Crystal Structure of Ethyl 2,4-Dimethyl-1-phenyl-6-thioxo-1,6-dihydropyrimidine-5-carboxylate: The Product from the Reaction of Ethyl 3-Aminocrotonate, Phenylisothiocyanate and Acetic Anhydride

Abstract

The crystal structure of ethyl 2,4-dimethyl-1-phenyl-6-thioxo-1,6-dihydropyrimidine-5-carboxylate (7) has been determined (monoclinic, P21/n, a 12.5543(9); b 7.6345(4); c 16.1568(14) A, β 107.210(9)°) revealing a thioamide functional group instead of the thiazine ethyl (Z)-2,4-dimethyl-6-(phenylimino)-6H-1,3-thiazine-5-carboxylate (5) proposed previously. This has required the revision of the published structure for this multicomponent reaction which now has identified (7), not (5), as the product, supported by NMR and IR analysis. The crystal structure of the major product from the reaction of ethyl 3-aminocrotonate, phenylisothiocyanate and acetic anhydride is ethyl 2,4-dimethyl-1-phenyl-6-thioxo-1,6-dihydropyrimidine-5-carboxylate (shown), not the previously identified ethyl (Z)-2,4-dimethyl-6-(phenylimino)-6H-1,3-thiazine-5-carboxylate.