Collect. Czech. Chem. Commun. 1986, 51, 2214-2221

A novel synthesis of thiazolyl, imidazothiadiazolyl, and thiadiazinyl-2H-1-benzopyran-2-ones

V. Rajeswar Rao, M. S. Rao and T. V. Padmanabha Rao

Department of Chemistry, Kakatiya University, Warangal 506 009, India


3-Acetylcoumarins I with arylthiourea in the presence of iodine gave substituted 3-(2-arylamino-4-thiazolyl)-2H-1-benzopyran-2-ones (IIa-IIc). The structures of these products have been confirmed and they were converted into acetyl derivatives (IId-IIf). Condensation of various 3-(2-bromoacetyl)-2H-1-benzopyran-2-ones (III) with 2-amino-6-substituted thiadiazoles IV in the presence of ethanol and dimethylformamide yielded substituted 3-(2-substituted imidazo[2,1-b]thiadiazol-6-yl)-2H-1-benzopyran-2-ones (VI). Reaction of III with 3-substituted 4-amino-5-mercapto-S-triazole VII resulted in the formation of VIII in a single step.