Highly efficient asymmetric vinylogous Mannich reaction induced by O-pivaloylated d-galactosylamine as the chiral auxiliary

Abstract

The diastereospecific formation of β-N-glycoside-linked α-amino-2(5H)-furanone has been achieved with high yield via a vinylogous Mannich reaction. The reaction was performed by using O-pivaloylated galactosylamine 1 as a chiral template and ZnCl₂·Et₂O as a promoter in Et₂O. Imines 3 of aromatic compounds and trimethylsiloxyfuran 4 were converted to N-galactosyl α-amino-2(5H)-furanone 5, giving ratios of diastereomers higher than 20 : 1. This procedure provides rapid access to biologically important γ-butenolide derivatives.