Synthesis of “Click BOX” ligands and preliminary results on their application in the asymmetric copper catalysed Henry reaction of o-methoxybenzaldehyde

Abstract

Two new chiral “click BOX” ligands have been synthetised with high yields starting from commercially available dimethyl propargylmalonate and optically pure alkanolamines, followed by copper catalysed cycloaddition (CuAAC) and oxazoline ring formation. Catalytic activity of the new ligands has been tested in the copper mediated Henry addition. The model reaction between nitromethane and o-anisaldehyde affords the related 1-(2-methoxyphenyl)-2-nitroethanol in high yields (up to 92%) and moderate enantioselectivities (up to 67% e.e.) under straightforward experimental conditions.