A C-13 nuclear magnetic resonance study of the pyrimidine synthesis by the reactions of 1,3-dicarbonyl compounds with amidines and ureas

Abstract

The detailed mechanistic pathways are elucidated for the reactions of acetylacetone, methyl acetoacetate, and dimethyl malonate with a variety of amidines and ureas. In many cases the identification of a single intermediate allows the definition of the reaction path and identification of two slow steps. Intermediates characterized include ring-closed dihydroxytetrahydropyrimidines, dihydrohydroxypyrimidinones, open-chain enamides, and carbonyl addition compounds.