Divergent synthesis of 3-amino-3-deoxy- and 4-amino-4-deoxyhexoses

A new efficient synthesis of 3-amino-3-deoxy-D-altrose (13), 3-amino-3-deoxy-L-allose (17), and 4-amino-4-deoxy-D-talose (21) from 2,3-O-isopropylidene-D-glyceraldehyde (6) using N-(tert-butoxycarbonyl)-2-(tert-butyldimethylsiloxy)pyrrole (TBSOP) as homologative nucleophile is described. The procedure highlights the merits of densely functionalized homochiral heptonolactam 9 as a key divergent intermediate.