AbstractA new enantioselective synthetic method for the synthesis of α,α‐dialkylmalonates with a quaternary carbon center was developed via α‐alkylation of prochiral malonates by phase‐transfer catalysis (PTC). Asymmetric α‐alkylation of benzylideneamino tert‐butyl α‐methylmalonates under phase‐transfer catalytic conditions in the presence of (S,S)‐3,4,5‐trifluorophenyl‐NAS bromide afforded the corresponding α,α‐dialkylmalonates in high yields (up to 97%) with excellent enantioselectivities (up to 98% ee). The products were then selectively hydrolyzed to chiral malonic monoacids under basic, acidic, or catalytic hydrogenation conditions.magnified image
Enantioselective phase-transfer catalytic α-alkylation of 2-methylbenzyl tert-butyl malonates
作者:Min Woo Ha、Suckchang Hong、Cheonhyoung Park、Yohan Park、Jihye Lee、Mi-hyun Kim、Jihoon Lee、Hyeung-geun Park
DOI:10.1039/c3ob40481a
日期:——
A new asymmetric synthetic method to prepare α,α-dialkylmalonates for the construction of a quaternary carbon center via phase-transfer catalytic (PTC) alkylation has been developed. Enantioselectiveα-alkylation of 2-methylbenzyl tert-butyl α-methylmalonates under phase-transfer catalytic conditions in the presence of (S,S)-3,4,5-trifluorophenyl-NAS bromide (10) afforded the corresponding α,α-dialkylmalonates