Syntheses of [1,2,3]selenadiazolo[4,5-e]benzofuran or benzothiophene, [1,2,3]thiadiazolo[4,5-e]benzofuran or benzothiophene, and 2-benzofuranyl-1,3,4-oxodiazole derivatives

Article abstract of DOI:10.1002/jhet.5570400305

Dehydrogenation of ethyl 3-methyl-4-oxo-4,5,6,7-tetrahydrobenzofuran-2-carboxylate 1 with 2,2′-azobisisobutyronitrile and N-bromosuccinimide gave ethyl 4-hydroxy-3-methylbenzofuran-2-carboxylate 3. Reaction of compounds 3-4 with hydrazine hydrate afforded