Influence of phase transfer catalyst structure on the E:Z ratio in the O-alkylation of an enolate

Abstract

Both C-  s. O-alkylations and Z s. E enol ether formation from 2-methyl-1,3-diphenylpropane-1,3-dione (1) can be influenced by the structure of the phase transfer catalyst. O-Methylation is the major process in the PTC reaction of 1 with dimethyl sulfate. The E:Z product ratio can be varied between roughly 1:1 and 4:96 by use of different catalysts. This is only the fifth type of conversion in which the catalyst structure can exert a decisive influence.