1
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Behera RR, Saha R, Kumar AA, Sethi S, Jana NC, Bagh B. Hydrosilylation of Terminal Alkynes Catalyzed by an Air-Stable Manganese-NHC Complex. J Org Chem 2023. [PMID: 37317486 DOI: 10.1021/acs.joc.3c00127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
In recent years, catalysis with base metal manganese has received a significant amount of interest. Catalysis with manganese complexes having N-heterocyclic carbenes (NHCs) is relatively underdeveloped in comparison to the extensively investigated manganese catalysts possessing pincer ligands (particularly phosphine-based ligands). Herein, we describe the synthesis of two imidazolium salts decorated with picolyl arms (L1 and L2) as NHC precursors. Facile coordination of L1 and L2 with MnBr(CO)5 in the presence of a base resulted in the formation manganese(I)-NHC complexes (1 and 2) as an air-stable solid in good isolated yield. Single-crystal X-ray analysis revealed the structure of the cationic complexes [Mn(CO)3(NHC)][PF6] with tridentate N,C,N binding of the NHC ligand in a facile fashion. Along with a few known manganese(I) complexes, these Mn(I)-NHC complexes 1 and 2 were tested for the hydrosilylation of terminal alkynes. Complex 1 was proved to be an effective catalyst for the hydrosilylation of terminal alkynes with good selectivity toward the less thermodynamically stable β-(Z)-vinylsilanes. This method provided good regioselectivity (anti-Markovnikov addition) and stereoselectivity (β-(Z)-product). Experimental evidence suggested that the present hydrosilylation pathway involved an organometallic mechanism with manganese(I)-silyl species as a possible reactive intermediate.
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Affiliation(s)
- Rakesh R Behera
- School of Chemical Sciences, National Institute of Science Education and Research (NISER), An OCC of Homi Bhabha National Institute, PO Bhimpur-Padanpur, Via Jatni, District Khurda, Bhubaneswar, Odisha 752050, India
| | - Ratnakar Saha
- School of Chemical Sciences, National Institute of Science Education and Research (NISER), An OCC of Homi Bhabha National Institute, PO Bhimpur-Padanpur, Via Jatni, District Khurda, Bhubaneswar, Odisha 752050, India
| | - Alamsaty Ashis Kumar
- School of Chemical Sciences, National Institute of Science Education and Research (NISER), An OCC of Homi Bhabha National Institute, PO Bhimpur-Padanpur, Via Jatni, District Khurda, Bhubaneswar, Odisha 752050, India
| | - Subrat Sethi
- School of Chemical Sciences, National Institute of Science Education and Research (NISER), An OCC of Homi Bhabha National Institute, PO Bhimpur-Padanpur, Via Jatni, District Khurda, Bhubaneswar, Odisha 752050, India
| | - Narayan Ch Jana
- School of Chemical Sciences, National Institute of Science Education and Research (NISER), An OCC of Homi Bhabha National Institute, PO Bhimpur-Padanpur, Via Jatni, District Khurda, Bhubaneswar, Odisha 752050, India
| | - Bidraha Bagh
- School of Chemical Sciences, National Institute of Science Education and Research (NISER), An OCC of Homi Bhabha National Institute, PO Bhimpur-Padanpur, Via Jatni, District Khurda, Bhubaneswar, Odisha 752050, India
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2
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Almutairi N, Vijjamarri S, Du G. Manganese Salan Complexes as Catalysts for Hydrosilylation of Aldehydes and Ketones. Catalysts 2023. [DOI: 10.3390/catal13040665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/30/2023] Open
Abstract
Manganese has attracted significant recent attention due to its abundance, low toxicity, and versatility in catalysis. In the present study, a series of manganese (III) complexes supported by salan ligands have been synthesized and characterized, and their activity as catalysts in the hydrosilylation of carbonyl compounds was examined. While manganese (III) chloride complexes exhibited minimal catalytic efficacy without activation of silver perchlorate, manganese (III) azide complexes showed good activity in the hydrosilylation of carbonyl compounds. Under optimized reaction conditions, several types of aldehydes and ketones could be reduced with good yields and tolerance to a variety of functional groups. The possible mechanisms of silane activation and hydrosilylation were discussed in light of relevant experimental observations.
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3
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Das K, Waiba S, Jana A, Maji B. Manganese-catalyzed hydrogenation, dehydrogenation, and hydroelementation reactions. Chem Soc Rev 2022; 51:4386-4464. [PMID: 35583150 DOI: 10.1039/d2cs00093h] [Citation(s) in RCA: 44] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The emerging field of organometallic catalysis has shifted towards research on Earth-abundant transition metals due to their ready availability, economic advantage, and novel properties. In this case, manganese, the third most abundant transition-metal in the Earth's crust, has emerged as one of the leading competitors. Accordingly, a large number of molecularly-defined Mn-complexes has been synthesized and employed for hydrogenation, dehydrogenation, and hydroelementation reactions. In this regard, catalyst design is based on three pillars, namely, metal-ligand bifunctionality, ligand hemilability, and redox activity. Indeed, the developed catalysts not only differ in the number of chelating atoms they possess but also their working principles, thereby leading to different turnover numbers for product molecules. Hence, the critical assessment of molecularly defined manganese catalysts in terms of chelating atoms, reaction conditions, mechanistic pathway, and product turnover number is significant. Herein, we analyze manganese complexes for their catalytic activity, versatility to allow multiple transformations and their routes to convert substrates to target molecules. This article will also be helpful to get significant insight into ligand design, thereby aiding catalysis design.
