Synthesis of methyl 3-O- and 2-O-carbamoyl-α-D-mannopyranosides and carbamoyl-group migration between them

Methyl 3-O- and 2-O-carbamoyl-α-D-mannopyranosides, (2 and 3), were synthesized from methyl α-D-mannopyranoside via ammonolysis of a cyclic carbonate or a p-nitrophenoxycarbonate, as shown in Charts 1 and 2. Carbamoyl-group migration between the C-2 and C-3 hydroxyl groups, in methyl α-D-mannopyranoside under alkaline conditions, was also studied.