Study of reaction of thiourea with ethyl 3-oxobutanoate

Abstract

Base-catalyzed formation of 6-methyl-2-thiouracil (III) by reaction of thiourea (I) with ethyl 3-oxobutanoate (II) involves N-(3-oxobutanoyl)thiourea (XI) as the reaction intermediate. In acid medium the compounds I and II do not react. In contrast to literature data, base-catalyzed cyclization of ethyl 3-thioureido-2-butenoate (IV) does not produce the compound III, but produces 2-amino-4-methyl-6-oxo-1,3-thiazine.