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Affiliation(s)
- Kuhali Das
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, 741246, India.
| | - Satyadeep Waiba
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, 741246, India.
| | - Akash Jana
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, 741246, India.
| | - Biplab Maji
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, 741246, India.
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4
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Abstract
AbstractRecent developments in manganese-catalyzed reducing transformations—hydrosilylation, hydroboration, hydrogenation, and transfer hydrogenation—are reviewed herein. Over the past half a decade (i.e., 2016 to the present), more than 115 research publications have been reported in these fields. Novel organometallic compounds and new reduction transformations have been discovered and further developed. Significant challenges that had historically acted as barriers for the use of manganese catalysts in reduction reactions are slowly being broken down. This review will hopefully assist in developing this research area, by presenting a clear and concise overview of the catalyst structures and substrate transformations published so far.1 Introduction2 Hydrosilylation3 Hydroboration4 Hydrogenation5 Transfer Hydrogenation6 Conclusion and Perspective
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Affiliation(s)
- Christophe Werlé
- Max Planck Institute for Chemical Energy Conversion
- Ruhr University Bochum
| | - Peter Schlichter
- Max Planck Institute for Chemical Energy Conversion
- Institut für Technische und Makromolekulare Chemie (ITMC), RWTH Aachen University
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5
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Ghosh P, Jacobi von Wangelin A. Manganese‐Catalyzed Hydroborations with Broad Scope. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202103550] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Pradip Ghosh
- Dept. of Chemistry University of Hamburg Martin Luther King Pl 6 20146 Hamburg Germany
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6
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Ghosh P, Jacobi von Wangelin A. Manganese-Catalyzed Hydroborations with Broad Scope. Angew Chem Int Ed Engl 2021; 60:16035-16043. [PMID: 33894033 PMCID: PMC8362021 DOI: 10.1002/anie.202103550] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 04/22/2021] [Indexed: 12/29/2022]
Abstract
Reductive transformations of easily available oxidized matter are at the heart of synthetic manipulation and chemical valorization. The applications of catalytic hydrofunctionalization benefit from the use of liquid reducing agents and operationally facile setups. Metal‐catalyzed hydroborations provide a highly prolific platform for reductive valorizations of stable C=X electrophiles. Here, we report an especially facile, broad‐scope reduction of various functions including carbonyls, carboxylates, pyridines, carbodiimides, and carbonates under very mild conditions with the inexpensive pre‐catalyst Mn(hmds)2. The reaction could be successfully applied to depolymerizations.
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Affiliation(s)
- Pradip Ghosh
- Dept. of Chemistry, University of Hamburg, Martin Luther King Pl 6, 20146, Hamburg, Germany
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7
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Antico E, Schlichter P, Werlé C, Leitner W. Reduction of Carboxylic Acids to Alcohols via Manganese(I) Catalyzed Hydrosilylation. JACS AU 2021; 1:742-749. [PMID: 34467330 PMCID: PMC8395667 DOI: 10.1021/jacsau.1c00140] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The reduction of carboxylic acids to the respective alcohols, in mild conditions, was achieved using [MnBr(CO)5] as the catalyst and bench stable PhSiH3 as the reducing agent. It was shown that the reaction with the earth-abundant metal catalyst could be performed either with a catalyst loading as low as 0.5 mol %, rare with the use of [MnBr(CO)5], or on a gram scale employing only 1.5 equiv of PhSiH3, the lowest amount of silane reported to date for this transformation. Kinetic data and control experiments have provided initial insight into the mechanism of the catalytic process, suggesting that it proceeds via the formation of silyl ester intermediates and ligand dissociation to generate a coordinatively unsaturated Mn(I) complex as the active species.
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Affiliation(s)
- Emanuele Antico
- Max
Planck Institute for Chemical Energy Conversion, Stiftstr. 34−36, 45470 Mülheim an der Ruhr, Germany
- Institut
für Technische und Makromolekulare Chemie (ITMC), RWTH Aachen University, Worringer Weg 2, 52074 Aachen, Germany
| | - Peter Schlichter
- Max
Planck Institute for Chemical Energy Conversion, Stiftstr. 34−36, 45470 Mülheim an der Ruhr, Germany
- Institut
für Technische und Makromolekulare Chemie (ITMC), RWTH Aachen University, Worringer Weg 2, 52074 Aachen, Germany
| | - Christophe Werlé
- Max
Planck Institute for Chemical Energy Conversion, Stiftstr. 34−36, 45470 Mülheim an der Ruhr, Germany
- Ruhr
University Bochum, Universitätsstr.
