Enantioselective synthesis of alpha-alkyl-beta,gamma-unsaturated esters through efficient cu-catalyzed allylic alkylations.J Am Chem Soc. 2003 Apr 23; 125(16):4690-1.JA
A method for enantioselective Cu-catalyzed allylic substitution between various alkylzincs and alpha,beta-unsaturated carboxylic esters that bear a gamma-phosphate is reported. These transformations afford alpha-alkyl-beta,gamma-unsaturated carbonyls with regioselectivities of 7:1 to >20:1 (S(N)2':S(N)2) and in 87-97% ee. The utility of the method is illustrated by a convergent total synthesis of topoisomerse II inhibitor (R)-elenic acid.