Synthesis of some new 2-arylindoles and 2-arylbenzindoles via aza ring closure reactions of 4-fluorobenzylpyridinium bromide and 4-fluorobenzyldimethylsulfonium bromide with aromatic amines

4-Fluorophenacypyridinium bromide and 4-fluorophenacyl-dimethyl sulfonium bromide on refluxing with substituted anilines in presence of dimethylaniline gave 2-arylindoles in 40-70% yields. The reacton of these salts with 1-aminonaphthalene and 2-aminonaphthalene gave 2-arylbenzindoles. The reaction proceeds via the nucleophilic attack of aniline to the carbonyl group of pyridinium and solfonium salts which, in turn, undergo ylide formation after dehydrohalogenation. The structures of all new indoles were confirmed by clemental, IR and NMR spectral analyses.