1
|
Booth R, Whitwood AC, Duhme-Klair AK. Effect of Ligand Substituents on Spectroscopic and Catalytic Properties of Water-Compatible Cp*Ir-(pyridinylmethyl)sulfonamide-Based Transfer Hydrogenation Catalysts. Inorg Chem 2024; 63:3815-3823. [PMID: 38343274 PMCID: PMC10900292 DOI: 10.1021/acs.inorgchem.3c04040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 01/23/2024] [Accepted: 01/30/2024] [Indexed: 02/27/2024]
Abstract
Transition-metal-based hydrogenation catalysts have applications ranging from high-value chemical synthesis to medicinal chemistry. A series of (pyridinylmethyl)sulfonamide ligands substituted with electron-withdrawing and -donating groups were synthesized to study the influence of the electronic contribution of the bidentate ligand in Cp*Ir piano-stool complexes. A variable-temperature NMR investigation revealed a strong correlation between the electron-donating ability of the substituent and the rate of stereoinversion of the complexes. This correlation was partially reflected in the catalytic activity of the corresponding catalysts. Complexes with electron-withdrawing substituents followed the trend observed in the variable-temperature NMR study, thereby confirming the rate-determining step to be donation of the hydride ligand. Strongly electron-donating groups, on the other hand, caused a change in the rate-determining step in the formation of the iridium-hydride species. These results demonstrate that the activity of these catalysts can be tuned systematically via changes in the electronic contribution of the bidentate (pyridinylmethyl)sulfonamide ligands.
Collapse
|
2
|
Taleb B, Jahjah R, Cornu D, Bechelany M, Al Ajami M, Kataya G, Hijazi A, El-Dakdouki MH. Exploring Hydrogen Sources in Catalytic Transfer Hydrogenation: A Review of Unsaturated Compound Reduction. Molecules 2023; 28:7541. [PMID: 38005261 PMCID: PMC10673347 DOI: 10.3390/molecules28227541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2023] [Revised: 11/06/2023] [Accepted: 11/07/2023] [Indexed: 11/26/2023] Open
Abstract
Catalytic transfer hydrogenation has emerged as a pivotal chemical process with transformative potential in various industries. This review highlights the significance of catalytic transfer hydrogenation, a reaction that facilitates the transfer of hydrogen from one molecule to another, using a distinct molecule as the hydrogen source in the presence of a catalyst. Unlike conventional direct hydrogenation, catalytic transfer hydrogenation offers numerous advantages, such as enhanced safety, cost-effective hydrogen donors, byproduct recyclability, catalyst accessibility, and the potential for catalytic asymmetric transfer hydrogenation, particularly with chiral ligands. Moreover, the diverse range of hydrogen donor molecules utilized in this reaction have been explored, shedding light on their unique properties and their impact on catalytic systems and the mechanism elucidation of some reactions. Alcohols such as methanol and isopropanol are prominent hydrogen donors, demonstrating remarkable efficacy in various reductions. Formic acid offers irreversible hydrogenation, preventing the occurrence of reverse reactions, and is extensively utilized in chiral compound synthesis. Unconventional donors such as 1,4-cyclohexadiene and glycerol have shown a good efficiency in reducing unsaturated compounds, with glycerol additionally serving as a green solvent in some transformations. The compatibility of these donors with various catalysts, substrates, and reaction conditions were all discussed. Furthermore, this paper outlines future trends which include the utilization of biomass-derived hydrogen donors, the exploration of hydrogen storage materials such as metal-organic frameworks (MOFs), catalyst development for enhanced activity and recyclability, and the utilization of eco-friendly solvents such as glycerol and ionic liquids. Innovative heating methods, diverse base materials, and continued research into catalyst-hydrogen donor interactions are aimed to shape the future of catalytic transfer hydrogenation, enhancing its selectivity and efficiency across various industries and applications.
Collapse
Affiliation(s)
- Batoul Taleb
- Platform for Research and Analysis in Environmental Sciences (PRASE), Doctoral School of Science and Technology, Lebanese University, Beirut P.O. Box 6573/14, Lebanon; (B.T.); (R.J.); (M.A.A.); (G.K.); (A.H.)
