FUSED THIAZOLES FROM 3-AMINO-THIAZOLINE-2-THIONES: SYNTHESIS OF PYRAZOLOTHIAZOLE AND THIAZOLO-1,3,4-THIADIAZINE DERIVATIVES

Article abstract of DOI:10.3987/R-1987-05-1323

Two approaches for the preparation of a number of pyrazolo<5,1-b>thiazoles are reported.The first involves reaction of 3-amino-4-phenyl-thiazoline-2-thione 1 with phenacyl bromides to give thiazolo<2,3-b>-1,3,4-thiadiazines 2 which by action of triethylamine are converted into the pyrazolo<5,1-b>thiazoles 4.The second is based on the reaction of 3-amino-2-methylthio-4-phenylthiazolium cation 5 with activated acetonitriles to give 7-substituted 6-amino-3-phenylpyrazolo<5,1-b>thiazoles 7.