Preparation of quinolines by reduction of ortho-nitroarenes with zinc in near-critical water

Abstract

We report a preparation of quinoline 2 and indole 4 derivatives by reduction of suitably functionalised o-nitroarenes with Zn powder in H₂O at 250°C. The process involves the reduction of the nitro group to an amino group followed by insitu cyclisation with a carbonyl or alcohol moiety in an aqueous medium. The amount of hydroquinoline 3 produced depends on the nature of the carbonyl moiety of the nitroarene.