- Department of Chemistry, Faculty of Science, Beirut Arab University, Debbieh P.O. Box 11-5020, Lebanon
| | - Rabih Jahjah
- Platform for Research and Analysis in Environmental Sciences (PRASE), Doctoral School of Science and Technology, Lebanese University, Beirut P.O. Box 6573/14, Lebanon; (B.T.); (R.J.); (M.A.A.); (G.K.); (A.H.)
| | - David Cornu
- Institut Européen des Membranes (IEM), UMR 5635, University of Montpellier, ENSCM, CNRS, Place Eugène Bataillon, 34095 Montpellier, France;
| | - Mikhael Bechelany
- Institut Européen des Membranes (IEM), UMR 5635, University of Montpellier, ENSCM, CNRS, Place Eugène Bataillon, 34095 Montpellier, France;
- Applied Mathematics and Bioinformatics (CAMB), Gulf University for Science and Technology (GUST), Mubarak Al-Abdullah 32093, Kuwait
| | - Mohamad Al Ajami
- Platform for Research and Analysis in Environmental Sciences (PRASE), Doctoral School of Science and Technology, Lebanese University, Beirut P.O. Box 6573/14, Lebanon; (B.T.); (R.J.); (M.A.A.); (G.K.); (A.H.)
| | - Ghenwa Kataya
- Platform for Research and Analysis in Environmental Sciences (PRASE), Doctoral School of Science and Technology, Lebanese University, Beirut P.O. Box 6573/14, Lebanon; (B.T.); (R.J.); (M.A.A.); (G.K.); (A.H.)
- Institut Européen des Membranes (IEM), UMR 5635, University of Montpellier, ENSCM, CNRS, Place Eugène Bataillon, 34095 Montpellier, France;
| | - Akram Hijazi
- Platform for Research and Analysis in Environmental Sciences (PRASE), Doctoral School of Science and Technology, Lebanese University, Beirut P.O. Box 6573/14, Lebanon; (B.T.); (R.J.); (M.A.A.); (G.K.); (A.H.)
| | - Mohammad H. El-Dakdouki
- Department of Chemistry, Faculty of Science, Beirut Arab University, Debbieh P.O. Box 11-5020, Lebanon
| |
Collapse
|
3
|
Das TK, Rodriguez Treviño AM, Pandiri S, Irvankoski S, Siito-Nen JH, Rodriguez SM, Yousufuddin M, Kürti L. Catalyst-Free Transfer Hydrogenation of Activated Alkenes Exploiting Isopropanol as the Sole and Traceless Reductant. GREEN CHEMISTRY : AN INTERNATIONAL JOURNAL AND GREEN CHEMISTRY RESOURCE : GC 2023; 25:746-754. [PMID: 37637778 PMCID: PMC10457099 DOI: 10.1039/d2gc04315g] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/29/2023]
Abstract
Both metal-catalyzed and organocatalytic transfer hydrogenation reactions are widely employed for the reduction of C=O and C=N bonds. However, selective transfer hydrogenation reactions of C=C bonds remain challenging. Therefore, the chemoselective transfer hydrogenation of olefins under mild conditions and in the absence of metal catalysts, using readily available and inexpensive reducing agents (i.e. primary and secondary alcohols), will mark a significant advancement towards the development of green transfer hydrogenation strategies. Described herein is an unconventional catalyst-free transfer hydrogenation reaction of activated alkenes using isopropanol as an eco-friendly reductant and solvent. The reaction gives convenient synthetic access to a wide range of substituted malonic acid half oxyesters (SMAHOs) in moderate to good yields. Mechanistic investigations point towards an unprecedented hydrogen bond-assisted transfer hydrogenation process.
