Catalytic enantioselective [3 + 2]-cycloadditions of diazoketone-derived aryl-substituted carbonyl ylides

An evaluation of α-aryl-α-diazodiones in tandem carbonyl ylide formation−enantioselective [3 + 2]-cycloaddition reactions is described. Such substrates were designed to allow investigation of the electronic characteristics of the dipole upon asymmetric induction. Intramolecular cycloadditions (with a tethered alkene dipolarophile) were found to occur in good to quantitative yields, with a difference in ee exhibited by the two electronically different diazodiones 8 and 9. Intermolecular cycloadditions using diazodiones 12 and 13 with DMAD and arylacetylenes 16−18 again demonstrated that electronics play a key role in determining the outcome of the cycloaddition reactions. Enantioselectivities of up to 76% were observed.