150, 44801 Bochum, Germany
| | - Walter Leitner
- Max
Planck Institute for Chemical Energy Conversion, Stiftstr. 34−36, 45470 Mülheim an der Ruhr, Germany
- Institut
für Technische und Makromolekulare Chemie (ITMC), RWTH Aachen University, Worringer Weg 2, 52074 Aachen, Germany
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8
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Weber S, Iebed D, Glatz M, Kirchner K. Reduction of carbonyl compounds via hydrosilylation catalyzed by well-defined PNP-Mn(I) hydride complexes. MONATSHEFTE FUR CHEMIE 2021. [DOI: 10.1007/s00706-021-02774-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
AbstractReduction reactions of unsaturated compounds are fundamental transformations in synthetic chemistry. In this context, the reduction of polarized double bonds such as carbonyl or C=C motifs can be achieved by hydrogenation reactions. We describe here a highly chemoselective Mn(I)-based PNP pincer catalyst for the hydrosilylation of aldehydes and ketones employing polymethylhydrosiloxane (PMHS) as inexpensive hydrogen donor.
Graphic abstract
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9
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Zhang GY, Ruan SH, Li YY, Gao JX. Manganese catalyzed asymmetric transfer hydrogenation of ketones. CHINESE CHEM LETT 2021. [DOI: 10.1016/j.cclet.2020.10.023] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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10
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Saito K, Ito T, Arata S, Sunada Y. Four‐Coordinated Manganese(II) Disilyl Complexes for the Hydrosilylation of Aldehydes and Ketones with 1,1,3,3‐Tetramethyldisiloxane. ChemCatChem 2020. [DOI: 10.1002/cctc.202001522] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Kyoka Saito
- Department of Applied Chemistry Faculty of Science and Engineering Chuo University 1-13-27 Kasuga Bunkyo-ku Tokyo Japan
| | - Tatsuyoshi Ito
- Kanagawa Institute of Industrial Science and Technology (KISTEC) 4-6-1 Komaba Meguro-ku Tokyo Japan
| | - Shogo Arata
- Department of Applied Chemistry School of Engineering The University of Tokyo 4-6-1 Komaba Meguro-ku Tokyo Japan
| | - Yusuke Sunada
- Department of Applied Chemistry School of Engineering The University of Tokyo 4-6-1 Komaba Meguro-ku Tokyo Japan
- Institute of Industrial Science The University of Tokyo 4-6-1 Komaba Meguro-ku Tokyo Japan
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11
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Ganguli K, Mandal A, Sarkar B, Kundu S. Benzimidazole fragment containing Mn-complex catalyzed hydrosilylation of ketones and nitriles. Tetrahedron 2020. [DOI: 10.1016/j.tet.2020.131439] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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12
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Uvarov VM, de Vekki DA. Recent progress in the development of catalytic systems for homogenous asymmetric hydrosilylation of ketones. J Organomet Chem 2020. [DOI: 10.1016/j.jorganchem.2020.121415] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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13
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Behera RR, Ghosh R, Panda S, Khamari S, Bagh B. Hydrosilylation of Esters Catalyzed by Bisphosphine Manganese(I) Complex: Selective Transformation of Esters to Alcohols. Org Lett 2020; 22:3642-3648. [PMID: 32271582 DOI: 10.1021/acs.orglett.0c01144] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Selective and efficient hydrosilylations of esters to alcohols by a well-defined manganese(I) complex with a commercially available bisphosphine ligand are described. These reactions are easy alternatives for stoichiometric hydride reduction or hydrogenation, and employing cheap, abundant, and nonprecious metal is attractive. The hydrosilylations were performed at 100 °C under solvent-free conditions with low catalyst loading. A large variety of aromatic, aliphatic, and cyclic esters bearing different functional groups were selectively converted into the corresponding alcohols in good yields.
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Affiliation(s)
- Rakesh R Behera
- School of Chemical Sciences, National Institute of Science Education and Research (NISER), HBNI, PO Bhimpur-Padanpur, Via Jatni, District Khurda, Bhubaneswar, Odisha 752050, India
| | - Rahul Ghosh
- School of Chemical Sciences, National Institute of Science Education and Research (NISER), HBNI, PO Bhimpur-Padanpur, Via Jatni, District Khurda, Bhubaneswar, Odisha 752050, India
| | - Surajit Panda
- School of Chemical Sciences, National Institute of Science Education and Research (NISER), HBNI, PO Bhimpur-Padanpur, Via Jatni, District Khurda, Bhubaneswar, Odisha 752050, India
| | - Subrat Khamari
- School of Chemical Sciences, National Institute of Science Education and Research (NISER), HBNI, PO Bhimpur-Padanpur, Via Jatni, District Khurda, Bhubaneswar, Odisha 752050, India
| | - Bidraha Bagh
- School of Chemical Sciences, National Institute of Science Education and Research (NISER), HBNI, PO Bhimpur-Padanpur, Via Jatni, District Khurda, Bhubaneswar, Odisha 752050, India
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14
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Brzozowska A, Zubar V, Ganardi RC, Rueping M. Chemoselective Hydroboration of Propargylic Alcohols and Amines Using a Manganese(II) Catalyst. Org Lett 2020; 22:3765-3769. [DOI: 10.1021/acs.orglett.0c00941] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Aleksandra Brzozowska
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany
| | - Viktoriia Zubar
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany
| | - Ruth-Christine Ganardi
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany
