Synthesis of imidoyltrialkylphosphonium salts through photocatalytic reactions between isocyanides and tri- <i>t</i> -butylphosphine

Abstract Isocyanides and tri-t-butylphosphine undergo a C–P bond-forming reaction under photocatalytic conditions. The resulting imidoyltrialkylphosphonium salts represent a new class of organophosphorus compounds that can be isolated by silica gel chromatography under air. This transformation exhibits broad functional group tolerance and affords a range of imidoylphosphonium salts in good to moderate yields. Mechanistic studies suggest a reaction pathway involving addition of a phosphine radical cation to the isocyanide, followed by single-electron reduction to form a phosphorus ylide intermediate. Furthermore, the imidoylphosphonium salts exhibit unique reactivity under reductive conditions, enabling their conversion to imidoylphosphines through elimination of a P-substituent.