(4-PI+2-PI)-CYCLOADDITION REACTION OF 2-ARYLMETHYLENEAMINOBENZOTHIAZOLEAND (-BENZIMIDAZOLE) AS HETERODIENE TO PHENYLISOCYANATE AND PHENYLISOTHIOCYANATE A FACILE SYNTHESIS OF DIHYDROTRIAZINE

The synthesis of new nitrogen bridged heterocycles 2,3-disubstituted-3,4-dihydro-2H-s-triazin-[2,3-b)-benzothiazol e (-benzimidazole)-2-ones(-2-thiones) 4-11 reported in this work involves (4PI+2PI)-cycloaddition of phenylisocyanate 3a or phenylisothiocyanate 3b as dienophile to 2-arylmethyleneaminobenzothiazoles 1 and (-benzimidazoles) 2 as 1,3-diazabutadiene derivatives (heterodiene). The thermolysis of compounds 1a, 2a in xylene leads to cyclodimer adducts 12,13 through Diels-Alder like reaction .