Collapse
Affiliation(s)
- Tamal Kanti Das
- Department of Chemistry, Rice University, Houston, Texas 77030, USA
| | | | - Sanjay Pandiri
- Department of Chemistry, Rice University, Houston, Texas 77030, USA
| | - Sini Irvankoski
- Department of Chemistry and Materials Science, Aalto University, FI-02150 Espoo, Finland
| | - Juha H Siito-Nen
- Department of Chemistry and Materials Science, Aalto University, FI-02150 Espoo, Finland
| | - Sara M Rodriguez
- Department of Natural Sciences, University of North Texas at Dallas, Dallas, Texas 75241, USA
| | - Muhammed Yousufuddin
- Department of Natural Sciences, University of North Texas at Dallas, Dallas, Texas 75241, USA
| | - László Kürti
- Department of Chemistry, Rice University, Houston, Texas 77030, USA
| |
Collapse
|
4
|
Kharitonov VB, Muratov DV, Loginov DA. Cyclopentadienyl complexes of group 9 metals in the total synthesis of natural products. Coord Chem Rev 2022. [DOI: 10.1016/j.ccr.2022.214744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
|
5
|
Bolitho EM, Worby NG, Coverdale JPC, Wolny JA, Schünemann V, Sadler PJ. Quinone Reduction by Organo-Osmium Half-Sandwich Transfer Hydrogenation Catalysts. Organometallics 2021. [DOI: 10.1021/acs.organomet.1c00358] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | - Nathan G. Worby
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, U.K
| | | | - Juliusz A. Wolny
- Fachbereich Physik, Technische Universität Kaiserslautern, Erwin-Schrödinger-Str. 46, D-67663 Kaiserslautern, Germany
| | - Volker Schünemann
- Fachbereich Physik, Technische Universität Kaiserslautern, Erwin-Schrödinger-Str. 46, D-67663 Kaiserslautern, Germany
| | - Peter J. Sadler
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, U.K
| |
Collapse
|
6
|
Asymmetric transfer hydrogenation of unsaturated ketones; factors influencing 1,4- vs 1,2- regio- and enantioselectivity, and alkene vs alkyne directing effects. Tetrahedron 2021. [DOI: 10.1016/j.tet.2020.131771] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
|
7
|
Shende V, Raut AB, Raghav P, Kelkar AA, Bhanage BM. Room-Temperature Asymmetric Transfer Hydrogenation of Biomass-Derived Levulinic Acid to Optically Pure γ-Valerolactone Using a Ruthenium Catalyst. ACS OMEGA 2019; 4:19491-19498. [PMID: 31763574 PMCID: PMC6868911 DOI: 10.1021/acsomega.9b03424] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 10/22/2019] [Indexed: 06/10/2023]
Abstract
This study presents a first report on ruthenium-catalyzed asymmetric transfer hydrogenation (ATH) of levulinic acid (LA) to chiral γ-valerolactone (GVL). ATH of LA has been explored with Noyori's chiral catalyst (Ru-TsDPEN) in methanol solvent. Efficacy of ATH reaction of LA was investigated under different reactions conditions such as temperature, catalyst, and hydrogen donor concentration. The effect of various organic tertiary bases along with formic acid (FA) as a hydrogen donor was studied, and N-methylpiperidine with FA (1:1 molar ratio) was revealed as an efficient hydrogen donor for ATH of LA to GVL furnishing chiral GVL with complete conversion and 93% enantiomeric excess (ee). This operationally simple and mild ATH protocol was tested for practical applicability of ATH of LA obtained from biomass waste (rice husk and wheat straw) and furnished chiral GVL with 82% ee.
Collapse
Affiliation(s)
- Vaishali
S. Shende
- Department
of Chemistry, Institute of Chemical Technology, Mumbai 400019, India
| | - Amol B. Raut
- Department
of Chemistry, Institute of Chemical Technology, Mumbai 400019, India
| | - Prathamesh Raghav
- Department
of Chemistry, Institute of Chemical Technology, Mumbai 400019, India
| | - Ashutosh A. Kelkar
- Chemical
Engineering and Process Development Division, CSIR-National Chemical Laboratory, Pune 411008, India
| | | |
Collapse
|
8
|
Li Y, Lei M, Yuan W, Meggers E, Gong L. An N-heterocyclic carbene iridium catalyst with metal-centered chirality for enantioselective transfer hydrogenation of imines. Chem Commun (Camb) 2018; 53:8089-8092. [PMID: 28677698 DOI: 10.1039/c7cc04691j] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
A cyclometalating N-heterocyclic carbene iridium complex featuring metal-centered chirality was designed and used for the asymmetric transfer hydrogenation (ATH) of imines. Four strongly σ-donating carbon-based substituents (2 carbenes and 2 phenyl moieties), a chirality transfer directly from the stereogenic metal center to the C[double bond, length as m-dash]N bond of substrates, as well as a restriction of catalyst deactivation by steric demanding substituents, render the new complex one of the most efficient catalysts for ATH of cyclic N-sulfonylimines (down to 0.01 mol% cat., 24 examples, 94-98% ee).
Collapse
Affiliation(s)
- Yanjun Li
- College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, People's Republic of China.
| | | | | | | | | |
Collapse
|
9
|
Yang F, Chen J, Shen G, Zhang X, Fan B. Asymmetric transfer hydrogenation reactions of N-sulfonylimines by using alcohols as hydrogen sources. Chem Commun (Camb) 2018; 54:4963-4966. [DOI: 10.1039/c8cc01284a] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A palladium/zinc co-catalytic system was established and successfully utilized in the asymmetric transfer hydrogenation reactions of N-sulfonylimines with alcohols as hydrogen sources.
