Direct Access to Benzolactams and Benzolactones via Nickel Catalyzed Carbonylation with CO.

A new nickel catalyzed cross-electrophile coupling for accessing γ-lactams (isoindolinones) as well as γ-lactones (isobenzofuranones) via carbonylation with CO is documented. The protocol exploits the synergistic role of redox-active Ni(II) complexes and AlCl as a CO activator/oxygen scavenger, leading to the formation of a wide range of cyclic amides and esters (28 examples) in good to high yields (up to 87 %). A dedicated computational investigation revealed the multiple roles played by AlCl.

Nickel Catalyzed Carbonylation/Carboxylation Sequence via Double CO Incorporation.

A carbonylation-carboxylation synthetic sequence, via double CO fixation, is described. The productive merger of a Ni-catalyzed cross-electrophile coupling manifold, with the use of AlCl, triggered a cascade reaction with the formation of three consecutive C-C bonds in a single operation. This strategy traces an unprecedented synthetic route to ketones under Lewis acid assisted carbon dioxide valorization.

Electrochemical C(sp)-H functionalization of ethers hydrogen-atom transfer by means of cathodic reduction.

The chemo- and stereoselective electrochemical allylation/alkylation of ethers is presented a C(sp)-H activation event. The electrosynthetic protocol enables the realization of a large library of functionalized ethers (35 examples) in high yields (up to 84%) cathodic activation of a new type of redox-active carbonate (RAC), capable of triggering HAT (Hydrogen-Atom-Transfer) events through the generation of electrophilic oxy radicals. The process displayed high functional group tolerance and mild reaction conditions.

Direct Synthesis of α-Aryl-α-Trifluoromethyl Alcohols via Nickel Catalyzed Cross-Electrophile Coupling.

A nickel-catalyzed reductive cross-electrophile coupling between the redox-active N-trifluoroethoxyphthalimide and iodoarenes is documented. The protocol reproduces a formal arylation of trifluoroacetaldehyde under mild conditions in high yields (up to 88 %) and with large functional group tolerance (30 examples). A combined computational and experimental investigation revealed a pivotal solvent assisted 1,2-Hydrogen Atom Transfer (HAT) process to generate a nucleophilic α-hydroxy-α-trifluoromethyl C-centered radical for the Csp -Csp bond forming process.

Enantioselective CO Fixation Via a Heck-Coupling/Carboxylation Cascade Catalyzed by Nickel.

A novel asymmetric nickel-based procedure has been developed in which CO fixation is achieved as a second step of a truncated Heck coupling. For this, a new chiral ligand has been prepared and shown to achieve enantiomeric excesses up to 99 %. The overall process efficiently furnishes chiral 2,3-dihydrobenzofuran-3-ylacetic acids, an important class of bioactive products, from easy to prepare starting materials.