An intramolecular nitro-Mannich route to functionalised tetrahydroquinolines

A simple protocol for the diastereoselective synthesis of 3-nitrotetrahydroquinolines has been developed using an intramolecular nitro-Mannich reaction. In situ formation of an imine generated from treatment of 2-(2-nitroethyl)phenylamine with an aldehyde, in EtOH at room temperature, and subsequent addition of NH4OH, led to the formation of trans-products in high yield and diastereoselectivity for 15 representative examples.