Torben Rogge

Ruthenium(II)-catalysed remote C–H alkylations as a versatile platform to meta -decorated arenes

The full control of positional selectivity is of prime importance in C–H activation technology. Chelation assistance served as the stimulus for the development of a plethora of ortho-selective arene functionalizations. In sharp contrast, meta-selective C–H functionalizations continue to be scarce, with all ruthenium-catalysed transformations currently requiring difficult to remove or modify nitrogen-containing heterocycles. Herein, we describe a unifying concept to access a wealth of meta-decorated arenes by a unique arene ligand effect in proximity-induced ruthenium(II) C–H activation catalysis. The transformative nature of our strategy is mirrored by providing a step-economical entry to a range of meta-substituted arenes, including ketones, acids, amines and phenols—key structural motifs in crop protection, material sciences, medicinal chemistry and pharmaceutical industries.

Electrooxidative Ruthenium‐Catalyzed C−H/O−H Annulation by Weak O‐Coordination

Electrocatalysis has been identified as a powerful strategy for organometallic catalysis, and yet electrocatalytic C-H activation is restricted to strongly N-coordinating directing groups. The first example of electrocatalytic C-H activation by weak O-coordination is presented, in which a versatile ruthenium(II) carboxylate catalyst enables electrooxidative C-H/O-H functionalization for alkyne annulations in the absence of metal oxidants; thereby exploiting sustainable electricity as the sole oxidant. Mechanistic insights provide strong support for a facile organometallic C-H ruthenation and an effective electrochemical reoxidation of the key ruthenium(0) intermediate.

Distal Weak Coordination of Acetamides in Ruthenium(II)‐Catalyzed C−H Activation Processes

C-H activations with challenging arylacetamides were accomplished by versatile ruthenium(II) biscarboxylate catalysis. The distal C-H functionalization offers ample scope-including twofold oxidative C-H functionalizations and alkyne hydroarylations-through facile base-assisted internal electrophilic-type substitution (BIES) C-H ruthenation by weak O-coordination.

Arene‐Ligand‐Free Ruthenium(II/III) Manifold for meta‐C−H Alkylation: Remote Purine Diversification

meta-Selective C-H alkylations of bioactive purine derivatives were accomplished by versatile ruthenium catalysis. Thus, the arene-ligand-free complex [Ru(OAc)2 (PPh3 )2 ] enabled remote C-H functionalizations with ample scope and excellent levels of chemo- and positional selectivities. Detailed experimental and computational mechanistic studies provided strong support for a facile C-H activation within a ruthenium(II/III) manifold.

Mild Decarboxylative C−H Alkylation: Computational Insights for Solvent‐Robust Ruthenium(II) Domino Manifold

Computational studies on decarboxylative C-H alkenylations provided key insights into the solvent-robust nature of C-H activation/decarboxylation domino reactions. These properties were exploited for ruthenium(II)-catalyzed C-H alkylations by a decarboxylative process with ample scope under copper-free and silver-free reaction conditions.

Nickel-catalyzed reductive thiolation and selenylation of unactivated alkyl bromides

Chalcogen-containing compounds have received considerable attention because of their manifold applications in agrochemicals, pharmaceuticals, and material science. While many classical methods have been developed for preparing organic sulfides, most of them exploited the transition-metal-catalyzed cross-couplings of aryl halides or pseudo halides with thiols or disulfides, with harsh reaction conditions usually being required. Herein, we present a user-friendly, nickel-catalyzed reductive thiolation of unactivated primary and secondary alkyl bromides with thiosulfonates as reliable thiolation reagents, which are easily prepared and bench-stable. Furthermore, a series of selenides is also prepared in a similar fashion with selenosulfonates as selenolation reagents. This catalytic method offers a facile synthesis of a wide range of unsymmetrical alkyl-aryl or alkyl-alkyl sulfides and selenides under mild conditions with an excellent tolerance of functional groups. Likewise, the use of sensitive and stoichiometric organometallic reagents can be avoided.Chalcogen-containing compounds find broad application in chemical industry. Here, the authors report a nickel-catalyzed reductive chalcogenation of unactivated alkyl bromides with thiosulfonates and selenosulfonates to access a range of unsymmetrical sulfides and selenides under mild conditions.

Ruthenium(IV) Intermediates in C−H Activation/Annulation by Weak O-Coordination

Ruthenium(IV) complexes were identified as key intermediates of C-H/O-H activations by weak O-coordination. Thus, the annulations of sulfoxonium ylides by benzoic acids provided expedient access to diversely-decorated isocoumarins with ample scope. Detailed experimental and computational studies provided strong support for a facile BIES-C-H activation, along with cyclometalated ruthenium(IV) intermediates within a versatile ruthenium(II/IV) catalysis regime (BIES=base-assisted internal electrophilic substitution).