Synthesis and application of new iminopyridine ligands to enantioselective copper(II)-catalyzed Henry reaction

Chiral iminopyridines obtained by reaction between a variety of chiral amines and pyridyl aldehydes or ketones were assessed as catalysts in the enantioselective Henry reaction between nitromethane and 2-methoxybenzaldehyde in the presence of copper(II) acetate. 1-(2-Methoxyphenyl)-2-nitroethanol was obtained in moderate yields and good enantioselectivities (up to 82% ee) under straightforward experimental conditions without the need for air or moisture exclusion. The best enantioselectivity (82% ee) was obtained by an iminopyridine based on a camphane skeleton