In the conventional Tishchenko reaction an aluminum alkoxide reagent is used to mediate the transformation of two aldehydes into an ester. In recent years, there have been new examples in which the given reaction was catalyzed using homogeneous transition metal complexes. We use density function theory (DFT) to investigate possible mechanisms in this area. We focus on the octahedral dihydride catalyst [Rh(PhB(CH2PPh2)3)(H)2(NCMe)] developed by Tejel and coworkers. We consider two possibilities: (i) an inner-sphere mechanism starting with substitution of the acetonitrile ligand by an aldehyde, and (ii) an outer-sphere mechanism starting with direct hydride transfer from the metal to the aldehyde. Despite the fundamental differences, the computed energy profiles suggest the two mechanisms can be competitive.

Mechanism of the Tishchenko reaction catalyzed by an octahedral d6-rhodium dihydride catalyst

255th National Meeting (2018)

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