| | - Magnus Rueping
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany
- KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
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15
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Liu W, Guo J, Xing S, Lu Z. Highly Enantioselective Cobalt-Catalyzed Hydroboration of Diaryl Ketones. Org Lett 2020; 22:2532-2536. [DOI: 10.1021/acs.orglett.0c00293] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Wenbo Liu
- Department of Chemistry, Zhejiang University, Hangzhou 310058, China
| | - Jun Guo
- Department of Chemistry, Zhejiang University, Hangzhou 310058, China
| | - Shipei Xing
- Department of Chemistry, Zhejiang University, Hangzhou 310058, China
| | - Zhan Lu
- Department of Chemistry, Zhejiang University, Hangzhou 310058, China
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16
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Kaithal A, van Bonn P, Hölscher M, Leitner W. Manganese(I)-Catalyzed β-Methylation of Alcohols Using Methanol as C 1 Source. Angew Chem Int Ed Engl 2020; 59:215-220. [PMID: 31651071 PMCID: PMC6973237 DOI: 10.1002/anie.201909035] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 09/27/2019] [Indexed: 01/01/2023]
Abstract
Highly selective β-methylation of alcohols was achieved using an earth-abundant first row transition metal in the air stable molecular manganese complex [Mn(CO)2 Br[HN(C2 H4 Pi Pr2 )2 ]] 1 ([HN(C2 H4 Pi Pr2 )2 ]=MACHO-i Pr). The reaction requires only low loadings of 1 (0.5 mol %), methanolate as base and MeOH as methylation reagent as well as solvent. Various alcohols were β-methylated with very good selectivity (>99 %) and excellent yield (up to 94 %). Biomass derived aliphatic alcohols and diols were also selectively methylated on the β-position, opening a pathway to "biohybrid" molecules constructed entirely from non-fossil carbon. Mechanistic studies indicate that the reaction proceeds through a borrowing hydrogen pathway involving metal-ligand cooperation at the Mn-pincer complex. This transformation provides a convenient, economical, and environmentally benign pathway for the selective C-C bond formation with potential applications for the preparation of advanced biofuels, fine chemicals, and biologically active molecules.
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Affiliation(s)
- Akash Kaithal
- Institut für Technische und Makromolekulare ChemieRWTH Aachen UniversityWorringer Weg 252074AachenGermany
| | - Pit van Bonn
- Institut für Technische und Makromolekulare ChemieRWTH Aachen UniversityWorringer Weg 252074AachenGermany
| | - Markus Hölscher
- Institut für Technische und Makromolekulare ChemieRWTH Aachen UniversityWorringer Weg 252074AachenGermany
| | - Walter Leitner
- Institut für Technische und Makromolekulare ChemieRWTH Aachen UniversityWorringer Weg 252074AachenGermany
- Max-Planck-Institut für chemische EnergiekonversionStiftstraße 34–3645470Mülheim a.d. RuhrGermany
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17
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Zhang G, Zeng H, Li S, Johnson J, Mo Z, Neary MC, Zheng S. 1-D manganese(ii)-terpyridine coordination polymers as precatalysts for hydrofunctionalisation of carbonyl compounds. Dalton Trans 2020; 49:2610-2615. [PMID: 32037438 DOI: 10.1039/c9dt04637b] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Efficient hydroboration and hydrosilylation of ketones and aldehydes has been achieved using a MnII-coordination polymer as precatalyst under mild conditions.
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Affiliation(s)
- Guoqi Zhang
- Department of Sciences
- John Jay College and Ph.D. Program in Chemistry
- The Graduate Center of the City University of New York
- New York
- USA
| | - Haisu Zeng
- Department of Sciences
- John Jay College and Ph.D. Program in Chemistry
- The Graduate Center of the City University of New York
- New York
- USA
| | - Sihan Li
- Department of Sciences
- John Jay College and Ph.D. Program in Chemistry
- The Graduate Center of the City University of New York
- New York
- USA
| | - Jahvon Johnson
- Department of Sciences
- John Jay College and Ph.D. Program in Chemistry
- The Graduate Center of the City University of New York
- New York
- USA
| | - Zixuan Mo
- Department of Sciences
- John Jay College and Ph.D. Program in Chemistry
- The Graduate Center of the City University of New York
- New York
- USA
| | - Michelle C. Neary
- Department of Chemistry
- Hunter College
- the City University of New York
- New York
- USA
| | - Shengping Zheng
- Department of Chemistry
- Hunter College
- the City University of New York
- New York
- USA
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18
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Kaithal A, Bonn P, Hölscher M, Leitner W. Manganese(I)‐Catalyzed β‐Methylation of Alcohols Using Methanol as C
1
Source. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201909035] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Akash Kaithal
- Institut für Technische und Makromolekulare Chemie RWTH Aachen University Worringer Weg 2 52074 Aachen Germany
| | - Pit Bonn
- Institut für Technische und Makromolekulare Chemie RWTH Aachen University Worringer Weg 2 52074 Aachen Germany
| | - Markus Hölscher
- Institut für Technische und Makromolekulare Chemie RWTH Aachen University Worringer Weg 2 52074 Aachen Germany
| | - Walter Leitner
- Institut für Technische und Makromolekulare Chemie RWTH Aachen University Worringer Weg 2 52074 Aachen Germany
- Max-Planck-Institut für chemische Energiekonversion Stiftstraße 34–36 45470 Mülheim a.d. Ruhr Germany
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19
