Henry Reaction (Nitroaldol Reaction)

The Henry reaction, also known as the nitroaldol reaction, is utilized to synthesize β-nitroalcohols from aldehydes or ketones and nitroalkanes. Since the proton at the α-position of the nitroalkanes has high acidity, it is easily removed by a base, and the resulting anion is stable due to the nitro group. The anion reacts with a carbonyl compound to afford the corresponding product. The β-nitroalcohols are regarded as useful intermediates since they can be converted into nitroalkenes by dehydration and the hydroxy and nitro group can be converted to other functional groups. A number of asymmetric Henry reactions utilizing various kinds of asymmetric catalysts have been reported in recent years.