salts induce the kineticresolution of racemic α-substituted unsaturated carboxylicacids through asymmetric protolactonization. Both the lactones and the recovered carboxylicacids are obtained with high enantioselectivities and high S (= kfast/kslow) values. Asymmetric protolactonization also leads to the desymmetrization of achiral carboxylicacids. Notably, chiral phosphonous acid diester not only
手性phospho盐通过不对称的原内酯化诱导外消旋α-取代的不饱和羧酸的动力学拆分。内酯和回收的羧酸均具有高对映选择性和高S(= k fast / k slow)值。不对称的原内酯化也导致非手性羧酸的去对称化。值得注意的是,手性亚膦酸二酯不仅诱导了对映选择性,而且还促进了原内酰胺化。
Enantioselective alkylation of lactams and lactones via lithium enolate formation using a chiral tetradentate lithium amide in the presence of lithium bromide
作者:Jun-ichi Matsuo、Shu Kobayashi、Kenji Koga
DOI:10.1016/s0040-4039(98)02235-7
日期:1998.12
Enantioselectivealkylation of lactams and lactones can be realized up to 98% ee by deprotonation with a chiral tetradentate lithiumamide (4b) in the presence of lithiumbromide, and subsequent alkylation with active alkylating agents in non-chelating solvents.