Reactions Performed in situ During an Oppenauer Oxidation

Reactions Performed in situ During an Oppenauer Oxidation 

A common side reaction during Oppenauer oxidations consists of the base-catalyzed condensation of the carbonyl compound, resulting from the oxidation, with the carbonyl compound used as oxidant. Sometimes, advantage is taken from this side reaction for synthetic purposes. For example, oxidation of primary alcohols with an aluminium alkoxide and acetone results in the formation of an intermediate aldehyde that condenses with acetone, resulting in a synthetically useful formation of an enone.59 

During a synthesis of vitamin A, a primary allylic alcohol is treated with Al(0/-Bu)3 and acetone, resulting in an intermediate aldehyde that condenses in situ to form a synthetically  

Similarly, Nakano et al. have prepared a number of alkylidenecycloke-tones by the oxidation of primary alcohols with cycloketones in the presence of Cp2ZrH2, which operates in a similar manner as aluminium alkoxides.60 

The Oppenauer oxidation is a common side reaction during the condensation of organometallic compounds with aldehydes and ketones, something that very often comes as a surprise for the unaware chemist. This has been observed in condensations of diverse organometallic species, for example chromium,61 Zr62 and Mg63 organometallics. This side reaction 

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