Synthesis of α-C(1→3)-mannopyranoside of N-acetylgalactosamine, a new β-galactosidase inhibitor

Radical C-glycosidation of a 3-methylidene-7-oxabicyclo[2.2.1]heptan-2-one derivative with acetobromomannose gave a α-C-mannopyranoside that was converted into α-D-ManpCH2(1→3)-D-GalNAc, a C-disaccharide that inhibits β-galactosidase from jack bean with IC50 = 9.4 μM Ki = 7.5 μM (mixed mode of inhibition).