New spiro and condensed heterocyclic systems: 2,5 ' (H)-dioxospiro {indoline-3,8 ' (7 ' a H) pyrimido [4 ',5 ': 4,5] thiazolo [3,2-a] quinazoline}-10' (9 ' H) thione & 16(H)-oxoindolo [2 '',3 '': 7 ',6 '] diazepino [4 ',5 ': 4,5] thiazolo [3,2-a] quinazoline-7(9H) thione and their linear isomers

2,5'(H)-Dioxospiro {indoline-3,8' (7'a H) pyrimido [4',5':4,5] thiazolo [3, 2-a] quinazoline-10' (9'H) thione (6a) and 16(H)-oxoindolo [2",3" : 7',6'] [1, 3]-diazepino [4',5':4,5] thiazolo [3,2-a] quinazoline 7(9H)-thione (7a) ; their dibromo compounds (6b) and (7b) respectively; [2,11'(H)-dioxospiro {indoline-3,4'(4'a H) pyrimido [4',5'. 4,5] thiazolo [2,3-b] quinazoline}-2 ' (3'H)-thione (8a) and 10(H)-oxoindolo [2",3":7',6'] [1,3] diazepino [4',5 ':4,5] thiazolo [2,3-b] quinazoline-7 (5H)-thione (9a); their dibromo compo unds (8b) and (9b) respectively have been synthesized by the condensation o f 2-(2'-oxo-3'-indolinylidene) thiazolo [3,2-a] quinazoline-1,5 (2H, 5H)-di one (4a), and its dibromo derivatives (4b), 2-(2'-oxo-3'-indolinylidene) th iazolo [2,3-b] quinazoline-3,5 (2H, 5H)- dione (5a) and its dib;omo compoun ds (5b) respectively with thiourea. (4a) and (4b) were obtained by the reac tion of thiazolo [3,2-a] quinazoline-1,5 (2H, 5H)- dione (2a) and its dibro mo compounds (2b) with isatin and similarly (5a) and (5b) were obtained fro m thiazolo [2,3-b] quinazoline-3,5 [2H, 5H]-dione (3a) and dibromo compound (3b) respectively with isatin. 2-Thioxo-4-quinazolone (1a) produced (2a) a nd (3a) and 6,8-dibromo-2-thioxo-4-quinazolone (1b) produced (2b) and (3b) on cyclocondensation with chloroacetic acid. The products have been charact erized by elemental analysis and spectral data.