Activated nitriles in heterocyclic synthesis: Syntheses of thiazole,pyrazole and 4H-1,4-benzothiazine derivatives

4-Arylazo-3-phenyl-5-aminopyrazoles (5a,b) and substituted hydroxythiazoles8a,b were synthesized from the reaction of4a,b with hydrazine hydrate and mercaptoacetic acid respectively. Compounds5a,b and8a,b were also obtained from coupling of2a,b with6 and7, respectively. 4H-1,4-Benzothiazine11 was prepared from1 and10. The reaction of the diazonium salts2a-c with diethyl 3-amino-2-cyanopent-2-en-1,5-dicarboxylate12 was also reported.