1,3-Diphenyldisiloxane Enables Additive-Free Redox Recycling Reactions and Catalysis with Triphenylphosphine

Abstract

The recently reported chemoselective reduction of phosphine oxides with 1,3-diphenyldisiloxane (DPDS) has opened up the possibility of additive-free phosphine oxide reductions in catalytic systems. Herein we disclose the use of this new reducing agent as an enabler of phosphorus redox recycling in Wittig, Staudinger, and alcohol substitution reactions. DPDS was successfully utilized in ambient-temperature additive-free redox recycling variants of the Wittig olefination, Appel halogenation, and Staudinger reduction. Triphenylphosphine-promoted catalytic recycling reactions were also facilitated by DPDS. Additive-free triphenylphosphine-promoted catalytic Staudinger reductions could even be performed at ambient temperature due to the rapid nature of phosphinimine reduction, for which we characterized kinetic and thermodynamic parameters. These results demonstrate the utility of DPDS as an excellent reducing agent for the development of phosphorus redox recycling reactions.

Cobalt- or rhodium-catalyzed synthesis of 1,2-dihydrophosphete oxides via C–H activation and formal phosphoryl migration

“…1). 3 For instance, compound I is known as a new organic catalyst that enables the reductive C–N cross-coupling of functionalized nitroalkanes with arylboronic acids, and compound II exhibits unique photophysical properties, while compound III is employed as a useful chiral bidentate ligand. However, efficient methods to access four-membered phosphacycles, especially 1,2-dihydrophosphete (oxides), only remain sporadic.…”