Unanticipated Enhancement to Phosphide Nucleophilicity in Dimethyl Sulfoxide for Advanced Catalytic P-C Bond Formation Reactions

An exceptional nucleophilicity of phosphide (R2P-) was discovered for reactions conducted in dimethyl sulfoxide (DMSO) and leveraged for catalytic P-C bond formation. A range of simple bases affect this reactivity, and sodium hydroxide was chosen for deeper analysis due to its simplicity and abundance. This enhanced reactivity is not solely due to the high dielectric constant of DMSO or super base formation, rather aspects of phosphine association, proton management, and solubility drive the enhanced reactivity, based on comparison between solvents and spectroscopic analysis. The impact of this enhanced reactivity is substantial. Ring-opening reactions of epoxide and cyclopropane substrates are possible under catalytic conditions at ambient temperature. Likewise, hydrophosphination of a sweeping range of alkene and alkyne substrates is accessible at ambient temperature. To further demonstrate the utility of this simple, inexpensive, and water-tolerant catalysis, the catalytic preparation of phosphonium salts was also demonstrated. Despite tremendous advances in s-block catalysts, the hydroxide/DMSO combination provides the greatest combination of activation and versatility of any known P-C bond forming catalyst.