Efficient acylation and transesterification catalyzed by dilithium tetra-tert-butylzincate at low temperatures

Abstract

The acylation and transesterification of alcohols with vinyl acetate and carboxylic esters were investigated in the presence of a catalytic amount (1–10mol%) of dilithium tetra-tert-butylzincate (TBZL) as a catalyst. The acylation proceeded quantitatively at 0°C within 1h. The transesterification occurred for a wide range of combinations of esters and alcohols at 0 to −40°C. To the best of our knowledge, this is the first successful transesterification at such low temperatures. The time–conversion plots for the transesterification show that the reaction reached equilibrium within 5min at 0°C. The reaction proceeded quantitatively by addition of molecular sieves 4A. In addition, the transesterification proceeded even in the presence of H2O and amines.