Phosphonylation of alkyl radicals

Alkylphosphonates have found widespread applications in pharmaceuticals, agrochemicals, and materials science, and their synthesis is of paramount importance in organic chemistry. While nucleophilic and electrophilic C(sp3)-phosphonylation are well documented, the phosphonylation of alkyl radicals remains elusive. Herein, we report the decarboxylative radical phosphonylation with trialkyl phosphites. Thus with the co-catalysis of 4DPAIPN (1,2,3,5-tetrakis(diphenylamino)-4,6-dicyanobenzene) and Cu(OAc)2, the visible light-induced reaction of redox-active esters of aliphatic carboxylic acids with trialkyl phosphites at room temperature provides the corresponding alkylphosphonates in satisfactory yields. The protocol exhibits broad substrate scope and wide functional group compatibility, enabling the late-stage modification of complex molecules. A mechanism involving the copper-assisted coupling of alkyl radicals with P(OR)3 followed by Arbuzov-type dealkylation of the resulting phosphonium intermediates is proposed.