Collect. Czech. Chem. Commun. 1999, 64, 1307-1315

Synthesis of Alkyl- and Phenyl-2-thiouracils and 1,3-Thiazin-4-ones by Nucleophilic Substitution of Unsymmetrical Thioureas with 3-Chloropropenoates

Lars F. Jalander* and Jan-Erik Lönnqvist

Department of Organic Chemistry, Åbo Akademi University, Biskopsgatan 8, FIN-20500 Åbo, Finland


Unsymmetrically substituted thioureas and ethyl (E)- and (Z)-3-aryl-3-chloro-2-cyano- propenoates (1a) and (1b) gave after nucleophilic vinylic substitution and cyclisation two isomers of 1,3-disubstituted 6-aryl-5-cyano-2-thiouracil derivatives, 3a-3i and 4a-4i. Substituted 1,3-thiazin-4-ones 5a-5d were formed in moderate to good yields when monosubstituted thioureas were allowed to react under similar conditions.

Keywords: 2-Thiouracils; 1,3-Thiazin-4-ones; Thioureas; Cyclization; Nucleophilic substitutions; Pyrimidines.