Regarding the intramolecular cyclization of ethyl (E)- 2-cyano-3-(S-methylisothioureido)- 2-propenoate

Abstract

It is known that, depending on the substituent in the ureido fragment, the intramolecular cyclization of esters of 2-cyano-3-(S-alkylisothioureido)-2-propenooic acid in basic catalysis conditions occurs by two routes to form a mixture of the corresponding 2-alkylsulfanyl-5-cyano-4(3H)-pyrimidinone salts and ethyl 2-alkylsulfanyl-4-amino-5-pyrimidine carboxylates [1-4]. At the same time, from our data, the cyclization reaction of 3-(S-alkyl- isothioureido)-2-cyano-2-propenoates in acid conditions has hardly been studied.