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1CO2TIPSOHC1- TIPSCl, NaI, Et3N, MeCN4040OOTBSOTESMeTESOOMeOMeTBSOPPh3IHOTES+ OOTBSOTESMeTESOOMeOMeTBSOHOTESTIPSO2COOTBSOHMeTESOOMeOMeTBSOHOOOOHOHMeHOOMeOMeHOHOO41424344MeLi, LiBr1- TBAF, THF, 0oC2- 2,4,6-trichlorobenzoyl chloride, i-Pr2NEt3- DMAP, Toluene, 90oC (16h) HF, MeCN, -18oC2- O3, MeOH, CH2Cl23- Me2S Scheme 9 3.3 Alkylation of cyclododecanone Cyclododecanone 1 easily undergoes alkylation on its •-carbon under phase-transfer catalysis (PTC). •-Halopropionic aldehyde acetals 45a, b react readily with 1 to give the respective 2-(3- oxopropyl) cyclododecanone acetals 46a, b. Acid hydrolysis of acetals 46 resulted in formation of 12-hydroxybicyclo[9.3.1]pentadecan-15-one 48 probably formed due to intramolecular aldol condensation of ketoaldehyde 47.59 3-(2-Oxocyclododecyl)propionic acid and its esters are interesting starting materials for the synthesis of valuable aromatic substances such as decamethylene-8-valerolactone,60 pentadecanolide (exaltolide),61 and cyclopentadecanone (exaltone),62 as well as macrocyclic ketoimides and N-acetylketolactams.63 Accordingly, •-(2-
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