Transacetylation of Ethyl α-Arylacetoacetates

Abstract

A novel acetylating method using ethyl α-arylacetoacetates was established. Activation of β-keto esters by an aryl group made possible the quantitative transfer of the acetyl group from the keto ester to amines, EtOH and EtSH under mild conditions. The chemoselective acetylation of diamines and aminoalcohols was conducted.
The introduction of an aryl group at the α-position caused various factors to act in concert with good effect, as follows : a) stabilization of the enol form, b) increased acidity of the enol OH group, c) protection of the acetyl group from attack of sterically hindered nucleophiles and d) promotion of the elimination of departing groups by electronic stabilization and steric repulsion.