Meerwein-Ponndorf-Verley Reduction

In the 1920s, three researchers working independently carried out the reduction of carbonyl compounds using aluminum alkoxides. In 1925, Hans Meerwein successfully reduced aldehydes with ethanol in the presence of aluminum ethoxide, and in the same year, Albert Verley reduced ketones using both aluminum ethoxide and isopropoxide. Then in 1926, Wolfgang Ponndorf realized that reduction of both aldehydes and ketones generally used a variety of metal alkoxides, and was also completely reversible. Subsequently, the reduction of aldehydes and ketones using metal alkoxides such as aluminum isopropoxide became known as the Meerwein-Ponndorf-Verley reduction (MPV). The reverse reaction, where alcohols are oxidized to aldehydes and ketones, became known as the Oppenauer oxidation.

As the MVP reaction is completely reversible, removal of the lower boiling ketone or addition of excess isopropyl alcohol is required to shift the equilibrium to the right. However, the reaction is very chemoselective for aldehydes and ketones, and other functional groups such as esters and acetals are not changed. This is the great advantage of this reaction as compared to the use of metal hydride reducing agents.

This highly selective reduction has been used in a myriad of synthesis projects, including that of the furochromone ammiol, and in the determination of the stereochemistry of rutamycin antibiotics through the asymmetric synthesis of the known bicyclic degradation product.