Addition of organocopper reagents to cyclic sulfites or carbonates of γ,δ-dihydroxy (E)-α,β-enoates
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.
Stereoselective SN2′ alkylation reaction sequence of the γ,δ-epoxy α,β-unsaturated ester system via γ,δ-chlorohydrin intermediates by the use of a R3Al–CuCN reagent
A novel stereoselective SN2′ alkylation reaction sequence of the γ,δ-epoxy α,β-unsaturatedester system has been developed which involves a regioselective substitution reaction with chloride ions at the γ-position and a subsequent SN2′ alkylation reaction of the resulting γ-chloro-δ-hydroxy derivatives with a R3Al–CuCN reagent. The new methodology was demonstrated to be applicable to a variety of substrates
已经开发了γ,δ-环氧α,β-不饱和酯系统的新型立体选择性S N 2'烷基化反应序列,其涉及在γ-位与氯离子的区域选择性取代反应和随后的S N 2'烷基化反应R 3 Al–CuCN试剂合成的γ-氯代-δ-羟基衍生物。事实证明,该新方法可适用于多种底物,并提供各种δ-羟基-α-烷基-β,γ-不饱和酯,包括以高度立体选择性的方式在α-位带有季不对称碳原子的那些酯,以及高产。