Sugar-lactams have found application as glycosidase inhibitors, synthetic precursors of iminosugars and they are structural components of natural products. The synthesis of beta-D-glucopyranosidurono-6,1-lactams from glucuronic acid derivatives are described. NMR data and X-ray crystal structures indicate that the sugar-lactams adopt distorted (1)C4 conformations in solution and in the solid state.