REACTION OF OXIMES WITH DIMETHYL CARBONATE - A NEW ENTRY TO 3-METHYL-4,5-DISUBSTITUTED-4-OXAZOLIN-2-ONES

The reaction of ketone oximes with dimethyl carbonate (DMC) carried ou t in an autoclave at 180-190-degrees-C and in the presence of K2CO3 yi elds 3-methyl-4,5-disubstituted-4-oxazolin-2-ones. The reaction can be applied to both aliphatic and aromatic ketone oximes, provided that a methylene group be present near the C=N bond. Nonoptimized yields ran ge from 22 to 48%. The reaction seems to be a [3,3] sigmatropic rearra ngement where DMC plays a key role in causing the initial N-methylatio n of the oximes.