Photocatalyzed Synthesis of Unsymmetrical Alkylphosphorus(V) Compounds Using Imidazolium Phosphonites.

Here, we report a synthetic approach for a wide range of unsymmetrical alkylphosphorus(V) compounds, alkyl-P(O)XY (X ≠ Y) using imidazolium phosphonites as bifunctional reagents. This protocol consists of two sequences, C(sp3)─P bond formation via an organic photoredox-catalyzed decarboxylative alkylation of imidazolium phosphonites with aliphatic carboxylic acid derivatives and P─X (X═O, N, F, and S) bond formation via the SNP(V) reaction. In this process, the imidazolium group facilitates 1) radical addition to the phosphonite reagent by stabilizing the resulting phosphoranyl radical intermediate and 2) the SNP(V) reaction as a good leaving group. This protocol allows the introduction of primary, secondary and tertiary alkyl substituents and various heteroatom substituents onto P(V) scaffolds.