Enantioselective C−H Activation with Earth‐Abundant 3d Transition Metals

Loup, Joachim; Dhawa, Uttam; Pesciaioli, Fabio; Wencel‐Delord, Joanna; Ackermann, Lutz

doi:10.1002/anie.201904214

Cited by 343 publications

(102 citation statements)

References 180 publications

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“…Finally, considering the accomplishments nickel catalysts have already achieved in traditional cross-coupling reactions (e.g., asymmetric catalysis) as well as recent advances in Pd-catalyzed C-H activation, further promising advances are expected in this fast-growing field, including the use of traceless/transient DG strategy, remote C-H activation, and asymmetric C-H activation. [101]…”

Section: Discussionmentioning

confidence: 99%

Ni‐Catalyzed Chelation‐Assisted Direct Functionalization of Inert C—H Bonds

2020

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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.

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Section: Discussionmentioning

confidence: 99%

Ni‐Catalyzed Chelation‐Assisted Direct Functionalization of Inert C—H Bonds

2020

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“…Albeit the wide applicability and selectivity demonstrated by these metals, their high cost and rather high toxicity constitute a limitation in the development of valuable alternatives to the classic metal-catalyzed cross-couplings [11]. Hence, a more sustainable solution arises from the development of 3d metals-catalyzed methodologies [12,13]. In fact, due to the low toxicity and vast availability, the use of earth-abundant metals such as iron, cobalt, and manganese represents a valuable and appealing area of research [12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Iron-Catalyzed C–H Functionalizations under Triazole-Assistance

Lanzi

Cera

2020

Molecules

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3d transition metals-catalyzed C-H bond functionalizations represent nowadays an important tool in organic synthesis, appearing as the most promising alternative to cross-coupling reactions. Among 3d transition metals, iron found widespread application due to its availability and benign nature, and it was established as an efficient catalyst in organic synthesis. In this context, the use of ortho-orientating directing groups (DGs) turned out to be necessary for promoting selective iron-catalyzed C-H functionalization reactions. Very recently, triazoles DGs were demonstrated to be more than an excellent alternative to the commonly employed 8-aminoquinoline (AQ) DG, as a result of their modular synthesis as well as the mild reaction conditions applied for their removal. In addition, their tunable geometry and electronics allowed for new unprecedented reactivities in iron-catalyzed C-H activation methodologies that will be summarized within this review. Scheme 2. Triazole-assisted C(sp 2 )-H arylation; (a) Aryl amides functionalizations; (b) Acrylamide functionalization; (c) Removal of TAM DG.The deprotection of TAM DG was carried out under acidic conditions, leading to ortho-arylated benzoic acid 5b in high yields (Scheme 2c). TAM DG was found applicable for C-H arylations of ferrocene derivatives 6 as well [42]. Again, the combination of diphosphine ligand dppe and 2,3dichlorobutane (2,3-DCB) as external oxidant was found essential for the transformation. The use of an in situ-formed Ar2Zn•MgBr2(TMEDA) organometallic base allowed for the conversion of amides 6a-b into racemic products 7a-b in good yields. Noteworthy, the use of a chiral ligand such as R,R-Scheme 2. Triazole-assisted C(sp 2 )-H arylation; (a) Aryl amides functionalizations; (b) Acrylamide functionalization; (c) Removal of TAM DG.The deprotection of TAM DG was carried out under acidic conditions, leading to ortho-arylated benzoic acid 5b in high yields (Scheme 2c). TAM DG was found applicable for C-H arylations of ferrocene derivatives 6 as well [42]. Again, the combination of diphosphine ligand dppe and Molecules 2020, 25, 1806 4 of 26 2,3-dichlorobutane (2,3-DCB) as external oxidant was found essential for the transformation. The use of an in situ-formed Ar 2 Zn•MgBr 2 (TMEDA) organometallic base allowed for the conversion of amides 6a-b into racemic products 7a-b in good yields. Noteworthy, the use of a chiral ligand such as R,R-chiraphos led to the formation of a planar chiral ferrocene derivative 7c with moderate enantiomeric ratio (Scheme 3). Molecules 2020, 25, x FOR PEER REVIEW 4 of 27 chiraphos led to the formation of a planar chiral ferrocene derivative 7c with moderate enantiomeric ratio (Scheme 3). Scheme 3. Iron-catalyzed C(sp 2 )-H arylation of ferrocenes aromatic rings with TAM DG.The activation of C(sp 3 )-H is generally more challenging than C(sp 2 )-H due to their lower acidity [43,44]. In analogy with previous reports on iron-catalyzed C(sp 3 )-H arylations enabled by 8-AQ DGs, TAM DG was found operative under similar conditions [...

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“…Secondly, the development of chemoselective C−H chemistry can avoid the use of C−C backbone which may result in undesired surface degradation . So far, a number of effective technologies have been developed for C−H transformations during the past decades, including organometallic and enzymes catalysis, γ‐ray initiated, and UV‐induced reactions. However, many of them often lead to an uncontrolled dissociation of chemical bonds other than C−H and result in undesired physical or chemical changes.…”

Section: Introductionmentioning

confidence: 99%

Surface Engineering of Organic Polymers by Photo‐induced Free Radical Coupling with p‐Dimethylaminophenyl Group as A Synthesis Block

et al. 2020

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This contribution presents a versatile strategy to transfer unactivated surface C–H bonds of polymeric substrates to C–R–F groups (R stands for a spacer and F stands for functional group) by UV light‐assisted surface free radical coupling. With p‐dimethylaminophenyl radical as a building block, various reactive groups, such as –CHO, –SH, –B(O)OH, –CN and –SO3−, are successfully grafted onto typical commercial polymer substrates including biaxially oriented polypropylene, polyethylene phthalate, ethylene tetrafluoroethylene copolymer and dimethyl silicone rubber. Fluorencence microscope images, X‐ray photoelectron spectroscopy, UV‐vis and fluorescence spectra support that the above functional groups are covalently bonded to the polymer substrates. The concentration of the reactive groups immobilized on the different substrates is in the order of 10−8 to 10−7 mmol mm−2 determined by UV‐vis spectrometry. In addition, as a proof‐of‐concept, the introduced functional groups are demonstrated by their special reactions, for example, –CHO reacting with –NH2 to synthesize Schiff base, –SH to detect silver ions, and the complexes of –C=N and Zn2+ to degrade Rhodamine B. The results indicate that one can fabricate an integrated molecular library on the surface of polymeric substrates at the molecular level by selecting the building blocks.

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Enantioselective C−H Activation with Earth‐Abundant 3d Transition Metals

Cited by 343 publications

References 180 publications

Ni‐Catalyzed Chelation‐Assisted Direct Functionalization of Inert C—H Bonds

Ni‐Catalyzed Chelation‐Assisted Direct Functionalization of Inert C—H Bonds

Iron-Catalyzed C–H Functionalizations under Triazole-Assistance

Surface Engineering of Organic Polymers by Photo‐induced Free Radical Coupling with p‐Dimethylaminophenyl Group as A Synthesis Block

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