Enantioselective formation of cis-3,5-dimethylcyclohexanone lithium enolate and stereoselective aldol reaction with benzaldehyde
作者:Marek Majewski、D. Mark Gleave
DOI:10.1021/jo00039a018
日期:1992.6
Deprotonation of cis-3,5-dimethylcyclohexanone (6) with chiral lithium amide bases 10-12 has been investigated. The resulting lithium enolates 7a,b react with benzaldehyde, acetic anhydride, or trimethylsilyl chloride to yield, respectively, the aldols 8 and 9, the acetates 13a,b, and the enol ethers 14a,b as nonracemic mixtures in high yields and up to 79% ee. Effects of solvents and additives on the selectivity of these reactions have been studied. A model based on the hypothesis that the deprotonation of 6 with lithium amides proceeds via a pericyclic transition state involving a dimer of the base is proposed.