Highly diastereoselective indium-mediated synthesis of β-lactam carbohydrates from imines

A simple and very effective approach to versatile carbohydrate β-lactam synthons of predictable absolute configuration has been developed. The procedure, which is based on the indium-mediated reaction of imines and bromoesters, was applied to the enantioselective synthesis of 3-monosubstituted and 3-disubstituted β-lactams from readily available carbohydrates. The opening of the β-lactamic ring gave rise to the corresponding sugar-derived β-amino acids. Transformation of the β-lactams into the corresponding azetidines was also achieved.