Phase-Transfer-Catalyzed EnantioselectiveAlkylation of α-Benzoyloxy-β-Keto Ester

Highly enantioselective alkylation of tert-butyl 2-benzoyloxy-3-oxobutanoate could be realized by the use of N-spiro chiral quaternary ammonium salt as phase-transfer catalyst, as a complementary approach to the asymmetric hydroxylation of α-alkyl-β-keto esters.