Facile Rh(III)-Catalyzed Synthesis of Fluorinated Pyridines.

A Rh(III)-catalyzed C-H functionalization approach was developed for the preparation of multisubstituted 3-fluoropyridines from α-fluoro-α,β-unsaturated oximes and alkynes. Oximes substituted with aryl, heteroaryl, and alkyl β-substituents were effective coupling partners, as were symmetrical and unsymmetrical alkynes with aryl and alkyl substituents. The first examples of coupling α,β-unsaturated oximes with terminal alkynes was also demonstrated and proceeded with uniformly high regioselectivity to provide single 3-fluoropyridine regioisomers. Reactions were also conveniently set up in air on the benchtop.