Rhodium(III)-Catalyzed Direct Coupling of Quinoline-8-Carbaldehydes with (Het)Arylboronic Acids for the Synthesis of 8-Aryloylquinolines.

Herein, we describe a method for the synthesis of aryl (het)aryl ketones by Rh(III)-catalyzed direct coupling reactions between chelating aldehydes and (het)arylboronic acids. The method has a broad substrate scope and a high functional group tolerance, and it uses commercially available starting materials. Scale-up of the reaction and subsequence synthesis of tubulin polymerization inhibitors demonstrated the utility of the method. A plausible mechanism is proposed on the basis of the fact that a stable cycloacylrhodium intermediate complex could be used as a catalyst and that this complex reacted stoichiomet-rically with the (het)arylboronic acid.