Pd-Catalyzed 1,3-Alkenylarylation of Skipped Diene via Metal Migration.

We disclose a palladium-catalyzed difunctionalization of skipped diene with alkenyl triflates and arylboronic acids to produce 1,3-alkenylarylated products. The reaction proceeded efficiently with Pd(acac)2 as a catalyst and CsF as a base for a wide range of electron-deficient and electron-rich arylboronic acids as well as oxygen-heterocyclic, sterically hindered, and complex natural product-derived alkenyl triflates bearing various functional groups. The reaction produced 3-aryl-5-alkenylcyclohexene derivatives with 1,3-syn-disubstituted stereochemistry.

Ni-Catalyzed Regio- and Stereoselective Alkylarylation of Unactivated Alkenes in γ,δ-Alkenylketimines.

We disclose a Ni-catalyzed vicinal alkylarylation of unactivated alkenes in γ,δ-alkenylketimines with aryl halides and alkylzinc reagents. The reaction produces γ-C(sp3)-branched δ-arylketones with the construction of two new C(sp3)-C(sp3) and C(sp3)-C(sp2) bonds. Electron-deficient alkenes play crucial dual roles as ligands to stabilize reaction intermediates and to increase catalytic rates for the formation of C(sp3)-C(sp3) bonds. This alkene alkylarylation reaction is also effective for secondary alkylzinc reagents and internal alkenes, and proceeds with a complete regio- and stereocontrol, affording products with up to three contiguous all-carbon all-cis secondary stereocenters.

Ni(I)-Catalyzed ß,δ-Vinylarylation of γ,δ-Alkenyl α-Cyanocarboxylic Esters via Contraction of Transient Nickellacycles.

We disclose a transmetalation-initiated Ni(I)-catalyzed regioselective ß,δ-vinylarylation of γ,δ-alkenyl α-cyanocarboxylic esters with vinyl triflates and arylzinc reagents. This reaction proceeds via contraction of six-membered nickellacycles to five-membered nickellacycles to form carbon-carbon bonds at the nonclassical homovicinal sites, and it provides expeditious access to a wide range of complex aliphatic α-cyanoesters, α-cyanocarboxylic acids, dicarboxylic acids, dicarboxylic acid monoamides, monocarboxylic acids, nitriles, and spirolactones. Control, deuterium labeling, and crossover experiments indicate that (i) the nickellacycle contraction occurs by ß-H elimination, followed by hydronickellation on transiently formed alkenes, and (ii) the Ni species are stabilized as Ni-enolates.