C–H activation has surfaced as an increasingly powerful tool for molecular sciences, with notable applications to material sciences, crop protection, drug discovery, and pharmaceutical industries, among others. Despite major advances, the vast majority of these C–H functionalizations required precious 4d or 5d transition metal catalysts. Given the cost-effective and sustainable nature of earth-abundant first row transition metals, the development of less toxic, inexpensive 3d metal catalysts for C–H activation has gained considerable recent momentum as a significantly more environmentally-benign and economically-attractive alternative. Herein, we provide a comprehensive overview on first row transition metal catalysts for C–H activation until summer 2018.

3d Transition Metals for C-H Activation.

Recent Advances in Hydrometallation of Alkenes and Alkynes via the First Row Transition Metal Catalysis

Molecular syntheses largely rely on time- and labour-intensive prefunctionalization strategies. In contrast, C-H activation represents an increasingly powerful approach that avoids lengthy syntheses of prefunctionalized substrates, with great potential for drug discovery, the pharmaceutical industry, material sciences, and crop protection, among others. The enantioselective functionalization of omnipresent C-H bonds has emerged as a transformative tool for the step- and atom-economical generation of chiral molecular complexity. However, this rapidly growing research area remains dominated by noble transition metals, prominently featuring toxic palladium, iridium and rhodium catalysts. Indeed, despite significant achievements, the use of inexpensive and sustainable 3d metals in asymmetric C-H activations is still clearly in its infancy. Herein, we discuss the remarkable recent progress in enantioselective transformations via organometallic C-H activation by 3d base metals up to April 2019.

Enantioselective C-H Activation with Earth-Abundant 3d Transition Metals.

Recent advances in the sulfonylation of C-H bonds with the insertion of sulfur dioxide.

Direct catalytic modifications of carbon–hydrogen (C H) bonds, ubiquitous in organic molecules, represent a powerful strategy in organic synthesis. In the past decade, chemists have focused on the development of sustainable methods for functionalization of inert C H bonds using cost-effective earth-abundant 3d transition-metal catalysts. To fully harness the potential of this technology, however, it is essential to control the stereoselectivity of the C H functionalization processes. This review describes developments in the emerging area of enantioselective functionalization of C H bonds by 3d transition-metal catalysts proceeding via inner-sphere C H activation.

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Enantioselective C-H Bond Functionalizations by 3d Transition-Metal Catalysts

A Ni–Al bimetallic catalyzed enantioselective C–H exo-selective cyclization of imidazoles with alkenes has been developed. A series of bi- or polycyclic imidazoles with β-stereocenter were obtained in up to 98% yield and >99% ee. The bifunctional SPO ligand-promoted bimetallic catalysis proved to be critical to this challenging stereocontrol.

Enantioselective Ni-Al Bimetallic Catalyzed exo-Selective C-H Cyclization of Imidazoles with Alkenes.

Twofold C-H annulation of readily available formamides and alkynes without built-in chelating groups was achieved. Ni-Al bimetallic catalysis enabled by a bulky BINOL-derived chiral secondary phosphine oxide (SPO) ligand proved to be critical for high reactivity and high selectivity. This reaction uses readily available formamides as starting materials and provides a concise synthetic pathway to a broad range of chiral ferrocenes in 40-98 % yield and 93-99 % ee.

Enantioselective Twofold C−H Annulation of Formamides and Alkynes without Built‐in Chelating Groups

A redox-neutral Ni-catalyzed intramolecular hydroarylation of alkene with simple arene has been developed, in which DMF played a proton shuttle role in facilitating the intramolecular coupling, avoiding the use of additional reductants and oxidants. A series of oxindoles with a quaternary center were obtained in up to 99% yield.

DMF-Promoted Redox-Neutral Ni-Catalyzed Intramolecular Hydroarylation of Alkene with Simple Arene

Allylic amines are versatile building blocks in organic synthesis and exist in bioactive compounds, but their synthesis via hydroaminoalkylation of alkynes with amines has been a formidable challenge. Here, we report a late transition metal Ni-catalyzed hydroaminoalkylation of alkynes with N-sulfonyl amines, providing a series of allylic amines in up to 94% yield. Double ligands of N-heterocyclic carbene (IPr) and tricyclohexylphosphine (PCy3) effectively promote the reaction.

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Ni-catalyzed hydroaminoalkylation of alkynes with amines

Dienols are important structural motifs in organic molecules, but most of the traditional synthetic methods required multistep prefunctionalization of substrates, leading to stoichiometric waste an...

https://www.chinesechemsoc.org/doi/pdf/10.31635/ccschem.020.202000235

Hao Chen

Papers

Enantioselective Ni-Al Bimetallic Catalyzed exo-Selective C-H Cyclization of Imidazoles with Alkenes.

Enantioselective Twofold C−H Annulation of Formamides and Alkynes without Built‐in Chelating Groups

DMF-Promoted Redox-Neutral Ni-Catalyzed Intramolecular Hydroarylation of Alkene with Simple Arene

Ni-catalyzed hydroaminoalkylation of alkynes with amines

Nickel- and Brønsted Acid-Catalyzed Redox-Neutral Coupling of 1,3-Dienes and Aldehydes for Synthesis of Dienols