Rh(I)-catalysed Regio-and Enantioselective Allylic Alkylation Of Meldrum's Acid

Meldrum's acid is a kind of common organic compound and widely used in organic synthesis because of its unique structure,electrophilicity and nucleophilicity.Meldrum's acid and its derivatives can commonly be used in Intramolecular Friedel-Crafts acylation and asymmetric Michael addition reactions.However,the reaction of asymmetric allyl substitution of Meldrum's acid as a nucleophile has been rarely reported.At the same time,the transition metal-catalyzed asymmetric allyl substitution reaction is an efficient and practical method for building carbon-carbon bonds and obtaining chiral compounds.After literature research,we found that there is no transition metal that can well catalyze the asymmetric allyl substitution reaction between Meldrum's acid and aliphatic allyl carbonate.In view of the fact that Meldrum's acid compounds can be easily converted,it is of great significance to develop a method that can easily obtain chiral allyl-substituted Meldrum's acid derivatives.Herein,a Rh(I)-catalyzed highly regio-and enantioselective allylic alkylation of Meldrum's acid with racemic allylic substrates bearing alkyl groups has been developed.The reaction provides a simple and practical method for obtaining chiral allyl substituted Meldrum's acid derivatives with high regioselectivity(b / l > 20: 1)and enantioselectivity.The applying of chiral bisoxazopinephosphine ligand is essential for the high yields and selectivities.This method provides a rapid accesss to various b-alkyl-?,?-unsaturated carboxylic acid and its derivatives.