Polyfunctional heteroaromatics: A route to dicyanomethylene thiazoles based on the reaction of α-thiocyanatoketones with malononitrile

Abstract

Reactions of α-S-cyanothioketones 6a-c with malononitrile were observed to form 2-(thiazol-2(3H)-ylidene)malononitrile derivatives 7a-c. The thiazole products readily react with aromatic diazonium salts to yield 2-(5-phenylazo-3H-thiazol-2-ylidene)-malononitrile derivatives 8a-c. The malononitrile derivative 8c undergoes a condensation with DMF/DMA to yield thiazolo[5,4-c]pyridazine 12. Reactions of 7a-c with hydrazine hydrate leads to the generation of diaminopyrazoles 9a-c, which react with enaminone 13 to yield the corresponding thiazolylpyrazolo[1,5-a]pyrimidines 14. In addition, reaction of the malononitrile derivative 8a with benzenediazonium chloride readily affords the coupling product 10. © ARKAT USA, Inc.