Protein-Mediated Nitroaldol Addition in Aqueous Media. Catalytic Promiscuity or Unspecific Catalysis?

A high efficient and environmentally friendly procedure for the production of aromatic and heteroaromatic β-nitroalcohols has been developed. This synthetic approach involves the condensation of an appropriate aldehyde with 1-nitroalkanes in aqueous media using as catalyst the inexpensive carrier protein Bovine serum albumin (BSA). According to the experimental data, the Henry reaction between aromatic aldehydes and nitroalkanes in aqueous media proceeds by unspecific protein catalysis rather than catalytic promiscuity. By proper choice of the reaction conditions, the corresponding nitroalcohols were obtained in yields up to 91% at 30 °C. Catalyst recycling and scale-up of the reactions have been considered as important factors, in order to show this methodology as a valuable synthetic approach.