作者:Girts Kaugars、James P. Atherton、Fusen Han
DOI:10.1021/jo00032a014
日期:1992.3
The reaction of 5-(arylamino)-1,2,3,4-thiatriazoles 1 with isocyanates initially gives 1,2,3,4-thiatriazol-5-ylureas 3 which can be isolated when the aryl group has o-alkyl substituents. Compounds 3 rearrange to 21 in the presence of triethylamine and then react with the second equivalent of isocyanate to give (4-aryl-2-alkyl-3-oxo-1,2,4-thiadiazolidin-5-ylidene)ureas 12 rather than the (3-oxo-DELTA(4)-1,2,4-thiadiazolin-5-yl)ureas 7 which had been proposed previously.1 The latter compounds, prepared from 8 and isocyanates, also rearrange to 12. Mechanisms incorporating these observations are proposed (Schemes IV and VI). The structure of 12 was confirmed by single-crystal X-ray analysis of [4-(2,6-dimethylphenyl)-2-methyl-3-oxo-1,2,4-thiadiazolidin-5-ylidene]methylurea 12baa.