Synthesis of β-aminocarbonyl compounds catalyzed by nitrogen and sulfur doped carbon sphere (NS-doped-CS) via multicomponent Mannich reactions in water

β-Amino carbonyl compounds are attractive targets for chemical synthesis,because they are widely used as biologically active compounds and are important synthesis for a variety of pharmaceuticals.A highly diastereoselectivemulticomponentMannich reaction between cyclohexanone, aromatic aldehydes and amines in water is described.A novel heteroatom doped carbon sphere catalyzed this reaction. Reactions proceeded in good to high yields with an excellentdiastereoselectivity (Figure 1). The best selectivity was obtained where there are weak electron donating and electron-withdrawing groups on the aldehyde. The rate formation of Mannich product is decreased when strong electron-withdrawing groups and/or electron-releasing groups are present on aldehyde; in these cases selectivity is improved if an electron-donating group is present on the amine. The catalyst is recoverable and reused for five times without significant decrease in its activity.