Cinnolines. Part XI. Quaternisation of 3- and 4-phenylcinnolines and reduction of some methylcinnolinium salts

Abstract

3-Phenylcinnoline quaternises with methyl iodide to give 1-methyl-3-phenylcinnolinium iodide and a small amount of its 2-methyl isomer, whereas only the 2-methiodide is isolated from quaternisation of 4-phenylcinnoline. 1-Methyl-3-phenylcinnolinium iodide is reduced electrolytically, or with sodium borohydride, to 1,4-dihydro-1-methyl-3-phenylcinnoline and this is reduced polarographically to 2-o-methylaminophenyl-1-phenylethylamine, which is also obtained directly from the quaternary salt by reduction with amalgamated zinc and hydrochloric acid. Reduction of 1,3-dimethylcinnolinium iodide by the Clemmensen method, however, gives 1,2-dimethylindole and 1,2-dimethylindoline while 2-methylcinnoliniumiodides give the corresponding indole and indoline.