Enantioselective Organocatalyzed Consecutive Synthesis of Alkyl 4,5-Dihydrofuran-2-carboxylates from α-Keto Esters and (Z)-β-Chloro-β-nitrostyrenes

Abstract

Alkyl 4,5-dihydrofuran-2-carboxylates can be efficiently ob- tained via an enantioselective organocatalyzed consecutive reaction between _-keto esters and (Z)-(2-chloro-2-nitroethenyl)benzenes. The overall sequence combines a (R,R)-TUC-catalyzed Michael addition with a DABCO-promoted intramolecular O-alkylation leading to the title products as single diastereomers with enantiomeric excesses from 86% up to 97%.