Grignard reagents or the Li[RCuI] reagents in ether favor the opposite syn-s-cis conformation. Influence of lithium ions on the stereoselective conjugate addition of the monoorganocuprate reagent, Li[BuCuI], has been investigated and two different mechanistic pathways are presented. The results show that iodotrimethylsilane (TMSI) is crucial for the asymmetric conjugate addition of the copper reagent, but
Conjugateadditions of MeCu, PhCu and BuCu to the chiral enoylimides 2 a-c in the presence of iodotrimethylsilane and lithium iodide in THF give the adducts, 4a-c in yields above 90 % and diastereoselectivities from 80 to 93%. The dominating diastereomers are different from those formed with LiR2Cu/TMSCl or in copper(I)-mediated addition of Grignard reagents. Corresponding additions to enoylamides
在THF中存在碘三甲基硅烷和碘化锂的情况下,将MeCu,PhCu和BuCu共轭添加到手性烯丙酰亚胺2 ac中,得到加合物4a-c,收率超过90%,非对映选择性为80%至93%。占主导地位的非对映异构体不同于由LiR 2 Cu / TMSCl形成的非对映异构体,或在铜(I)介导的格氏试剂中添加的非对映异构体。邻三苯甲基脯氨醇向烯酰胺中的相应添加也可产生高产率的共轭加合物,但非对映选择性较低,酰基部分的主要构型与酰亚胺相反。
Diastereoselective Thiophenol Addition to (S)-N-.alpha.,.beta.-Unsaturated carbonyl- .gamma.-[(trityloxy)methyl]-.gamma.-butyrolactams