Catalyst-free, one-pot expeditious synthesis of polyhydroquinolines and 2-amino-4H-chromenes

The present work highlights a rapid, efficient, eco-friendly protocol for synthesizing one-pot polyhydroquinolines via Hantzsch reaction and 2-amino-4H-chromene derivatives under catalyst-free condition. The present mild and greener method uses ethanol: water (1:1) without catalyst at R.T. and 90 degrees C. The structurally diverse substrates were selected to ascertain the ability of the current approach to handle different functional groups, including ketones as one of the substrates. The current methodology is economical and environmentally friendly for the three and four-component reaction of aliphatic, acyclic, aromatic, heterocyclic aldehydes in shorter reaction time, simple workup procedure, no catalyst with excellent yields, and high atom efficiency are the added advantages of this protocol. [GRAPHICS] .