Transition-metal-free, one-pot synthesis of Benzoxaboroles from o-bromobenzaldehydes via visible-light-promoted borylation

A novel and simple one-pot stepwise method to synthesize benzoxaboroles was demonstrated. This step-by-step synthetic method includes photocatalytic boronization with phenothiazine as photocatalyst and sequencely water-induced reduction in the presence of bis(pinacolato)diboron. A series of o-bromobenzaldehydes were well tolerated in the standard conditions. In addition, this method has been successfully applied in the synthesis of anti-tuberculosis candidate drug GSK 3036656 and anti-fungal drug Tavaborole.