Highly Effective Conditions for Nickel-Mediated Heck Cyclization Cascades Starting from Aryl and Vinyl Triflates

In contrast to the tremendous power of Pd-based Mizoroki–Heck reactions, methods to achieve such processes with other metals, particularly Ni, are generally lacking. Herein, we delineate specific conditions that can enable cascade variants of these C–C bond forming events to proceed smoothly under Ni catalysis. Critically, these reactions work with equal facility as their Pd-initiated counterparts when conducted intramolecularly, and in many cases are devoid of any Ni–H-mediated alkene isomerization within the starting materials and/or products as has typically been observed with previous Ni-based protocols. When conducted intermolecularly, the developed variant affords unique regioselectivity in product formation, substantively favoring 6-endo additions over the more standard 5-exo counterparts observed under Pd-based conditions. Finally, applications of the developed procedures to two different natural product syntheses are described