Synthesis of Conformationally Constrained C-Glycosyl α- and β-Amino Acids and Sugar−Carbamino Sugar Hybrids via Diels−Alder Reaction

[structure: see text] Sugar-derived dienes undergo Diels-Alder reactions with methyl alpha-nitro acrylate and ethyl beta-nitro acrylate to form the corresponding cycloadducts which have been converted into conformationally constrained C-glycosyl alpha- and beta-amino acids. Further, these beta-amino acids are converted into sugar-carbamino sugar hybrid molecules.