Photocatalytic [3 + 2]-annulation sodium tetraarylborate: a fundamental approach for synthesizing 1,4,2-diazaborole analogs.

Substantial advancements have been achieved in the field of photocatalytic borylation utilizing 4c-7e Lewis base-boryl radicals. However, the utilization of 3c-5e neutral boryl radicals for C-B bond formation remains relatively underexplored due to their inherent instability. In this study, we successfully demonstrated the direct construction of C-B bonds using sodium tetraarylborate as a key reagent.