Mechanistic studies in the chemistry of urea. Part 5. Reaction of urea, 1-methylurea, and 1,3-dimethylurea with 1-phenylpropane-1,2-dione in acid solution

Abstract

In acid solution 1-phenylpropane-1,2-dione reacts with urea to give a bicyclic compound (2), with 1,3-dimethyl-and 1,3-diethyl-urea to give the spiro-compounds (4) and (10), and with 1-methylurea to give a bicyclic compound of possible structure (11), (12), or (13). Mechanisms for formation of the first three compounds are suggested and the tendency of the diol intermediates to eliminate water is discussed. The methyl group of the dione is one site of reaction.