Synthesis of β-Keto Esters by Carbonylation of Halomethylketones

A number of β-keto esters were synthesized by Pd-catalyzed carbonylation of halomethylketones in the presence of tributylamine in 68-86% yields. The reaction is completed in 2 hours at 110 °C and 10 bar CO pressure. Chloromethylketones are carbonylated selectively while 2-bromoacetophenone is partly reduced to acetophenone as a byproduct. The reaction can be carried out at atmospheric pressure though the rate stays low. The reaction mechanism is discussed.