A Convenient Synthesis of 4‐CF3‐Quinolines from 1‐Trifluoromethyl‐prop‐2‐yne 1‐Iminium Salts and Arylamines

Abstract

AbstractA convenient synthesis of 4‐trifluoromethyl‐quinolines from 1‐trifluoromethyl‐prop‐2‐yne 1‐iminium triflates and anilines in a one‐pot two‐step Michael addition/intramolecular cyclization sequence is reported. With ring‐substituted anilines, a wide range of 4‐CF3‐quinolines bearing additional substituents and functional groups in the C‐2, C‐6, and C‐8 positions were prepared, mostly in high yields. Even a 4‐CF3‐5‐Me‐quinoline could be obtained. From mono‐Boc protected 1,4‐ and 1,3‐phenylenediamine, 2‐aryl‐substituted 6‐amino‐4‐CF3‐quinoline and 7‐amino‐4‐CF3‐quinoline, respectively, were prepared. 4‐CF3‐benzo[h]quinolines were obtained from the mentioned acetylenic iminium salts and 1‐naphthylamine. With N‐monosubstituted aromatic amines such as N‐methylaniline and 1,2,3,4‐tetrahydroquinoline, N‐substituted 4‐CF3‐quinolinium salts and pyrrolo[1,2‐a:3,4‐c']diquinoline derivatives bearing two CF3 substituents could be prepared.