Palladium-Catalyzed Difunctionalization of Norbornenes via Arylation and Alkynylation

We report the first general and practical method for the addition of aryl halides and alkynes to norbornenes with palladium catalysis. Norbornenes have been used as the unsaturated acceptors of aryl and alkynyl groups to construct saturated bridged C-C bonds. The combination of Pd(OAc)(2)/PCy3HBF4 has been identified as the optimal system promoting difunctionalization of norbornenes via the C-X/C-H bond cleavage and highly selective C(sp(3))-C(sp(2))/C(sp(3))-C(sp) bond formation. Broad substrate scope and excellent functional group tolerance have been achieved to show the high efficiency of this approach. Mechanism studies based on experiments and DFT have been performed to gain insights into the catalytic mechanism.

Automated summary

This study presents a general and practical method for the addition of aryl halides and alkynes to norbornenes using palladium catalysis. Norbornenes function as unsaturated acceptors for aryl and alkynyl groups, leading to the formation of saturated bridged C-C bonds. The optimized Pd(OAc)(2)/PCy3HBF4 system enables the difunctionalization of norbornenes by cleavage of C-X/C-H bonds and highly selective formation of C(sp(3))-C(sp(2))/C(sp(3))-C(sp) bonds. Broad substrate scope and excellent functional group tolerance highlight the high efficiency of this approach. Mechanistic insights were gained through experimental and DFT-based studies.