In our recent communications! , 2 we have shown that oxidation of quaternary 2,4,6-triphenylpyridinium salts with alkaline solution of potassium ferricyanide gives high yields of pyrrole derivatives type 1. On the contrary, quaternary 2,3,4,5,6- -pentaphenylpyridiniuJ11 salts gave3 tetraphenylpyrro]es 11 under the same conditions. Jt was interesting to find whether also the quinolinium salts IlIa-Illc would undergo a ring contraction to give indole derivatives. The ...