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Sousa SCA, Carrasco CJ, Pinto MF, Royo B. A Manganese N‐Heterocyclic Carbene Catalyst for Reduction of Sulfoxides with Silanes. ChemCatChem 2019. [DOI: 10.1002/cctc.201900662] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Sara C. A. Sousa
- ITQB NOVA, Instituto de Tecnologia Química e BiológicaUniversidade Nova de Lisboa Av. da República 2780-157 Oeiras Portugal
| | - Carlos J. Carrasco
- ITQB NOVA, Instituto de Tecnologia Química e BiológicaUniversidade Nova de Lisboa Av. da República 2780-157 Oeiras Portugal
| | - Mara F. Pinto
- ITQB NOVA, Instituto de Tecnologia Química e BiológicaUniversidade Nova de Lisboa Av. da República 2780-157 Oeiras Portugal
| | - Beatriz Royo
- ITQB NOVA, Instituto de Tecnologia Química e BiológicaUniversidade Nova de Lisboa Av. da República 2780-157 Oeiras Portugal
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20
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Ling F, Hou H, Chen J, Nian S, Yi X, Wang Z, Song D, Zhong W. Highly Enantioselective Synthesis of Chiral Benzhydrols via Manganese Catalyzed Asymmetric Hydrogenation of Unsymmetrical Benzophenones Using an Imidazole-Based Chiral PNN Tridentate Ligand. Org Lett 2019; 21:3937-3941. [DOI: 10.1021/acs.orglett.9b01056] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Fei Ling
- Key Laboratory for Green Pharmaceutical Technologies and Related Equipment of Ministry of Education, College of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou 310014, People’s Republic of China
| | - Huacui Hou
- Key Laboratory for Green Pharmaceutical Technologies and Related Equipment of Ministry of Education, College of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou 310014, People’s Republic of China
| | - Jiachen Chen
- Key Laboratory for Green Pharmaceutical Technologies and Related Equipment of Ministry of Education, College of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou 310014, People’s Republic of China
| | - Sanfei Nian
- Key Laboratory for Green Pharmaceutical Technologies and Related Equipment of Ministry of Education, College of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou 310014, People’s Republic of China
| | - Xiao Yi
- Key Laboratory for Green Pharmaceutical Technologies and Related Equipment of Ministry of Education, College of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou 310014, People’s Republic of China
| | - Ze Wang
- Key Laboratory for Green Pharmaceutical Technologies and Related Equipment of Ministry of Education, College of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou 310014, People’s Republic of China
| | - Dingguo Song
- Key Laboratory for Green Pharmaceutical Technologies and Related Equipment of Ministry of Education, College of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou 310014, People’s Republic of China
| | - Weihui Zhong
- Key Laboratory for Green Pharmaceutical Technologies and Related Equipment of Ministry of Education, College of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou 310014, People’s Republic of China
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21
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Barman MK, Das K, Maji B. Selective Hydroboration of Carboxylic Acids with a Homogeneous Manganese Catalyst. J Org Chem 2019; 84:1570-1579. [PMID: 30632374 DOI: 10.1021/acs.joc.8b03108] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Catalytic reduction of carboxylic acid to the corresponding alcohol is a challenging task of great importance for the production of a variety of value-added chemicals. Herein, a manganese-catalyzed chemoselective hydroboration of carboxylic acids has been developed with a high turnover number (>99 000) and turnover frequency (>2000 h-1) at 25 °C. This method displayed tolerance of electronically and sterically differentiated substrates with high chemoselectivity. Importantly, aliphatic long-chain fatty acids, including biomass-derived compounds, can efficiently be reduced. Mechanistic studies revealed that the reaction occurs through the formation of active manganese-hydride species via an insertion and bond metathesis type mechanism.
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Affiliation(s)
- Milan K Barman
- Department of Chemical Sciences , Indian Institute of Science Education and Research Kolkata , Mohanpur 741246 , India
| | - Kuhali Das
- Department of Chemical Sciences , Indian Institute of Science Education and Research Kolkata , Mohanpur 741246 , India
| | - Biplab Maji
- Department of Chemical Sciences , Indian Institute of Science Education and Research Kolkata , Mohanpur 741246 , India
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22
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Alig L, Fritz M, Schneider S. First-Row Transition Metal (De)Hydrogenation Catalysis Based On Functional Pincer Ligands. Chem Rev 2018; 119:2681-2751. [PMID: 30596420 DOI: 10.1021/acs.chemrev.8b00555] [Citation(s) in RCA: 483] [Impact Index Per Article: 80.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The use of 3d metals in de/hydrogenation catalysis has emerged as a competitive field with respect to "traditional" precious metal catalyzed transformations. The introduction of functional pincer ligands that can store protons and/or electrons as expressed by metal-ligand cooperativity and ligand redox-activity strongly stimulated this development as a conceptual starting point for rational catalyst design. This review aims at providing a comprehensive picture of the utilization of functional pincer ligands in first-row transition metal hydrogenation and dehydrogenation catalysis and related synthetic concepts relying on these such as the hydrogen borrowing methodology. Particular emphasis is put on the implementation and relevance of cooperating and redox-active pincer ligands within the mechanistic scenarios.
