-(4-hydroxy-4-methyl-oct-1-en-1-yl)phenylphosphine-borane (8an). Yield 81% from 0.047 g (0.21 mmol) of 1a, purified with hexane/EtOAc (6/1), colorless oil. 1H NMR (CDCl3, 300 MHz): • 0.17-1.30 (bm, BH3, 3H), 0.89 (t, JH-H 6.95 Hz, 3H), 1.10 (d, JP-H 13.7 Hz, t-Bu, 9H), 1.19 (s, 3H), 1.27-1.35 (m, 4H), 1.42-1.49 (m, 2H), 1.53 (bs, 1H), 2.47 (bd, JH-H 7.31 Hz), 6.27-6.39 (m, 1H), 6.79-6.97 (m, 1H), 7.38-7.51 (m, 3H), 7.69-7.77 (m, 2H). 31P NMR (CDCl3, 121.5 MHz): 25.40 ppm (m). Elem. anal. for C19H34BOP: calc. C 71.26, H 10.70; found C 71.35, H 10.92. 4-(t-Butylphenylboranatophosphinyl)buten-3-oic acid (8ao). Yield 76% from 0.062 g (0.29 mmol) of 1a, purified with hexane/EtOAc (1/1), colorless oil. 1H NMR (CDCl3, 300 MHz): • 0.08-1.29 (bm, BH3, 3H), 1.03 (d, JP-H 14.4 Hz, t-Bu, 9H), 3.28-3.33 (m, 2H), 6.33-6.43 (m, 1H), 6.73-6.90 (m, 1H), 7.32-7.43 (m, 3H), 7.62-7.70 (m, 2H), 9.84 (bs, 1H). 13C NMR (CDCl3, 75 MHz): 25.37 (d, JP-C 2.9 Hz), 29.42 (d, JP-C 34.8 Hz), 47.72 (d, JP-C 14.4 Hz), 117.78 (d, JP-C 54.0 Hz), 128.18 (d, JP-C 9.5 Hz), 128.19 (d, JP-C 51.7 Hz), 130.86 (d, JP-C 2.6 Hz), 133.05 (d, JP-C 7.8 Hz), 150.42 (d, JP-C 8.62 Hz), 207.12. 31P NMR (CDCl3, 121.5 MHz): 26.40 ppm (m). Elem. anal. for C14H22BO2P: calc. C 63.67, H 8.40; found C 63.50, H 8.36. 4-(Diphenylboranatophosphinyl)buten-3-oic acid (8bo). Yield 92% from 0.125 g (0.52 mmol) of 1b, purified with EtOAc as eluent), white solid, m.p. 145-147 °C. 1H NMR (CDCl3, 300 MHz): • 0.25-1.58 (bm, BH3, 3H), 3.20-3.27 (m, 2H), 3.37 (bs, 1H), 6.17-6.30 (m, 1H), 6.48- 6.66 (m, 1H), 7.31-7.45 (m, 6H), 7.50-7.60 (m, 4H). 13C NMR (CDCl3, 75 MHz): • 39.49 (d, JP-C 15.8 Hz), 122.69 (d, JP-C 57.2 Hz), 128.70 (d, JP-C 10.1 Hz), 129.09 (d, JP-C 59.5 Hz), 131.13 (d, JP-C 2.3 Hz), 132.36 (d, JP-C 9.8 Hz), 143.53 (d, JP-C 8.3 Hz), 172.10. 31P NMR (CDCl3, 121.5 MHz): 13.84 (m). Elem. anal. for C16H18BO2P: calc. C 67.64, H 6.39; found C 67.70, H 6.50.
