CONDENSED BRIDGEHEAD NITROGEN HETEROCYCLIC-SYSTEMS - SYNTHESIS AND ANTIMICROBIAL ACTIVITY OF THIAZOLO[3',2' 2,3]-AS-TRIAZINO[5,6-B]INDOLES AND ISOMERIC THIAZOLO[2',3'/3,4]-AS-TRIAZINO[5,6-B]INDOLES/

ydro-7-methyl-5H-as-triazino[5,6-b]indole-3-thione 4 on condensation w ith alpha-haloketones gives oylmethylthio-7-methyl-5H-as-triazino[5,6- b]indole hydrobromides 5 which on PPA catalysed cyclisation furnishes ethylthiazolo[3',2':2,3]-as-triazino[5,6-b]indoles 6 and not the angul ar isomer, ethylthiazolo[2',3':3,4]-as-triazino[5,6-b]indoles 8. The u nequivocal synthesis of 8 has also been accomplished. The antibacteria l and antifungal activities of some of the representative compounds ha ve also been evaluated.