Palladium‐Catalyzed Divergent Arylation with Triazolopyridines: One‐Pot Synthesis of 6‐Aryl‐2‐α‐styrylpyridines

Abstract

We have developed a new strategy for palladium‐catalyzed arylation reactions with triazolopyridines, wherein two different chemical transformations (C‐3 vs. C‐7) are observed by differentiating the substrates using different bases. The reactive palladium carbenoids were directly generated from triazolopyridines and underwent denitrogenative arylations with aryl bromides. Intriguingly, when potassium carbonate was replaced with potassium tert‐butoxide, direct CH arylation occurred at the most acidic position (C‐7). Moreover, two different catalytic arylation events were successfully performed in a one‐pot sequence, providing a convenient access to 6‐aryl‐2‐α‐styrylpyridines.magnified image

Recent Advances in Denitrogenative Reactions of Pyridotriazoles

“…Hong and co-workers have reported an approach to 1aryl-1-(2-pyridyl)ethenes 79 via the Pd-catalyzed denitrogenative arylation of pyridotriazoles 78 (Scheme 23). 22 Among the Pd catalysts tested, (Cy 3 P) 2 PdCl 2 was found to be superior. The reaction proceeded in the presence of Ni(OAc) 2 as an additive and potassium carbonate as a base.…”

Denitrogenative Transformations of Pyridotriazoles and Related Compounds: Synthesis of N-Containing Heterocyclic Compounds and Beyond

“…The following reaction with acetic anhydride would generate the ylide intermediate 138 , which presumably via acyl group migration and reductive elimination of palladium catalyst produces 132 . Similar to Hong’s method described above, the pyridotriazole moiety plays a dual role both as a directing group for the C–H functionalization and as a carbene precursor. The Driver group also reported conversion of pyridotriazoles into picolyl alcohol derivatives under heating with HCl or AcOH …”

Metal‐Catalyzed Synthesis of 1,1‐Diarylethylene Scaffolds

“…In 2016, Hong and co‐workers reported a new strategy for the palladium‐catalyzed arylation of triazolopyridines . Their method was based on the ability of the triazole moiety of triazolopyridines to exist in their closed or open forms; in this way, the triazolopyridines may serve as precursors of pyridyl carbenes (Figure ).…”