Rh III -Catalyzed C-H N -Heteroarylation and Esterification Cascade of Carboxylic Acid with Organoboron Reagents and 1,2-Dichloroethane in One-Pot Synthesis.

A Rh III -catalyzed C(sp 2 )-H N -heteroarylation and esterification cascade of aryl carboxylic acids with N -heteroaromatic boronates and 1,2-dichloroethane in a one-pot synthesis has been disclosed. The strong coordinating ability of ortho - and meta -substituted pyridine boronates and pyrazoles as well as unsubstituted pyrimidine allows them to serve as the coupling partners. This protocol allows late-stage modification of the key precursor of roflumilast and compounds of pharmaceutical interest, which highlights the potential application of this synthetic method.