Ni‐Catalyzed Chelation‐AssistedDirect Functionalization of Inert C—H Bonds

Abstract

During the last two decades, impressive advancements have been achieved in transition metal-catalyzed chelation-assisted C-H functionalization reaction. While reactions in this field are still dominated by precious 4d or 5d metals (e.g., Pd, Rh, Ir), the 3d base metals (e.g., Ni, Co, Cu, Fe) have made significant headway partially due to their relatively large abundance, low cost, low toxicity as well as their occasionally occurred novel reactivity when compared to their noble cousins. This review will give a comprehensive summary on Ni-catalyzed functionalization of inert C-H bonds assisted by chelation groups. For clarity, the content is classified by the newly formed chemical bonds, namely C-C, C-N, C-chalcogen and C-halogen bond formation.Yan-Hua Liu (left) received his B.S. degree in 2013 from North University of China. Then he pursued his Ph.D. degree under the supervision of Prof. Bing-Feng Shi in organic chemistry at Zhejiang University. His current research is focused on transition-metal-catalyzed enantioselective C-H bond activation.

Electrosynthesis of Azobenzenes Directly from Nitrobenzenes

“… a Reaction conditions: anode: graphite rod (6 mm) and cathode: Pt foil (1.0 x 1.0 cm 2 ), constant current = 20 mA, 1a (0.5 mmol), NH 4 Cl (1.5 mmol), DMSO (8 mL) in an undivided cell, rt, air, 5 h. b Isolated yield based on 1a . …”

“…[ 1 ] Recently, due to the strong coordination ability of nitrogen atom, many chemists utilized the azo group as a directing group for ortho C—H functionalization. [ 2 ] Accordingly, all sorts of preparation methods for the synthesis of these compounds have been developed. The traditional synthetic method is primarily based on coupling of aryl diazonium salts with nucleophiles.…”

Radical Mechanism of Ir III /Ni II -Metallaphotoredox-Catalyzed C(sp 3 )–H Functionalization Triggered by Proton-Coupled Electron Transfer: Theoretical Insight

“…4 Over the past decades, activation of C−H bonds with a wide variety of directing groups has become an economically attractive synthetic strategy, which plays an important role in determining the proximal C-H reactivity. [5][6] And transition-metal catalysts, by Pd [7][8][9] , Rh [10][11] , Ru [12][13] , Ir [14][15] and Ni [16][17][18] complexes, are crucial for the functionalization of C−H bonds as a versatile and an efficient strategy to construct the C−C and C−X bonds in organic synthesis. [19][20][21] These reactions have been realized using the directing groups strategy, [22][23] radical addition, 24 the concerted 6 advantageous approach.…”

Copper-catalyzed monoselective C–H amination of ferrocenes with alkylamines

“…Thus far, the transition-metal-catalyzed C–H functionalization strategy has innovated the way to producing ferrocene derivatives [ 13 – 16 ]. Especially, the 3d transition metals, such as Cu, Co and Ni, have been exploited to convert C–H bonds to various functional groups, attributing to the cost-effective and less toxic properties, which render C–H transformations both economically desirable and environmentally benign ( Scheme 1a ) [ 17 – 22 ]. Early in 2015, the Ackermann group reported the first example of a low-valent Co-catalyzed C–H alkenylation of 2-pyridinylferrocene [ 23 ].…”

“…Especially, the 3d transition metals, such as Cu, Co and Ni, have been exploited to convert C-H bonds to various functional groups, attributing to the cost-effective and Scheme 1: 3d-Transition-metal-catalyzed C-H functionalization to access functionalized ferrocenes. less toxic properties, which render C-H transformations both economically desirable and environmentally benign (Scheme 1a) [17][18][19][20][21][22]. Early in 2015, the Ackermann group reported the first example of a low-valent Co-catalyzed C-H alkenylation of 2-pyridinylferrocene [23].…”