摘要:
Reaction of cyclic sulfites or carbonates of gamma,delta-dihydroxy (E)-alpha,beta-enoates with R2Cu(CN)Li2, BF3; RCu(CN)Li, BF3 (R = Me-,n-Bu-)afforded either diastereoselective S(N)2' products or reductive elimination product depending on reaction conditions. Addition of R2Cu(CN)Li2, BF3 (R = Me-, n-Bu-) to cyclic sulfite (1) or cyclic carbonate (3) (inverse addition) afforded highly regio-, (E)-stereo- and diastereoselectively alpha-alkylation products (6 and 8). By using this methodology, (2S, 5S)-trans-2-methyl-5-hexanolide, the pheromone of the carpenter bee Xylocopa hirutissima was synthesized.