The Research Of Asymmetric Michael-Aldol Reaction Of ?,?-unsaturated ?-ketoesters And Double Michael Addition Of Divinyl Ketones

Firstly,an efficient double Michael addition of nitromethane to divinyl ketones catalyzed by a chiral primary amine was established in good to high yields(75-99%).Comparing with the previous study via a stepwise manner,most of cyclohexanones were obtained with better enantioselectivities(91-99% ee)and diastereoselectivities(up to >20:1 dr)in a one-pot fashion via our approach.The involvement of basic additive significantly enhanced the reactivity of this cascade sequence.Moreover,a highly stereoselective Michael-Aldol cascade reaction between 2-mercaptobenzaldehydes and ?,?-unsaturated ?-ketoester has been successfully developped in the presence of squaramide.The substituted thiochromanes were obtained in high yields(85-99%),excellent enantioselectivities(90-99% ee)and diastereoselectivities(up to >20:1 dr).Furthermore,the absolute configuration of the desired product was unambiguously determined by X-ray crystallographic analysis.