Expeditious, large scale preparation of ethyl (R)-5-methyl-3-oxo octanoate via a cross Claisen reaction between N-acyl oxazolidinone derivatives and the magnesium enolate of potassium ethyl malonate

A new and efficient method for the direct conversion of N-acyl oxazolidinones to a β-keto ester is disclosed. The one-pot transformation is effected by the utilization of an excess of Lewis acid along with base and potassium ethyl malonate. This methodology has been applied to the large scale preparation of ethyl (R)-5-methyl-3-oxooctanoate.