A Simple Route to β,β-Trehalose via Trichloroacetimidates

Abstract
The reaction of 2,3,4,6-tetra-O-acetyl-β-D-glucopyranose with 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl trichloroacetimidate in CH2Cl2 promoted by BF3;OEt2 gives β,β-octaacetyltrehalose in up to 58% isolated yield, which is readily deacetylated to β,β-trehalose. The corresponding 2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyl penta-fluorophenylimidate is configurationally stable and inert to coupling under mild conditions.