Mechanism of the Hydrolysis of (Z)-4-Benzylidene-2-methyloxazolin-5-one or (Z)-4-Benzylidene-2-phenyloxazolin-5-one Derivatives

Article abstract of DOI:10.1021/jo00207a014

The methyl (1a) and the phenyl (2) derivatives of (Z)-4-benzylideneoxazolin-5-one were hydrolyzed at comparable rates under alkaline conditions.In contrast, the acidic hydrolysis of 2 was at least 10E5 times slower than that of 1a.The Hammett ρ value obtained from the acidic hydrolysis of the phenyl substituted derivatives of 1a was 0.20 +/- 0.09 while that from the corresponding basic hydrolysis was 1.50 +/- 0.11.Methanolysis of 1a under basic conditions produced the methyl ester of (Z)-α-(acetylamino)cinnamic acid, and that under acidic conditions led to products consistent with the attack of methanol at the imine carbon.These results indicate that the alkaline hydrolysis of the oxazolin-5-one derivatives occurs through nucleophilic attack at the carbonyl carbon of the substrate and the acidic hydrolysis through that at the imine carbon.