ATP3 and MTP3: Easily Prepared Stable Perruthenate Salts for Oxidation Applications in Synthesis

The Ley-Griffith tetra-n-propylammonium perruthenate (TPAP) catalyst has been widely deployed by the synthesis community, mainly for the oxidation of alcohols to aldehydes and ketones, but also for a variety of other synthetic transformations (e.g. diol cleavage, isomerizations, imine formation and heterocyclic synthesis). Such popularity has been forged on broad reaction scope, functional group tolerance, mild conditions, and commercial catalyst supply. However, the mild instability of TPAP creates preparation, storage, and reaction reproducibility issues, due to unpreventable slow decomposition. In search of attributes conducive to catalyst longevity an extensive range of novel perruthenate salts were prepared. Subsequent evaluation unearthed a set of readily synthesized, bench stable, phosphonium perruthenates (ATP3 and MTP3) that mirror the reactivity of TPAP, but avoid storage decomposition issues.