MgO nanoparticles were prepared by an improved sol–gel technique which appeared to have narrow size distributions. The synthesized magnesium oxide nanoparticles were used as an efficient catalyst in aza-Michael reaction for addition of amines to a series of α,β-unsaturated carbonyl compounds and nitro olefins under solvent-free conditions at room temperature to afford high yields of the β-amino carbonyl and β-nitro amines. The catalyst can be recovered and reused at least five successive runs without loss of activity.
Irradiation of β-aminopropiophenones 1 leads to the formation of 2-aminocyclopropanols 2 which can undergo oxidative ringopening to give enaminones 3. The regioselectivity of cyclopropanol formation of the α-benzyl substituted 1 is determined by the preferred charge transfer interaction between the photoexcited benzoyl chromophore and the amino group. The photocyclizations of the α- or β-substituted