Chiral DBFOX/Ph complex catalyzed enantioselective nitrone cycloadditions to α,β-unsaturated aldehydes

1,3-Dipolar cycloadditions of nitrones with alpha-alkyl- and alpha-arylacroleins are catalyzed with the DBFOX/Ph complexes of nickel(II) and magnesium(II) salts to produce the sterically controlled isoxazolidine-5-carbaldehydes, while the reactions with alpha-bromoacrolein are effectively catalyzed with the zinc(II) complexes to produce the electronically controlled isoxazolidine-4-carbaidehydes. Enantioselectivities up to 99.5% ee have been observed in the reactions performed at room temperature.