Intra- and intermolecular 1,3-dipolar cycloaddition of sugar ketonitrones with mono-, di-, and trisubstituted dipolarophiles

The 1,3-dipolar cycloaddition of sugar ketonitrones is a useful synthetic procedure to build up nitrogenated quaternary centers in terms of scope (substrate, dipolarophile, inter- and intramolecular versions), yield, and regio- and stereoselectivity. The hybrid ONIOM (B3LYP/6-31G(d):AM1) theoretical method followed by single-point energy calculations at the B3LYP/6-31G(d) level adequately perform to model this cycloaddition for the relatively large ketosugar precursors commonly used.