Tatsuhiko Yoshino

Active without activation: In an inexpensive and atom-economical approach to CH bond functionalization, a cationic CoIII complex (see scheme) was used to generate nucleophilic organometallic species in situ without additional activating reagents. Under these conditions, aryl CH bonds underwent efficient addition to polar electrophiles, including α,β-unsaturated N-acyl pyrroles as β-substituted ester and amide surrogates.

Abstract High‐valent (pentamethylcyclopentadienyl)cobalt(III) [Cp*Co(III)] catalysts were found as inexpensive alternatives to (pentamethylcyclopentadienyl)rhodium(III) [Cp*Rh(III)] catalysts in the field of C—H bond functionalization, and applied to a variety of transformations. In this review, after the discovery and early examples of Cp*Co(III)‐catalyzed C—H bond functionalization are summarized, the unique reactivity and selectivity of Cp*Co(III) and the differences between the cobalt and rh

Recent advances in Cp^x M^III catalysis (M=Co, Rh, Ir) have enabled a variety of enantioselective C(sp² )-H functionalization reactions, but enantioselective C(sp³ )-H functionalization is still largely unexplored. We describe an asymmetric C(sp³ )-H amidation of thioamides using an achiral Co^III /chiral carboxylic acid hybrid catalytic system, which provides easy and straightforward access to chiral β-amino thiocarbonyl and β-amino

Transition-metal-catalyzed C-H functionalization reactions with Cp*M^III catalysts (M=Co, Rh, Ir) have found a wide variety of applications in organic synthesis. Albeit the intrinsic difficulties in achieving catalytic stereocontrol using these catalysts due to their lack of additional coordination sites for external chiral ligands and the conformational flexibility of the Cp ligand, catalytic enantioselective C-H functionalization reactions using the Group 9 metal triad with Cp-type l

Overriding innate reactivity: The utility of a CoIII catalyst to promote the C2-selective addition of indoles to imines was demonstrated. The CoIII catalyst completely changed the regioselectivity in comparison with simple Lewis acid catalyzed Friedel–Crafts C3-selective addition. High turnover number (TON) of the catalyst, up to 1.8×102 (with s/c=200; see scheme; s/c is the substrate/catalyst ratio), was achieved. As a service to our authors and readers, this journal provides supporting informa

Aktiv ohne Aktivierung: In einem preiswerten und atomökonomischen Ansatz der C-H-Funktionalisierung wird ein kationischer Cobalt(III)-Komplex verwendet, um nucleophile metallorganische Spezies in situ ohne Zusatz aktivierender Reagentien herzustellen (siehe Schema). Aryl-C-H-Bindungen addieren effizient an polare Elektrophile, einschließlich α,β-ungesättigter N-Acylpyrrole als β-substituierte Ester- und Amid-Surrogate.

Enantioselective C–H functionalization is a powerful tool for synthesizing chiral molecules. In the past few years, the combination of high-valent group 9 metals with achiral Cpx ligands and chiral carboxylic acids (CCA) has emerged as a promising catalytic system to enable selective cleavage and functionalization of enantiotopic C–H bonds. This Perspective summarizes the background, catalyst design, and applied reactions in detail, followed by a discussion of future directions.

Construction of contiguous tetrasubstituted chiral carbon stereocenters via direct catalytic asymmetric aldol reaction of alpha-substituted alpha-isothiocyanato esters with unactivated simple ketones is described. A Bu(2)Mg/Schiff base catalyst promoted the aldol addition/cyclization sequence at room temperature, giving protected alpha-amino-beta-hydroxy esters with contiguous tetrasubstituted chiral carbon stereocenters in 99 to 68% yield, 98:2 to 74:26 dr, and 98 to 82% ee.

Catalytic enantioselective directed methylene C(sp³ )-H amidation reactions of 8-alkylquinolines using a Cp*Rh^III /chiral carboxylic acid (CCA) hybrid catalytic system are described. A binaphthyl-based chiral carboxylic acid efficiently differentiates between the enantiotopic methylene C-H bonds, which leads to the formation of C-N bonds with good enantioselectivity.

Enantioselective C-H functionalization reactions using trivalent group 9 metals (Co, Rh, Ir) have been investigated mainly on the basis of the development of well-designed chiral cyclopentadienyl (Cp) ligands. Although it has recently been demonstrated that chiral carboxylic acids combined with achiral Cp-type ligands can enable highly enantioselective C-H functionalization reactions, the structural diversity of the applied chiral acids remains limited. Here, we report that chiral 2-aryl ferroce

A highly atom economical and stereoselective synthesis of tetrasubstituted α,β-unsaturated amides was achieved by a Cp*Co^III -catalyzed C-H alkenylation/directing group migration sequence. A carbamoyl directing group, which is typically removed after C-H functionalization, worked as an internal acylating agent and migrated onto the alkene moiety of the product. The directing group migration was realized with the Cp*Co^III catalyst, while a related Cp*Rh^III catalys

Abstract C−H functionalization reactions hold great potential for the streamlined synthesis of complex molecules and are currently a “hot” topic in organic synthesis. Among the various transition metals that have been used, cobalt has recently attracted increased attention as a catalyst for C−H functionalization reactions, owing to its ready availability and high reactivity. Although a number of cobalt‐catalyzed C(sp 2 )−H functionalization reactions have been reported to date, C(sp 3 )−H functi

Abstract We report enantioselective 1,4‐addition reactions of indoles to maleimides via a C2‐selective C−H activation catalyzed by an achiral Cp*Co III /chiral carboxylic acid system. In these reactions, a BINOL‐derived chiral carboxylic acid enables the enantioselective reactions as the sole chiral source.

Abstract Recent advances in Cp x M III catalysis (M=Co, Rh, Ir) have enabled a variety of enantioselective C(sp 2 )−H functionalization reactions, but enantioselective C(sp 3 )−H functionalization is still largely unexplored. We describe an asymmetric C(sp 3 )−H amidation of thioamides using an achiral Co III /chiral carboxylic acid hybrid catalytic system, which provides easy and straightforward access to chiral β‐amino thiocarbonyl and β‐amino carbonyl building blocks with a quaternary carbon