Synthesis of alpha-C(1 -> 3)-mannopyranoside of N-acetylgalactosamine, a new beta-galactosidase inhibitor

Radical C-glycosidation of a 3-methylidene-7-oxabicyclo[2.2.1]heptan-2-one derivative with acetobromomannose gave a alpha-C-mannopyranoside that was converted into alpha-D-ManpCH(2)(1-->3)-D-GalNAc, a C-disaccharide that inhibits beta-galactosidase from jack bean with IC50 = 9.4 mu M and K-i = 7.5 mu M (mixed mode of inhibition). (C) 1999 Elsevier Science Ltd. All rights reserved.