Palladium-catalyzed vicinal oxidation has emerged as an attractive approach for making valuable products from simple and readily available olefins. For example, diamination and aminooxy-genation of olefins have been achieved based on the Pd(II)/Pd-(IV) catalyst cycle, a mechanistic design that has garnered significant attention as a result of Sanford's efforts.5 Despite the prevalence of 1,2-dioxygenated motifs in various organic architectures, a corresponding Pd(II)/Pd(IV) dioxygenation of alkenes has not previously been realized. Herein, we report a novel olefin dioxygenation catalyzed by cationic palladium diphosphine complexes. In comparison to related Pd-based methods, this olefin difunctionalization presumably occurs by a distinct Pd(II)/Pd(IV) mechanism and is significantly broad in scope, not limited to terminal olefins and/or alkenes bearing a directing group. Due to the low cost and toxicity of Pd salts relative to Os complexes, this strategy also represents a promising compliment to the well-known Sharpless dihydroxylation (Scheme 1).
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