The action of amines on citraconic anhydride. X-Ray crystal structure of (Z)-2-methyl-3-pyrrolidinocarbonylpropenoic acid

Abstract

The reaction of citraconic anydride with 15 primary and secondary amines gave mixtures of isomeric citraconamic acids (2) and (3), in which the former predominated. The more abundant isomers rearranged to the thermodynamically stable N-substituted (Z)-2-methyl-3-carbamoylpropenic acids (3) on warming. The structure of the pyrrolidide (3q) was confirmed by X-ray analysis. An unsuccessful attempt to convert the pyrrolidide into 4-methyl-6-pyrrolidino-1,3-oxazin-2-one (7) is described.