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Affiliation(s)
- Lukas Alig
- Universität Göttingen , Institut für Anorganische Chemie , Tammannstrasse 4 , D-37077 Göttingen , Germany
| | - Maximilian Fritz
- Universität Göttingen , Institut für Anorganische Chemie , Tammannstrasse 4 , D-37077 Göttingen , Germany
| | - Sven Schneider
- Universität Göttingen , Institut für Anorganische Chemie , Tammannstrasse 4 , D-37077 Göttingen , Germany
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Morales‐Cerrada R, Fliedel C, Daran J, Gayet F, Ladmiral V, Améduri B, Poli R. Fluoroalkyl Radical Generation by Homolytic Bond Dissociation in Pentacarbonylmanganese Derivatives. Chemistry 2018; 25:296-308. [PMID: 30230633 DOI: 10.1002/chem.201804007] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2018] [Revised: 09/17/2018] [Indexed: 11/10/2022]
Affiliation(s)
- Roberto Morales‐Cerrada
- CNRSLCC (Laboratoire de Chimie de Coordination)Université de Toulouse, UPS, INPT 205 route de Narbonne, BP 44099 31077 Toulouse Cedex 4 France
- ICGMUniv MontpellierCNRS, ENSCM Place Eugène Bataillon 34095 Montpellier France
| | - Christophe Fliedel
- CNRSLCC (Laboratoire de Chimie de Coordination)Université de Toulouse, UPS, INPT 205 route de Narbonne, BP 44099 31077 Toulouse Cedex 4 France
| | - Jean‐Claude Daran
- CNRSLCC (Laboratoire de Chimie de Coordination)Université de Toulouse, UPS, INPT 205 route de Narbonne, BP 44099 31077 Toulouse Cedex 4 France
| | - Florence Gayet
- CNRSLCC (Laboratoire de Chimie de Coordination)Université de Toulouse, UPS, INPT 205 route de Narbonne, BP 44099 31077 Toulouse Cedex 4 France
| | - Vincent Ladmiral
- ICGMUniv MontpellierCNRS, ENSCM Place Eugène Bataillon 34095 Montpellier France
| | - Bruno Améduri
- ICGMUniv MontpellierCNRS, ENSCM Place Eugène Bataillon 34095 Montpellier France
| | - Rinaldo Poli
- CNRSLCC (Laboratoire de Chimie de Coordination)Université de Toulouse, UPS, INPT 205 route de Narbonne, BP 44099 31077 Toulouse Cedex 4 France
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Erken C, Kaithal A, Sen S, Weyhermüller T, Hölscher M, Werlé C, Leitner W. Manganese-catalyzed hydroboration of carbon dioxide and other challenging carbonyl groups. Nat Commun 2018; 9:4521. [PMID: 30375381 PMCID: PMC6207666 DOI: 10.1038/s41467-018-06831-9] [Citation(s) in RCA: 88] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2018] [Accepted: 09/28/2018] [Indexed: 11/09/2022] Open
Abstract
Reductive functionalization of the C=O unit in carboxylic acids, carbonic acid derivatives, and ultimately in carbon dioxide itself is a challenging task of key importance for the synthesis of value-added chemicals. In particular, it can open novel pathways for the valorization of non-fossil feedstocks. Catalysts based on earth-abundant, cheap, and benign metals would greatly contribute to the development of sustainable synthetic processes derived from this concept. Herein, a manganese pincer complex [Mn(Ph2PCH2SiMe2)2NH(CO)2Br] (1) is reported to enable the reduction of a broad range of carboxylic acids, carbonates, and even CO2 using pinacolborane as reducing agent. The complex is shown to operate under mild reaction conditions (80-120 °C), low catalyst loadings (0.1-0.2 mol%) and runs under solvent-less conditions. Mechanistic studies including crystallographic characterisation of a borane adduct of the pincer complex (1) imply that metal-ligand cooperation facilitates substrate activation.
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Affiliation(s)
- Christina Erken
- Max-Planck-Institute for Chemical Energy Conversion, Stiftstraße 34-36, 45470, Mülheim an der Ruhr, Germany
- Institut für Technische und Makromolekulare Chemie, RWTH Aachen University, Worringer Weg 2, 52074, Aachen, Germany
| | - Akash Kaithal
- Institut für Technische und Makromolekulare Chemie, RWTH Aachen University, Worringer Weg 2, 52074, Aachen, Germany
| | - Suman Sen
- Institut für Technische und Makromolekulare Chemie, RWTH Aachen University, Worringer Weg 2, 52074, Aachen, Germany
| | - Thomas Weyhermüller
- Max-Planck-Institute for Chemical Energy Conversion, Stiftstraße 34-36, 45470, Mülheim an der Ruhr, Germany
| | - Markus Hölscher
- Institut für Technische und Makromolekulare Chemie, RWTH Aachen University, Worringer Weg 2, 52074, Aachen, Germany
| | - Christophe Werlé
- Max-Planck-Institute for Chemical Energy Conversion, Stiftstraße 34-36, 45470, Mülheim an der Ruhr, Germany
| | - Walter Leitner
- Max-Planck-Institute for Chemical Energy Conversion, Stiftstraße 34-36, 45470, Mülheim an der Ruhr, Germany.
