Hydrogen autotransfer

28 November 2008 - Strategies

What: Hydrogen autotransfer. An organic reaction activated by a preliminary hydrogen abstraction step and followed by a hydrogen addition step (Review DOI). First successful implementation by Edwards at al. in 2002 (DOI) in a so-called indirect Wittig reaction

and by Taguchi et al. (DOI) in 2004, allowing the direct displacement reaction of an electrophilic alcohol by a nucleophilic carbon acid for example in the reaction of 2-octanone with butanol in presence of sodium hydroxide and a iridium catalyst. Both reactions require catalytic amount of base and metal.

The alternative for this particular reaction would be tosylation (= activation) of the alcohol and use of stoichiometric base.
Also known as: hydrogen borrowing

Extension of: transfer hydrogenation (hydrogen donor is a reagent, not in-situ generated from substrate). The reaction is also a type of domino reaction.
Scope: The hydrogen autotransfer methodology has been applied in Knoevenagel reactions for example (Pridmore et al. 2008 DOI):