Direct and Rapid Synthesis of Arylphosphines (PIII) by Oxalyl Chloride Promoted Reduction of Inorganic Phosphorus Salts [TBA][H2PO4] with Trichlorosilane and Palladium Catalysis

Abstract

Given the high demand for organophosphorus compounds (OPCs), developments of sustainable routes toward OPCs synthesis attract much attention. Numerous efforts are contributing to P4 transformations into P1 chemistry. Nevertheless, the existing methods necessitate energy-immense multisteps often utilize corrosive and dangerous reagents originating from P4/Pred allotropes, harmful intermediates, and chemical waste, impeding further exploration and practical applications. Herein, direct and efficient transformation of inorganic phosphates [TBA][H2PO4] into OPCs is demonstrated. These salts were activated by cost-efficient oxalyl chloride at 20°C in 5 minutes, through a double chlorination of OH on phosphorus upon elimination of CO2 and CO molecules, followed by reducing the resultant intermediate with trichlorosilane, then coupling with haloaryls under palladium-catalysis to provide desired OPCs. Diverse OPCs with tolerance of various functionalities on aryl halides achieved with potential scale-up and industrial applications, eliminating the reliance on extortionate, problematic P4 allotropes. X-ray diffraction and DFT calculations revealed activated intermediate [TBA][PO2Cl2].