New many fold 1,2,3-selenadiazole aromatic derivatives

The many fold aromatic ketones 2a-d are versatile compounds for the synthesis of the many fold 1,2,3-selenadiazole aromatic derivatives 5a-d. The preparation starts with the reaction between the many fold bromomethylene benzene derivatives 1a-d and 4-hydroxyacetophenone, which are transformed through the reaction with semicarbazide hydrochloride or ethylhydrazine carboxylate into the corresponding semicarbazones derivatives 3a-d or hydrazones 4a-d. The reaction with selenium dioxide leads to regiospecific ring closure of semicarbazones or hydrazones to give the many fold 1,2,3-selenadiazole aromatic derivatives in high yield.