作者:S. G. Pil'o
DOI:10.1023/a:1023333011230
日期:——
Enamides of the general formula Cl2C=C(X)NHCOR1, where X = CN, COOAlk, CONH2, P(O)(OEt)(2), P(O)Ph-2, PPh3 Cl-, were treated in succession with alkane- or arenethiols and silver carbonate to obtain 5-alkyl(aryl)thio-2-R-1-4-X-1,3-oxazoles with high selectivity. The latter were converted into the corresponding sulfonyl derivatives. Unlike 2-acylamino-3,3-dichloroacrylonitriles which react with sodium hydrogen sulfide in a nonselective fashion, reactions of derivatives like Cl(ArS)C=C(CN)NHCOR1 with NaHS lead to hitherto unknown 5-arylthio-4-thiocarbamoyl-2-R-1-1,3-oxazoles whose structure was confirmed both by spectral methods and by cyclocondensation with bromoacetophenone according to Hantzsch. Heating of some 2-aryl-5-mercapto-4-X-1,3-oxazoles with benzenethiols results in recyclization into the corresponding 2,4-disubstituted 5-arylthio-1,3-thiazoles, presumably due to prototropic tautomerism in the 5-mercapto-oxazole fragment.