Rhodium(III)-Catalyzed Oxidative Annulation of 2,2'-Bipyridine N-Oxides with Alkynes via Dual C-H Bond Activation.

Rh(III)-catalyzed switchable annulation of 2,2'-bipyridine N-oxides with internal alkynes via dual C-H bond activation has been developed. Tuning the reaction conditions enabled the reaction pathway to be switched between rollover and nonrollover annulation, delivering 5,6-disubstituted-1,10-phenanthrolines and 5,6,7,8-tetrasubstituted-1-(pyridin-2-yl)isoquinoline 2-oxides in high yields, respectively. The procedures feature excellent regioselectivity, broad substrate scope, and high tolerance of functional groups. The synthetic utilities of these obtained products were demonstrated in the catalytic reactions.