Nucleophilic and free-radical additions of phosphines and phosphine chalcogenides to alkenes and alkynes

Issue in Honor of Prof. Edmunds Lukevics ARKIVOC 2006 (v) 12-36 3.2 Primary phosphines Similarly to phosphine, primary phosphines react with acetylenes according to the nucleophilic monoaddition mechanism to form Z-ethenylphosphines. With weakly electrophilic acetylenes, these reactions, as a rule, require strong bases to proceed. Phenylphosphine reacts with di(alkynyl)sulfides under the action of base system LiNH2- NH3 to afford 4-phenyl-4H-1,4-thiaphosphinines (Scheme 16).144 R R LiNH2 PhPH2 + S PhP S R NH3 liq R R = H, Alk Scheme 16 Primary alkyl- and arylalkylphosphines add to phenylacetylene in the KOH-DMSO suspension (60°C, 1-4 h) giving predominantly or exclusively Z,Z-isomers of bis(2phenylethenyl) organylphosphines (28) (Scheme 17) in good yield (up to 81%).159 KOH/DMSO Ph Ph RPH2 + Ph P (H2O) R 28 R = C6H13, PhCH2CH2, PhCH(Me)CH2 Scheme 17 Activated phenylcyanoacetylene reacts with alkylphosphines under milder conditions (KOH-dioxane suspension, 20-22oC) to afford, depending on the reactant ratio, either secondary 29 or tertiary 30 phosphines of Z-configuration in the yield of 70-91% (Scheme 18).160 According to ESR and UV data, the addition involves a single electron transfer.160 R R CN CN PhCN 2 PhCN RPH2 CN P P KOH/Dioxane KOH/Dioxane H R = Alk Ph Ph Ph 29 30 Scheme 18 ISSN 1424-6376 Page 24 ©ARKAT