Tishchenko Reaction

The Tishchenko Reaction is a disproportionation reaction that allows the preparation of esters from two equivalents of an aldehyde.

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Mechanism

The aluminium alkoxide acts as a Lewis acid to coordinate with one molecule of the aldehyde, and to facilitate the addition of a second equivalent of aldehyde, generating a hemiacetal intermediate:

This species undergoes an intramolecular 1,3-hydride shift that results in the production of the aluminium-coordinated ester.

A potential side reaction is the involvement of one of the alkoxide groups from the catalyst:

This can be minimised, if the reaction is conducted at low temperatures and low catalyst loadings.

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Recent Literature

Catalytic Meerwein-Ponndorf-Verley (MPV) and Oppenauer (OPP) Reactions: Remarkable Acceleration of the Hydride Transfer by Powerful Bidentate Aluminum Alkoxides
T. Ooi, T. Miura, Y. Itagaki, H. Ichikawa, K. Maruoka, Synthesis, 2002, 279-291.

Direct Catalytic Asymmetric Aldol-Tishchenko Reaction
V. Gnanadesikan, Y. Horiuchi, T. Ohshima, M. Shibasaki, J. Am. Chem. Soc., 2004, 126, 7782-7783.