Synthesis of dibenzo[c,e]oxepin-5(7H)-ones from benzyl thioethers and carboxylic acids: rhodium-catalyzed double C-H activation controlled by different directing groups.

A rhodium(III)-catalyzed cross-coupling of benzyl thioethers and aryl carboxylic acids through the two directing groups is reported. Useful structures with diverse substituents were efficiently synthesized in one step with the cleavage of four bonds (CH, CS, OH) and the formation of two bonds (CC, CO). The formed structure is the privileged core in natural products and bioactive molecules. This work highlights the power of using two different directing groups to enhance the selectivity of a double CH activation, the first of such examples in cross-oxidative coupling.