Iron-Catalyzed C(sp)-C(sp) Coupling to Construct Quaternary Carbon Centers.

The construction of quaternary carbon centers via C-C coupling protocols remains challenging. The coupling of tertiary C(sp) with secondary or tertiary C(sp) counterparts has been hindered by pronounced steric clashes and many side reactions. Herein, we have successfully developed a type of bisphosphine ligand iron complex-catalyzed coupling reactions of tertiary alkyl halides with secondary alkyl zinc reagents and efficiently realized the coupling reaction between tertiary C(sp) and secondary C(sp) with high selectivity for the initial instance, which provided an efficient method for the construction of quaternary carbon centers with high steric hindrance. The combination of an iron catalyst and directing group of the substrate makes the great challenging transformation possible.