Collapse
Affiliation(s)
- Fan Yang
- YMU-HKBU Joint Laboratory of Traditional Natural Medicine
- Yunnan Minzu University
- Kunming
- China
| | - Jingchao Chen
- YMU-HKBU Joint Laboratory of Traditional Natural Medicine
- Yunnan Minzu University
- Kunming
- China
| | - Guoli Shen
- YMU-HKBU Joint Laboratory of Traditional Natural Medicine
- Yunnan Minzu University
- Kunming
- China
| | - Xuexin Zhang
- YMU-HKBU Joint Laboratory of Traditional Natural Medicine
- Yunnan Minzu University
- Kunming
- China
| | - Baomin Fan
- YMU-HKBU Joint Laboratory of Traditional Natural Medicine
- Yunnan Minzu University
- Kunming
- China
- Key Laboratory of Chemistry in Ethnic Medicinal Resources
| |
Collapse
|
10
|
Shende VS, Singh P, Bhanage BM. Recent trends in organocatalyzed asymmetric reduction of prochiral ketones. Catal Sci Technol 2018. [DOI: 10.1039/c7cy02409f] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
This review depicts the recent practices followed in organocatalyzed asymmetric reduction of prochiral ketones, highlighting the main organocatalysts used for the past seven years.
Collapse
Affiliation(s)
- Vaishali S. Shende
- Department of Chemistry
- Institute of Chemical Technology
- Mumbai
- 400019 India
| | - Priya Singh
- Department of Chemistry
- Institute of Chemical Technology
- Mumbai
- 400019 India
| | | |
Collapse
|
11
|
Zhang Z, Butt NA, Zhang W. Asymmetric Hydrogenation of Nonaromatic Cyclic Substrates. Chem Rev 2016; 116:14769-14827. [DOI: 10.1021/acs.chemrev.6b00564] [Citation(s) in RCA: 224] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Zhenfeng Zhang
- School of Pharmacy and ‡School of Chemistry and Chemical
Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Nicholas A. Butt
- School of Pharmacy and ‡School of Chemistry and Chemical
Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Wanbin Zhang
- School of Pharmacy and ‡School of Chemistry and Chemical
Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| |
Collapse
|
12
|
Shende VS, Shingote SK, Deshpande SH, Kelkar AA. Asymmetric Transfer Hydrogenation of Cyclic Imines in Water with a Versatile Hydrogen Donor Formic Acid/N-Methylpiperidine: Rapid Access to Highly Enantioselective Amines. ChemistrySelect 2016. [DOI: 10.1002/slct.201600497] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Vaishali S. Shende
- Chemical Engineering and Process Development Division; CSIR-National Chemical Laboratory; Pune 411008 India
| | - Savita K. Shingote
- Chemical Engineering and Process Development Division; CSIR-National Chemical Laboratory; Pune 411008 India
| | - Sudhindra H. Deshpande
- Chemical Engineering and Process Development Division; CSIR-National Chemical Laboratory; Pune 411008 India
| | - Ashutosh. A. Kelkar
- Chemical Engineering and Process Development Division; CSIR-National Chemical Laboratory; Pune 411008 India
| |
Collapse
|
13
|
Wills M. Imino Transfer Hydrogenation Reductions. Top Curr Chem (Cham) 2016; 374:14. [DOI: 10.1007/s41061-016-0013-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 02/13/2016] [Indexed: 10/22/2022]
|
14
|
Foubelo F, Yus M. Catalytic Asymmetric Transfer Hydrogenation of Imines: Recent Advances. CHEM REC 2015; 15:907-24. [DOI: 10.1002/tcr.201500203] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Indexed: 11/06/2022]
Affiliation(s)
- Francisco Foubelo
- Departamento de Química Orgánica; Facultad de Ciencias and Centro de Innovación en Química Avanzada (ORFEO-CINQA); Universidad de Alicante; Apdo. 99 03080 Alicante Spain
| | - Miguel Yus
- Departamento de Química Orgánica; Facultad de Ciencias and Centro de Innovación en Química Avanzada (ORFEO-CINQA); Universidad de Alicante; Apdo. 99 03080 Alicante Spain
| |
Collapse
|
15
|
Yuan B, He R, Shen W, Huang C, Li M. Mechanistic Insights into the Cu(I)- and Cu(II)-Catalyzed Cyclization of o-Alkynylbenzaldehydes: The Solvent DMF and Oxidation State of Copper Affect the Reaction Mechanism. J Org Chem 2015; 80:6553-63. [DOI: 10.1021/acs.joc.5b00523] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Binfang Yuan
- Key Laboratory
of Luminescence
and Real-Time Analytical chemistry (Southwest University), Ministry
