Catalyst-Free Visible Light Mediated Synthesis of Unsymmetrical Tertiary Arylphosphines

Arylation of tertiary aryl and alkyl phosphines bearing 2-cyanoethyl group with aryl(mesityl)iodonium triflates under blue light irradiation followed by retro-Michael reaction of the in situ generated quaternary phosphonium salts initiated by DBU represent a novel efficient and general method for the preparation of distinctly substituted tertiary arylphosphines. An operationally simple, one-pot protocol features mild, transition-metal-free conditions, high selectivity, broad functional group compatibility, as well as scalability and would be applied to substrates with different electronic and steric nature.