Simple and Convenient Approach for Synthesis of Tetrahydroquinoline Derivatives and Studies on Aza-Cope Rearrangement

Abstract

A simple and novel synthesis of 1,2,3,4-tetrahydroquinoline derivatives by polyphosphoric acid–assisted reaction of N-aryl allyl anilines prepared from anilines has been reported. The generality and scope of the approach has been demonstrated by extending it to the synthesis of 1,2,5,6-tetrahydro-4H-pyrrolo[3,2,1-ij]quinoline (lilolidine) and 2,3,6,7-tetrahydro-1H,5H-pyrido[3,2,1-ij]quinoline (julolidine). Further, Lewis acid–mediated aza-Cope rearrangement of various N-aryl allyl anilines has been demonstrated.

Keywords:

• Aza-Cope rearrangement
• julolidine
• lilolidine
• polyphosphoric acid
• 1,2,3,4-tetrahydroquinolines

ACKNOWLEDGMENT

The authors thank Glenmark Pharmaceuticals Limited for granting permission to carry out the research work.

Notes

^a All reactions completed within 10–15 min under a nitrogen atmosphere.