of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China
| | - Rongxing He
- Key Laboratory
of Luminescence
and Real-Time Analytical chemistry (Southwest University), Ministry
of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China
| | - Wei Shen
- Key Laboratory
of Luminescence
and Real-Time Analytical chemistry (Southwest University), Ministry
of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China
| | - Cheng Huang
- Key Laboratory
of Luminescence
and Real-Time Analytical chemistry (Southwest University), Ministry
of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China
| | - Ming Li
- Key Laboratory
of Luminescence
and Real-Time Analytical chemistry (Southwest University), Ministry
of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China
| |
Collapse
|
16
|
Shende VS, Deshpande SH, Shingote SK, Joseph A, Kelkar AA. Asymmetric Transfer Hydrogenation of Imines in Water by Varying the Ratio of Formic Acid to Triethylamine. Org Lett 2015; 17:2878-81. [PMID: 26023885 DOI: 10.1021/acs.orglett.5b00889] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Asymmetric transfer hydrogenation (ATH) of imines has been performed with variation in formic acid (F) and triethylamine (T) molar ratios in water. The F/T ratio is shown to affect both the reduction rate and enantioselectivity, with the optimum ratio being 1.1 in the ATH of imines with the Rh-(1S,2S)-TsDPEN catalyst. Use of methanol as a cosolvent enhanced reduction activity. A variety of imine substrates have been reduced, affording high yields (94-98%) and good to excellent enantioselectivities (89-98%). In comparison with the common azeotropic F-T system, the reduction with 1.1/1 F/T is faster.
Collapse
Affiliation(s)
- Vaishali S Shende
- Chemical Engineering and Process Development Division, CSIR-National Chemical Laboratory, Pune, India
| | - Sudhindra H Deshpande
- Chemical Engineering and Process Development Division, CSIR-National Chemical Laboratory, Pune, India
| | - Savita K Shingote
- Chemical Engineering and Process Development Division, CSIR-National Chemical Laboratory, Pune, India
| | - Anu Joseph
- Chemical Engineering and Process Development Division, CSIR-National Chemical Laboratory, Pune, India
| | - Ashutosh A Kelkar
- Chemical Engineering and Process Development Division, CSIR-National Chemical Laboratory, Pune, India
| |
Collapse
|
17
|
Pollice R, Dastbaravardeh N, Marquise N, Mihovilovic MD, Schnürch M. Mechanistic and Kinetic Studies of the Direct Alkylation of Benzylic Amines: A Formal C(sp 3)-H Activation Proceeds Actually via a C(sp 2)-H Activation Pathway. ACS Catal 2015; 5:587-595. [PMID: 25838971 PMCID: PMC4372103 DOI: 10.1021/cs501924c] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Indexed: 01/18/2023]
Abstract
Mechanistic investigations of a Rh(I)-catalyzed direct C-H alkylation of benzylic amines with alkenes, formally an C(sp3)-H activation, reveal this reaction to proceed via imine intermediates and, hence, via C(sp2)-H activation. The reaction shows a primary kinetic isotope effect of 4.3 at the benzylic C-H position together with a reversible H-D exchange at the same position, which indicates that there are at least two distinct steps in which the corresponding C-H bonds are broken. The imine intermediates are shown to be converted to the final product under the reaction conditions, and a time course analysis of the alkylated imine intermediate shows that it is formed before the final amine product in the course of the reaction.
Collapse
Affiliation(s)
- Robert Pollice
- Institute of Applied Synthetic
Chemistry, Vienna University of Technology, Getreidemarkt 9/163-OC, Vienna 1060, Austria
| | | | - Nada Marquise
- Institute of Applied Synthetic
Chemistry, Vienna University of Technology, Getreidemarkt 9/163-OC, Vienna 1060, Austria
| | - Marko D. Mihovilovic
- Institute of Applied Synthetic
Chemistry, Vienna University of Technology, Getreidemarkt 9/163-OC, Vienna 1060, Austria
| | - Michael Schnürch
- Institute of Applied Synthetic
Chemistry, Vienna University of Technology, Getreidemarkt 9/163-OC, Vienna 1060, Austria
| |
Collapse
|