Nitroaldol reaction

The Nitroaldol reaction or Henry reaction is an aldol type reaction between an aldehyde and nitromethane. The nucleophilic addition step is base catalysed and may be followed by an elimination reaction with removal of water when an acidic alpha proton is present. The reaction product is a beta-hydroxy nitro-compound or a nitroethylene compound.

For example benzaldehyde reacts with nitroethane to trans-1-phenyl-2-methyl-2-nitroethene. With ammonium acetate as a catalyst this dry media reaction proceeds with microwave irradiation under 7 minutes.

An enantioselective aldol addition product can be obtained in asymmetric synthesis by reaction of benzaldehyde with nitromethane and the a catalyst system consisting of a zinc triflate salt / the base diisopropylethylamine (DIPEA) and as chiral ligand is the N-methyl derivative of (+)-ephedrine (NME).

A diastereoselective variation of this reaction is depicted below :