Novel synthesis of biologically active indolo [3,2-C] isoquinoline derivatives

Indole-2-carboxylates are refluxed with hydrazine hydrate to form 5-substituted-3-phenylindole-2-carboxyhydrazides. These are again converted to corresponding indole-2-carboxyazides. Azides are further converted into carbamates and finally these carbamates are cyclized to form the respective substituted 6H, 11H-indolo [3,2-C] isoquinolin-2-ones (1a-c). These (1a-c) were reacted with phosphorus pentasulfide in refluxing pyridine to yield the respective thiones (2a-c). These thiones (2a-c) on reaction with chloroacetic acid and sodium acetate in acetic acid under refluxing temperature for 5 h yielded isoquinoline-thioacetic acids (3a-c). Compounds (3a-c) on reaction with orthopheneylene diamine dihydrochloride in ethylene glycol at refluxing temperature yielded substituted indolo [3,2-C] isoquinolin-2′-yl sulfanyl methylene benzimidazoles (4a-c).