Catalytic aerobic photooxidation of triarylphosphines using dibenzo-fused 1,4-azaborines

Although dibenzo-fused 1,4-heteroaromatics are utilized as strongly reducing photocatalysts in organic synthesis and polymerization, they have rarely been employed in catalytic photooxidation. Moreover, to date, their boron-analogs, dibenzo-fused 1,4-azaborines (DBABs), have not been applied in photocatalysis despite their promising potential as photocatalysts. Accordingly, herein, aerobic photooxidation of triarylphosphines (Ar3P) was performed using DBABs as photocatalysts. The reaction smoothly proceeded in an aprotic solvent, and phosphine oxides were obtained in appropriate yields. Density functional theory calculations suggested that DBAB captured and activated phosphadioxirane intermediates, which were generated by the interaction of Ar3P with O-1(2), at the Lewis acidic boron center.

Automated summary

In this study, DBAB was used as a photocatalyst for the aerobic photooxidation of triarylphosphines, leading to the formation of phosphine oxides in moderate yields. The results highlight the potential application of DBAB in photocatalysis.