Modular Synthesis of Halogenated Xanthones by a Divergent Coupling Strategy.

A versatile strategy to halogenated xanthones was developed that relies on a modular coupling of vanillin derivatives with a dibromoquinone. Depending on the reaction conditions, either the 6- or the 7-bromo heterocycles may be obtained in a divergent manner. These heterocycles may be readily further elaborated by sequential Sonogashira couplings, and the sequence may be successfully applied to substructures of the antibiotic lysolipin.