A flow-metallaelectro-catalyzed C–H activation was realized in terms of robust rhodaelectro-catalyzed alkyne annulations. To this end, a modular electro-flow cell with a porous graphite felt anode was designed to ensure efficient turnover. Thereby, a variety of C–H/N–H functionalizations proved amenable for alkyne annulations with high levels of regioselectivity and functional group tolerance, viable in both an inter- or intramolecular manner. The electro-flow C–H activation allowed easy scale up, while in-operando kinetic analysis was accomplished by online flow-NMR spectroscopy. Mechanistic studies suggest an oxidatively induced reductive elimination pathway on rhodium­(III) in an electrocatalytic regime.

Significant progress has been observed in recent years in the synthesis of allylic amines, which are important building blocks in synthetic chemistry. Most of these processes are effective toward the preparation of allylic amines, with limited potential to introduce three or four different substituents on the olefinic unit in a stereocontrolled fashion. Therefore, the discovery of a mild and operationally simple protocol allowing such challenging stereoselective synthesis of multisubstituted allylic amines remains an inspiring target. Herein, we report the first general and practical methodology for the stereoselective synthesis of tri- and tetrasubstituted allylic amines based on Pd-catalyzed conversion of allyl surrogates readily obtained from cyclic vinyl carbonates. These rare conversions are characterized by excellent stereoselectivity, operational simplicity, mild reaction conditions, and wide scope in reaction partners. DFT studies were performed to rationalize the stereocontrol in these allylic amine formation reactions, and evidence is provided that the formation of a six-membered palladacyclic intermediate leads toward the formation of (Z)-configured allylic amine products.

Detailed density functional theory calculations provide valuable insight into reactivity-controlling factors in transition metal-catalyzed C−H activation by carboxylate assistance. The chelation-assisted activation of a variety of arenes by 3d and 4d transition metal complexes was analyzed by means of bond order analysis through density functional theory (DFT) calculations as well as energy decomposition analysis through DLPNO−CCSD(T) calculations, thereby providing in-depth information on distinct electronic influences on the key C−H activation transition state and demonstrating a preferred activation through a base-assisted internal electrophilic substitution (BIES) rather than a concerted metalationdeprotonation (CMD) pathway.

An efficient protocol was developed to construct functionally dense quaternary carbons with concomitant formation of a new Csp-Csp bond via Pd-catalyzed decarboxylative transformation of vinyl cyclic carbonates. This redox-neutral catalytic system features stereocontrolled formation of multisubstituted allylic scaffolds with an aldehyde functionality generated in situ, and it typically can be performed at room temperature without any additives. DFT calculations provide a rationale toward the selective formation of these compounds and reveal a complex mechanism that with the help of microkinetic models is able to reproduce the nontrivial dependence of the identity of the product on the nature of the substituents in the substrate.

A ruthenium‐catalyzed electrochemical dehydrogenative annulation reaction of imidazoles with alkynes has been established, enabling the preparation of various bridgehead N‐fused [5,6]‐bicyclic heteroarenes through regioselective electrochemical C−H/N−H annulation without chemical metal oxidants. Novel azaruthenabicyclo[3.2.0]heptadienes were fully characterized and identified as key intermediates. Mechanistic studies are suggestive of an oxidatively induced reductive elimination pathway within a ruthenium(II/III) regime.