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Wang J, Liu Y, Han N, Gao Y, Luo J. ortho-C(sp 3)-H arylation of aromatic aldehydes using 2-amino- N-methyl-acetamide as a L,L-type transient directing group. Org Biomol Chem 2023; 21:1878-1882. [PMID: 36789479 DOI: 10.1039/d3ob00024a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Pd-catalyzed ortho-C(sp3)-H arylation of aromatic aldehydes using 2-amino-N-methyl-acetamide as a simple, efficient and commercially available L,L-type transient directing group (TDG) is reported. The reaction exhibited excellent substrate compatibility and generated the desired products in moderate-to-high yields up to 78%. Further acid-catalyzed cyclization and dehydrative aromatization were also tested, and furnished some polycyclic aromatic hydrocarbons with excellent yields up to 96%. The X-ray crystal structure of a 2-methylbenzaldehyde ortho-C(sp3)-H palladation intermediate was obtained. Then, a plausible reaction mechanism involving the formation of a [5,6]-fused palladacycle was proposed. This approach offers valuable insights for exploiting novel L,L-type TDGs.
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Affiliation(s)
- Jinyuan Wang
- School of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
| | - Yunzhi Liu
- School of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
| | - Nan Han
- School of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
| | - Yuan Gao
- School of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
| | - Jun Luo
- School of Chemistry and Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
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Lucas EL, Lam NYS, Zhuang Z, Chan HSS, Strassfeld DA, Yu JQ. Palladium-Catalyzed Enantioselective β-C(sp 3)-H Activation Reactions of Aliphatic Acids: A Retrosynthetic Surrogate for Enolate Alkylation and Conjugate Addition. Acc Chem Res 2022; 55:537-550. [PMID: 35076221 PMCID: PMC9129890 DOI: 10.1021/acs.accounts.1c00672] [Citation(s) in RCA: 38] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Enolate alkylation and conjugate addition into an α,β-unsaturated system have served as long-standing strategic disconnections for the installation of α- or β-substituents on carbonyl-containing compounds. At the onset of our efforts to develop C-H activation reactions for organic synthesis, we set our eye toward developing asymmetric β-C-H activation reactions of aliphatic acids with the perspective that this bond-forming event could serve as a more flexible retrosynthetic surrogate for both canonical carbonyl-related asymmetric transformations.In this Account, we describe our early efforts using strongly coordinating chiral oxazolines to probe reaction mechanism and the stereochemical nature of the C-H cleavage transition state. The characterization of key reactive intermediates through X-ray crystallography and computational studies suggested a transition state with C-H and Pd-OAc bonds being approximately coplanar for optimum interaction. We then moved forward to develop more practical, weakly coordinating monodentate amide directing groups, a necessary advance toward achieving the β-C-H activation of weakly coordinating native carboxylic acids. Throughout this journey, gradual deconvolution between a substrate's directing effect and its intimate interplay with ligand properties has culminated in the design of new ligand classes that ultimately allowed the competency of native carboxylic acids in β-C-H activation. These efforts established the importance of ligand acceleration in Pd-catalyzed C-H activation, where the substrate's weak coordination is responsible for positioning the catalyst for C-H cleavage, while the direct participation from the bifunctional ligand is responsible for enthalpically stabilizing the C-H cleavage transition state.Building upon these principles, we developed five classes of chiral ligands (MPAA, MPAQ, MPAO, MPAThio, MPAAM) to enable enantioselective β-C-H activation reactions, including carbon-carbon and carbon-heteroatom bond formation. The accumulated data from our developed enantioselective C-H activation reactions indicate that ligands possessing point chirality are most effective for imparting stereoinduction in the C-H activation step, the application of which enabled the desymmetrization and subsequent C-H functionalization of enantiotopic carbon and protons across a range of weakly coordinating arylamides and, more recently, free carboxylic acids. Progress in ligand design, in conjunction with the enabling nature of alkali metal countercations, led to the realization of a suite of β-methyl and now methylene C(sp3)-H activation reactions. These advancements also enabled the use of economical oxidants, such as peroxides and molecular oxygen, to facilitate catalyst turnover. In the future, continued progress in designing more efficient bifunctional chiral ligands is likely to provide a myriad of enantioselective β-C-H activation reactions of readily available native substrates.
