1-Methyl-4-methyloxycarbonyl-2-pyrrolidone 1-Methyl-5-oxo-3-pyrrolidinecarboxylic acid methyl ester 3-Pyrrolidinecarboxylic acid, 1-methyl-5-oxo-, methyl ester 5-22-06-00040 (Beilstein Handbook Reference) 59857-86-2 BRN 0473460