Reactions of 3,4-Dichloro-N-R-maleimides with Substituted 2-Thiouracils |
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Authors: | Yu. M. Volovenko G. G. Dubnina A. N. Chernega |
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Affiliation: | (1) Taras Shevchenko Kiev National University, Kiev, 01033, Ukraine;(2) Institute of Organic Chemistry, National Academy of Sciences of Ukraine, Kiev, 02094, Ukraine |
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Abstract: | Reactions of 3,4-dichloro-N-R-maleimides with substituted thiouracils at 40°C gave a 1:1 mixture of isomers of pyrrolothiazolopyrimidinetriones. Under conditions of thermodynamic control (100°C, 5 h) only pyrrolo[3',4':4,5]thiazolo[3,2-a]pyrimidine-4,6,8-triones were formed, hydrolysis of which followed by decarboxylation gave 5-oxo-5H-thiazolo[3,2-a]pyrimidine-2-carboxamide. The structure of N2-phenyl-6-methyl-5-oxo-5H-thiazolo[3,2-a]pyrimidine-2-carboxamide was confirmed by X-ray crystallography. Analogous cyclization of 3,4-dichloro-N-R-maleimides with 2-thioxoquinazol-4-one also gave a mixture of two isomers which were successfully separated by fractional crystallization. |
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Keywords: | 7-R-2-R2-3-R1-7,8-dihydro-4H,6H-pyrrolo[3',4':4.5][1,3]thiazolo[3,2-a]pyrimidine-4,6,8-triones N2-R-6-R1-5-oxo-5H[1,3]thiazolo[3,2-a]pyrimidine-2-carboxamide nucleophilic substitution in 3,4-dichloro-N-R-maleimides |
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