Asymmetric Intramolecular Conjugate Addition Nitro-Mannich Route to cis-2-Aryl-3-nitrotetrahydroquinolines

Reductive cyclization of 2-iminonitrostyrenes (froth the condensation of 2-aminostyrenes with an aldehyde and subsequent nitration of the alkene) using a bifunctional thiourea catalyst and tert-butyl-Hantzsch ester leads to an intramolecular conjugate hydride addition nitro-Mannich reaction to give the corresponding cis-2-aryl-3-nitrotetrahydroquinolines as single diastereoisomers in high yields and enantioselectivities.