Condensed bridgehead nitrogen heterocyclic systems: Synthesis and bioactivity of 2,3-dihydrothiazolo[3 ',2' :2,3]-<i>as</i>-triazino[5,6-<i>b</i>]<i> </i>indole, 2,3-dihydro-4<i>H</i>[1,3]thiazino [3',2' : 2,3]-<i>as</i>-triazino[5,6-<i>b</i>]indole and quinoxalino[2',3' :4,5]thiazolo[3,2-<i>b</i>]indolo[2,3-e]<i>-as-</i>triazine and their isomeric systems

Abstract

2,3-Dihydro-8-isopropyl-5<i>H</i>-<i>as</i>-triazino[5,6-<i>b</i>]indole-3-thione <b>2</b> on condensation with 1,2-dibromoethane, 1-3-dibromopropane and 2,3-dichloroquinoxaline gives the cyclized products, 7- isopropyl-2,3-dihydrothiazolo[3',2':2 ,3]-<i>as</i>-triazino[5,6-<i>b</i>] indole <b>3</b>, 2,3-dihydro-8-isopropyl-4<i>H</i>-[1,3]thiazino[3',2':2,3]-<i>as</i>-triazino[5,6-<i>b</i>]indole <b>4</b> and 9-isopropylquinoxalino [2' ,3' :4,5]thiazolo[3,2-<i>b</i>] indolo[2 ,3-<i>e</i>]-<i>as</i>-triazine <b>5</b>, respectively and not the angular isomers, 7-isopropyl-2,3-dihydro[2' ,3':3,4]-<i>as-</i>triazino[5,6<i>-b</i>] indole <b>6</b>, 8-isopropyl-1<i>H</i>-2,3-dihydro[1,3]thiazino[2',3' :3,4]-<i>as</i>-triazino[5,6-<i>b</i>] indole <b>7</b> and 3-isopropylquinoxalino

[2',3':4,5]thiazolo[2,3-<i>c</i>] indolo[2,3-<i>e</i>]-as- triazine <b>8</b>. The unequivocal synthesis of the latter <b>6</b>, <b>7</b> and <b>8</b> has been accomplished by reaction of 5-isopropylisatin-3-thiosemicarbazone <b>1</b> with 1,2-dibromoethane, 1,3-dibromopropane and 2,3-dichloroquinoxaline, respectively. The bioactivity of the synthesized compounds have also been evaluated.