Preparation of (2R)-2-acetoxy-D-forosamine for the total synthesis of spinosyns

A synthesis of 2-acetoxy-D-forosamine (4) starting from 1,2-O-propylidene-α-D-abequose (3,6- dideoxy-1,2-O-propylidene-α-D-xylo-hexopyranose) (5) was developed by introduction of an azide moiety at C-4 with inversion of configuration. The 2-acetoxy group in 4 allows a β-selective glycosidation of a secondary alcohol moiety which is necessary in the total synthesis of spinosyns.