Page 124 2-(t-Butylphenylboranatophosphinyl)pent-2-eno-1,5-dicarboxylic acid dimethyl ester (13ar). Yield 40% from 0.051 g (0.23 mmol) of 1a, purified with hexane/EtOAc (6/1) as eluent, colorless oil. 1H NMR (CDCl3, 300 MHz): • 0.08-1.23 (bm, 3H, BH3), 1.06 (d, JP-H 14.4 Hz, t- Bu, 9H), 2.99-3.11 (m, 1H), 3.34-3.48 (m, 1H), 3.65 (s, 3H), 3.79 (s, 3H), 7.01-7.10 (m, 1H), 7.34-7.48 (m, 3H), 7.61-7.69 (m, 2H). 13C NMR (CDCl3, 75 MHz): • 25.28 (d, JP-C 2.6 Hz), 29.84 (d, JP-C 30.5 Hz), 30.91, 52.39, 52.47, 118.24 (d, JP-C 50.6 Hz), 128.41 (d, JP-C 9.5 Hz), 129.45 (d, JP-C 52.0 Hz), 131.62 (d, JP-C 2.9 Hz), 133.47 (d, JP-C 8.6 Hz), 150.27 (d, JP-C 8.9 Hz), 206.93, 210.14. 31P NMR (CDCl3, 121.5 MHz): • 34.60 ppm (m). Elem. anal. for C17H26BO4P: calc. C 60.74, H 7.80; found C 60.47, H 7.62. 2-(Diphenylboranatophosphinyl)pent-2-eno-1,5-dicarboxylic acid dimethyl ester (13br). Yield 86% from 0.106 g (0.44 mmol) of 1a, purified with hexane/EtOAc (6/1) as eluent, colorless oil. 1H NMR (CDCl3, 300 MHz): • 0.32-1.58 (bm, BH3, 3H), 3.36-3.45 (m, 2H), 3.63 (s, 3H), 3.67 (s, 3H), 6.07-7.06 (m, 1H), 7.34-7.48 (m, 6H), 7.56-7.64 (m, 4H). 13C NMR (CDCl3, 75 MHz): • 52.29, 52.51, 127.66 (d, JP-C 54.3 Hz), 128.93 (d, JP-C 10.1 Hz), 128.66 (d, JP-C 52.3 Hz Ph), 131.67 (d, JP-C 2.6 Hz), 132.28 (d, JP-C 9.2 Hz), 1541.30 (d, JP-C 2.9 Hz), 163.76 (d, JP-C 2.0 Hz), 134.76 (d, JP-C 2.3 Hz). 31P NMR (CDCl3, 121.5 MHz): 18.49 (m). Elem. anal. for C19H22BO4P: calc. C 64.07, H 6.23; found C 64.30, H 6.40. t-Butyl-1-(4-hydroxy-4-(p-nitrophenyl)but-1-en-1-yl)phenylphosphine-borane (8ap). Mixture of two diastereoisomers, yield 18% based on 1H NMR spectra of the isolated fraction from 0.040 g (0.18 mmol) of 1a, purified with hexane/EtOAc (6/1). 1H NMR (CDCl3, 300 MHz): • 0.22-1.16 (bm, BH3, 3H), 0.95 (d, JP-H 14.1 Hz, t-Bu, 9H) and 0.97 (d, JP-H 14.1 Hz, t- Bu, 9H), 2.23 (bs, OH, 1H), 2.55-2.78 (m, 2H), 4.83-5.02 (m, 1H), 6.07-6.24 (m, 1H), 6.62-6.86 (m, 1H), 7.26-7.49 (m, 5H), 7.96-8.06 (m, 2H), 8.08-8.15 (m, 2H). 31P NMR (CDCl3, 121.5 MHz): • 25.57 (bm). p-Nitrobenzyl alcohol (14p). Yield 26%, based on 1H NMR spectra of the isolated fraction. 1H NMR (CDCl3, 300 MHz): • 2.25 (bs, OH, 1H), 4,74 (s, 2H), 7.42-7.47 (m, 2H), 8.10-8.14 (m, 2H). t-Butyl-1-(4-hydroxy-4-(o-nitrophenyl)but-1-en-1-yl)phenylphosphine-borane (8aq). Mixture of two diastereoisomers, yield 36% based on 1H NMR spectra of the isolated fraction from 0.050 g (0.23 mmol) of 1a, purified with hexane/EtOAc (6/1). 1H NMR (CDCl3, 300 MHz): • 0.06-1.20 (bm, BH3, 3H), 0.97 (d, JP-H 14.1 Hz, t-Bu, 9H) and 1.00 (d, JP-H 13.8 Hz, t- Bu, 9H), 2.46 (bs, OH, 1H), 2.48-2.73 (m, 2H), 5.10-5.20 (m, 1H), 6.20-6.35 (m, 1H), 6.78-6.96 (m, 1H), 7.26-7.47 (m, 5H), 7.50-7.75 (m, 3H), 7.98-8.05 (m, 1H). 31P NMR (CDCl3, 121.5 MHz): • 25.57 (m). o-Nitrobenzyl alcohol (14q). Yield 29%, based on 1H NMR spectra of the isolated fraction. 1H NMR (CDCl3, 300 MHz): • 2.46 (bs, OH, 1H), 4.89 (s, 2H), 7.30-7.44 (m, 1H), 7.50-7.75 (m, 1H), 7.77-7.88 (m, 1H).
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