N ‐Azolylmethyl ketones as building blocks in heterocyclic synthesis: Synthesis of new polyfunctionally substituted azolylarylazophenols, azolylpyridones and azolylthiophenes

The title compounds 1a‐b and 2 reacted with 2‐arylhydrazonopropanals 3a‐c to yield polyfunctionally substituted azolylarylazophenols 5 and 8. The reaction of 1b and 2 with phenylisothiocyanate in the presence of α‐haloketones afforded the azolylthiophenes 12a,b and 13a,b. The reaction of 20 with α‐haloketone afforded 5‐benzotriazol‐1‐yl‐6‐methyl‐2‐(2‐oxopropylsulfanyl)nicotinonitrile 21 that was utilized as building blocks for the synthesis of condensed pyridines. Compound 21 was condensed with dimethylformamide dimethylacetal to yield thieno[2,3‐ b ]pyridin‐3‐yl‐ N , N ‐dimethylformamidine derivative 22. This was further cyclized with sodium hydride to 1 H ‐fhieno[2,3‐ b ; 4,5‐ b' ]dipyridin‐4‐one derivative 23.