SYNTHESIS OF SUBSTITUTED 2,5-BIS(1,3,4-OXADIAZOLYL/THIADIAZOLYL/1,2,4-TRIAZOLYL)INDOLES AND STUDY OF THEIR BIOLOGICAL-ACTIVITIES

Abstract

Diethyl substituted indole-2,5-dicarboxylates (1) are reacted with hydrazine hydrate to get the substituted indole-2,5-dicarbohydrazides (2) which on reaction with benzaldehyde give the respective hydrazones (3). The latter are cyclised using FeCl3 to get 2,5-bis(5-phenyl-1, 3, 4-oxadiazol-2-yl)indoles (4). The hydrazides (2) when refluxed with ethyl orthoformate afford the 2,5-bis(1, 3, 4-oxadiazol-2-yl)indoles (6). These compounds (6) are also obtained by reacting 2 with formamide to get the corresponding N-beta-formyl derivatives (5), followed by cyclodehydration of 5 with POCl3. Treatment of 2 with carbon disulphide and potassium hydroxide furnishes the 2,5-bis(4, 5-dihydro-5-thiono-1, 3, 4-oxadiazol-2-yl)indoles (7) in moderate yields. Refluxing of 2 with substituted phenyl isothiocyanates afford the thiosemicarbazides (8) which are converted into 2,5-bis(5-phenylamino-1, 3, 4-oxadiazol-2-yl)indoles (9), 2,5-bis(5-phenylamino-1, 3, 4-thiadiazol-2-yl)indoles (10) and 2,5-bis(1-phenyl-5-mercapto-1, 2, 4-triazol-3-yl)indoles (11). Several compounds exhibit interesting antibacterial activity.