Convenient and versatile synthesis of formyl-substituted benzoxaboroles

Despite of the medicinal significance of benzoxaboroles, with the newly discovered clinical compound AN2690 as an example, the synthetic method for rapid diversification of this novel scaffold is lacking. To this end, a versatile and scalable synthesis of formyl-substituted benzoxaboroles is described here. A key step is the mono-oxidation of the two hydroxyls in compound 4 by taking advantage of the stable oxaborole ring in non-coordinating solvents, which was devised based on the study of the intramolecular coordination and exchange properties.