- Institut für Technische und Makromolekulare Chemie, RWTH Aachen University, Worringer Weg 2, 52074, Aachen, Germany.
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25
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Ma X, Qiao L, Liu G, Huang Z. A New Phosphine-Amine-Oxazoline Ligand for Ru-Catalyzed Asymmetric Hydrogenation ofN-Phosphinylimines. CHINESE J CHEM 2018. [DOI: 10.1002/cjoc.201800343] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Xiaochen Ma
- State Key laboratory of Organometallic Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences; 345 Lingling Rd, Shanghai 200032 China
| | - Lin Qiao
- State Key laboratory of Organometallic Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences; 345 Lingling Rd, Shanghai 200032 China
| | - Guixia Liu
- State Key laboratory of Organometallic Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences; 345 Lingling Rd, Shanghai 200032 China
| | - Zheng Huang
- State Key laboratory of Organometallic Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences; 345 Lingling Rd, Shanghai 200032 China
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Yang X, Wang C. Diverse Fates of β-Silyl Radical under Manganese Catalysis: Hydrosilylation and Dehydrogenative Silylation of Alkenes. CHINESE J CHEM 2018. [DOI: 10.1002/cjoc.201800367] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Xiaoxu Yang
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences; Beijing 100190 China
- University of Chinese Academy of Sciences; Beijing 100049 China
| | - Congyang Wang
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences; Beijing 100190 China
- University of Chinese Academy of Sciences; Beijing 100049 China
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27
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Carney JR, Dillon BR, Campbell L, Thomas SP. Manganese‐Catalyzed Hydrofunctionalization of Alkenes. Angew Chem Int Ed Engl 2018; 57:10620-10624. [DOI: 10.1002/anie.201805483] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Indexed: 11/06/2022]
Affiliation(s)
- Jonathan R. Carney
- EaStCHEM School of ChemistryUniversity of Edinburgh Joseph Black Building, David Brewster Road Edinburgh EH9 3FJ UK
| | | | | | - Stephen P. Thomas
- EaStCHEM School of ChemistryUniversity of Edinburgh Joseph Black Building, David Brewster Road Edinburgh EH9 3FJ UK
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28
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Carney JR, Dillon BR, Campbell L, Thomas SP. Manganese‐Catalyzed Hydrofunctionalization of Alkenes. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201805483] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Jonathan R. Carney
- EaStCHEM School of ChemistryUniversity of Edinburgh Joseph Black Building, David Brewster Road Edinburgh EH9 3FJ UK
| | | | | | - Stephen P. Thomas
- EaStCHEM School of ChemistryUniversity of Edinburgh Joseph Black Building, David Brewster Road Edinburgh EH9 3FJ UK
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Ling F, Nian S, Chen J, Luo W, Wang Z, Lv Y, Zhong W. Development of Ferrocene-Based Diamine-Phosphine-Sulfonamide Ligands for Iridium-Catalyzed Asymmetric Hydrogenation of Ketones. J Org Chem 2018; 83:10749-10761. [DOI: 10.1021/acs.joc.8b01276] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Fei Ling
- Key Laboratory for Green Pharmaceutical Technologies and Related Equipment of Ministry of Education, College of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou 310014, People’s Republic of China
| | - Sanfei Nian
- Key Laboratory for Green Pharmaceutical Technologies and Related Equipment of Ministry of Education, College of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou 310014, People’s Republic of China
| | - Jiachen Chen
- Key Laboratory for Green Pharmaceutical Technologies and Related Equipment of Ministry of Education, College of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou 310014, People’s Republic of China
| | - Wenjun Luo
- Key Laboratory for Green Pharmaceutical Technologies and Related Equipment of Ministry of Education, College of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou 310014, People’s Republic of China
| | - Ze Wang
- Key Laboratory for Green Pharmaceutical Technologies and Related Equipment of Ministry of Education, College of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou 310014, People’s Republic of China
| | - Yaping Lv
- Key Laboratory for Green Pharmaceutical Technologies and Related Equipment of Ministry of Education, College of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou 310014, People’s Republic of China
| | - Weihui Zhong
- Key Laboratory for Green Pharmaceutical Technologies and Related Equipment of Ministry of Education, College of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou 310014, People’s Republic of China
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30
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Abstract
Over the past few decades, manganese-catalyzed hydrosilylation of C=O or C=C/C≡C unsaturated bonds have undergone enormous developments. In this focus review, the hydrosilylation reactions of alkenes, alkynes, and carbonyl-containing substrates catalyzed by manganese complexes are summarized. Moreover, the mechanisms of the manganese-catalyzed hydrosilylation are briefly discussed.
