Stereoselective synthesis and crystal structure of 4,6-O-benzylidene-N-octyl-d-allosamine hydrochloride

The building block of N-alkyl derivative of allosamidin (chitinase inhibitor), 4,6-O-benzylidene-N-octyl-d-allosamine hydrochloride was stereoselectively synthesized in two steps under mild conditions. Nucleophilic addition of octylamine to 2-oxoglucopyranoside gave a ‘carbonyl group transfer’ product in 62% yield. Subsequent stereoselective reduction of newly formed CO with NaBH4 produced title compound in 75% yield. X-ray diffraction analysis indicates the title compound adopts syn 1, 2, 3 stereochemistry and chair–chair conformation. The crystal structure is stabilized by hydrogen bonds.