Asymmetric conjugate addition reaction by the use of ( [formula omitted])-γ-trityloxymethyl-γ-butyrolactam as a chiral auxiliary

Abstract

( S )-γ-Trityloxymethyl-γ-butyrolactam ( 2) serves as a chiral auxiliary in the conjugate addition reaction of the corresponding imide ( 3) of α,β-unsaturated carboxylic acids with Grignard reagents in the presence of CuBrSMe 2 in THF to give, after hydrolysis, the β,β-disubstituted carboxylic acids ( 5) with predictable absolute configuration and high enantiomeric excess.