Asymmetric Michael addition catalysed by sugar-based prolinamides in solvent-free conditions

Sugar-based prolinamides derived from glucosamine have been developed as organocatalysts for the asymmetric Michael addition between cyclohexanones and nitroolefins. Numerous polar and nonpolar solvents and additives have been screened in the current study. The organocatalyst 1c in the presence of benzoic acid as additive catalysed the reaction under neat conditions to afford Michael adducts in high yields (up to 98%) with excellent diastereoselectivities (up to >99:1) and moderate enantiomeric ratios (up to 84:16). (C) 2010 Elsevier Ltd. All rights reserved.