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Affiliation(s)
- Xiaoxu Yang
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Congyang Wang
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
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31
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Hara N, Fujisawa S, Fujita M, Miyazawa M, Ochiai K, Katsuda S, Fujimoto T. Kinetic resolution of sterically hindered secondary alcohols catalyzed by aminophosphinite organocatalyst. Tetrahedron 2018. [DOI: 10.1016/j.tet.2017.11.062] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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32
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Yang X, Wang C. Dichotomy of Manganese Catalysis via Organometallic or Radical Mechanism: Stereodivergent Hydrosilylation of Alkynes. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201710206] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Xiaoxu Yang
- Beijing National Laboratory for Molecular Sciences; CAS Key Laboratory of Molecular Recognition and Function, CAS Research/Education Center for Excellence in Molecular Sciences; Institute of Chemistry; Chinese Academy of Sciences; Beijing 100190 China
- University of Chinese Academy of Sciences; Beijing 100049 China
| | - Congyang Wang
- Beijing National Laboratory for Molecular Sciences; CAS Key Laboratory of Molecular Recognition and Function, CAS Research/Education Center for Excellence in Molecular Sciences; Institute of Chemistry; Chinese Academy of Sciences; Beijing 100190 China
- University of Chinese Academy of Sciences; Beijing 100049 China
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33
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Yang X, Wang C. Dichotomy of Manganese Catalysis via Organometallic or Radical Mechanism: Stereodivergent Hydrosilylation of Alkynes. Angew Chem Int Ed Engl 2017; 57:923-928. [DOI: 10.1002/anie.201710206] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Indexed: 12/27/2022]
Affiliation(s)
- Xiaoxu Yang
- Beijing National Laboratory for Molecular Sciences; CAS Key Laboratory of Molecular Recognition and Function, CAS Research/Education Center for Excellence in Molecular Sciences; Institute of Chemistry; Chinese Academy of Sciences; Beijing 100190 China
- University of Chinese Academy of Sciences; Beijing 100049 China
| | - Congyang Wang
- Beijing National Laboratory for Molecular Sciences; CAS Key Laboratory of Molecular Recognition and Function, CAS Research/Education Center for Excellence in Molecular Sciences; Institute of Chemistry; Chinese Academy of Sciences; Beijing 100190 China
- University of Chinese Academy of Sciences; Beijing 100049 China
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34
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Abstract
In recent years, interest in homogeneous manganese catalyst development has intensified because of the earth-abundant and nontoxic nature of this metal. Although compounds of Mn have largely been utilized for epoxidation reactions, recent efforts have revealed that Mn catalysts can mediate a broad range of reductive transformations. Low-valent Mn compounds have proven to be particularly effective for the hydrosilylation of carbonyl- and carboxylate-containing substrates, and this Account aims to highlight my research group's contributions to this field. In our initial 2014 communication, we reported that the bis(imino)pyridine-supported compound (Ph2PPrPDI)Mn mediates ketone hydrosilylation with exceptional activity under solvent-free conditions. Silanes including Ph2SiH2, (EtO)3SiH, (EtO)2MeSiH, and (EtO)Me2SiH were found to partially reduce cyclohexanone in the presence of (Ph2PPrPDI)Mn, while turnover frequencies of up to 1280 min-1 were observed using PhSiH3. This led us to evaluate the hydrosilylation of 11 additional ketones and allowed for the atom-efficient preparation of tertiary and quaternary silanes. At that time, it was also discovered that (Ph2PPrPDI)Mn catalyzes the dihydrosilylation of esters (by way of acyl C-O bond hydrosilylation) to yield a mixture of silyl ethers with modest activity. Earlier this year, the scope of these transformations was extended to aldehydes and formates, and the observed hydrosilylation activities are among the highest obtained for any transition-metal catalyst. The effectiveness of three related catalysts has also been evaluated: (Ph2PPrPDI)MnH, (PyEtPDEA)Mn, and [(Ph2PEtPDI)Mn]2. To our surprise, (Ph2PPrPDI)MnH was found to exhibit higher carboxylate dihydrosilylation activity than (Ph2PPrPDI)Mn, while (PyEtPDEA)Mn demonstrated remarkable carbonyl hydrosilylation activity considering that it lacks a redox-active supporting ligand. The evaluation of [(Ph2PEtPDI)Mn]2 revealed competitive aldehyde hydrosilylation and formate dihydrosilylation turnover frequencies; however, this catalyst is significantly inhibited by pyridine and alkene donor groups. In our efforts to fully understand how (Ph2PPrPDI)Mn operates, a thorough electronic structure evaluation was conducted, and the ground-state doublet calculated for this compound was found to exhibit nonclassical features consistent with a low-spin Mn(II) center supported by a singlet PDI dianion and an intermediate-spin Mn(II) configuration featuring antiferromagnetic coupling to PDI diradical dianion. A comprehensive mechanistic investigation of (Ph2PPrPDI)Mn- and (Ph2PPrPDI)MnH-mediated hydrosilylation has revealed two operable pathways, a modified Ojima pathway that is more active for carbonyl hydrosilylation and an insertion pathway that is more effective for carboxylate reduction. Although these efforts represent a small fraction of the recent advances made in Mn catalysis, this work has proven to be influential for the development of Mn-based reduction catalysts and is likely to inform future efforts to develop Mn catalysts that can be used to prepare silicones.
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Affiliation(s)
- Ryan J. Trovitch
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
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