Ni-Catalyzed Regioselective 1,2-Dicarbofunctionalization of Olefins by Intercepting Heck Intermediates as Imine-Stabilized Transient Metallacycles

We disclose a strategy
for Ni-catalyzed dicarbofunctionalization
of olefins in styrenes by intercepting Heck C­(sp3)–NiX
intermediates with arylzinc reagents. This approach utilizes a readily
removable imine as a coordinating group that plays a dual role of
intercepting oxidative addition species derived from aryl halides
and triflates to promote Heck carbometalation and stabilizing the
Heck C­(sp3)–NiX intermediates as transient metallacycles
to suppress β-hydride elimination and facilitate transmetalation/reductive
elimination steps. This method affords diversely substituted 1,1,2-triarylethyl
products that occur as structural motifs in various natural products.