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Affiliation(s)
- Erika L Lucas
- Department of Chemistry, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, California 92037, United States
| | - Nelson Y S Lam
- Department of Chemistry, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, California 92037, United States
| | - Zhe Zhuang
- Department of Chemistry, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, California 92037, United States
| | - Hau Sun Sam Chan
- Department of Chemistry, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, California 92037, United States
| | - Daniel A Strassfeld
- Department of Chemistry, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, California 92037, United States
| | - Jin-Quan Yu
- Department of Chemistry, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, California 92037, United States
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Saini G, Kapur M. Palladium-catalyzed functionalizations of acidic and non-acidic C(sp 3)-H bonds - recent advances. Chem Commun (Camb) 2021; 57:1693-1714. [PMID: 33492315 DOI: 10.1039/d0cc06892f] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A tremendous upsurge has been seen in the recent decade for the proximal and remote functionalization of activated and unactivated substrates via palladium redox pathways. This feature article discusses some of the recent reports on direct as well as indirect C(sp3)-H functionalization via cross-coupling reactions under palladium catalysis. Activated substrates (possessing acidic C(sp3)-H) including enones, ketones, aldehydes, silylenol ethers, esters, silyl ketene acetals, amides, cyano, α-amino esters, and O-carbamates, capable of undergoing cross-coupling reactions at the α-, β-, γ-, δ- and ε-positions, will be discussed. To overcome the challenging task of achieving regioselectivity, a variety of innovative modifications have been reported. The reports of C-H activations based on directing group, and as native functionality have been illustrated at the β-, γ- and δ-positions. Substrates such as α-amino esters, carbonyls, carboxylic acids and their derivatives, afford site-selective C(sp3)-H functionalization via varied-sized reactive metallacycles and are a unique class of substrates whose C(sp3)-H functionalizations were earlier considered as very difficult.
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Affiliation(s)
- Gaurav Saini
- Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal Bypass Road, Bhauri, Bhopal 462066, MP, India.
| | - Manmohan Kapur
- Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal Bypass Road, Bhauri, Bhopal 462066, MP, India.
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Gramage-Doria R. Steering Site-Selectivity in Transition Metal-Catalyzed C-H Bond Functionalization: the Challenge of Benzanilides. Chemistry 2020; 26:9688-9709. [PMID: 32237177 DOI: 10.1002/chem.202000672] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 03/18/2020] [Indexed: 12/31/2022]
Abstract
Selective C-H bond functionalization catalyzed by metal complexes have completely revolutionized the way in which chemical synthesis is conceived nowadays. Typically, the reactivity of a transition metal catalyst is the key to control the site-, regio- and/or stereo-selectivity of a C-H bond functionalization. Of particular interests are molecules that contain multiple C-H bonds prone to undergo C-H bond activations with very similar bond dissociation energies at different positions. This is the case of benzanilides, relevant chemical motifs that are found in many useful fine chemicals, in which two C-H sites are present in chemically different aromatic fragments. In the last years, it has been found that depending on the metal catalyst and the reaction conditions, the amide motif might behave as a directing group towards the metal-catalyzed C-H bond activation in the benzamide site or in the anilide site. The impact and the consequences of such subtle control of site-selectivity are herein reviewed with important applications in carbon-carbon and carbon-heteroatom bond forming processes. The mechanisms unraveling these unique transformations are discussed in order to provide a better understanding for future developments in the field of site-selective C-H bond functionalization with transition metal catalysts.
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Gryaznova TV, Khrizanforov MN, Levitskaya AI, Kh.Rizvanov I, Balakina MY, Ivshin KA, Kataeva ON, Budnikova YH. Electrochemically Driven and Acid-Driven Pyridine-Directed ortho-Phosphorylation of C(sp2)–H Bonds. Organometallics 2020. [DOI: 10.1021/acs.organomet.0c00247] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Tatyana V. Gryaznova
- Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center, Russian Academy of Sciences, Arbuzov-str., 8, Kazan 420088, Russian Federation
| | - Mikhail N. Khrizanforov
- Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center, Russian Academy of Sciences, Arbuzov-str., 8, Kazan 420088, Russian Federation
| | - Alina I. Levitskaya
- Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center, Russian Academy of Sciences, Arbuzov-str., 8, Kazan 420088, Russian Federation
| | - Ildar Kh.Rizvanov
- Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center, Russian Academy of Sciences, Arbuzov-str., 8, Kazan 420088, Russian Federation
| | - Marina Yu. Balakina
- Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center, Russian Academy of Sciences, Arbuzov-str., 8, Kazan 420088, Russian Federation
| | - Kamil A. Ivshin
- Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center, Russian Academy of Sciences, Arbuzov-str., 8, Kazan 420088, Russian Federation
| | - Olga N. Kataeva
- Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center, Russian Academy of Sciences, Arbuzov-str., 8, Kazan 420088, Russian Federation
| | - Yulia H. Budnikova
- Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center, Russian Academy of Sciences, Arbuzov-str., 8, Kazan 420088, Russian Federation
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