Asymmetric nitroaldol reaction catalyzed by a chromium(III)–salen system

Chiral chromium(III)–salen-type complexes derived from 1,2-diaminocyclohexane and 1,2-diphenylethylenediamine were found to catalyze the enantioselective Henry reaction. Various arylaldehydes, trans-cinnamaldehyde, and cyclohexanecarbaldehyde reacted with nitromethane in the presence of (i-Pr)₂NEt and salen–CrCl (2 mol %) to give the corresponding adducts in 40–76% ee and in moderate to good yields.