The Gould-Jacobs reaction of 5-amino-2,1,3-benzoselenadiazole afforded solely angularly annulated 8-substituted 9-oxo-6,9-dihydro-[1,2,5]selenadiazolo[3,4-f]quinoline derivatives.In the course of thermal cyclization no linear products were observed.Nucleophilic vinylic substitution of activated enolethers with 5-amino-2,1,3-benzoselenadiazole was also studied.

An effective method for the synthesis of 4-amino-2,1,3-benzoselenadiazole (4) has been described. Reduction of readily available 4-nitrobenzothiadiazole 6 with SnCl2 center dot 2H(2)O afforded 1,2,3-triaminobenzene dihydrochloride 2. The latter upon treatment with aqueous SeO2 solution provided desired amine 4. Nucleophilic vinylic substitution of activated enol ethers 7 with amine 4 led to (benzoselenadiazol-4-yl-amino)methylene derivatives 8. Thermal cyclization of derivatives 8a-c, e, f under Gould-Jacobs reaction conditions gave angularly annelated 7-(non)substituted selenadiazolo[3,4-h]quinolones 9. Acid hydrolysis of etyl ester 9c afforded corresponding acid 10. All prepared selenadiazoloquinolones were tested for antimicrobial activity. (C) 2010 Elsevier Ltd. All rights reserved.

Electron impact mass spectra of variety of eight 4-substituted and eight 5-substituted benzoselenadiazoles are presented and their spectral fragmentations are discussed. New mass spectra containing selenium in heterocyclic azole atom containing ring.