101
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Hydrogenation and Transfer Hydrogenation Promoted by Tethered Ru−S Complexes: From Cooperative Dihydrogen Activation to Hydride Abstraction/Proton Release from Dihydrogen Surrogates. Chemistry 2016; 22:10009-16. [DOI: 10.1002/chem.201600386] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Indexed: 11/07/2022]
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102
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Li G, Kuo JL, Han A, Abuyuan JM, Young LC, Norton JR, Palmer JH. Radical Isomerization and Cycloisomerization Initiated by H• Transfer. J Am Chem Soc 2016; 138:7698-704. [PMID: 27167594 DOI: 10.1021/jacs.6b03509] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Under H2 pressure, Co(II)(dmgBF2)2L2 (L = H2O, THF) generates a low concentration of an H• donor. Transfer of the H• onto an olefin gives a radical that can either (1) transfer an H• back to the metal, generating an isomerized olefin, or (2) add intramolecularly to a double bond, generating a cyclized radical. Transfer of an H• back to the metal from the cyclized radical results in a cycloisomerization. Both outcomes are favored by the low concentration of the cobalt H• donor, whereas hydrogenation and cyclohydrogenation are more likely with other catalysts (when the concentration of the H• donor is high).
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Affiliation(s)
- Gang Li
- Department of Chemistry, Columbia University , 3000 Broadway, New York, New York 10027, United States
| | - Jonathan L Kuo
- Department of Chemistry, Columbia University , 3000 Broadway, New York, New York 10027, United States
| | - Arthur Han
- Department of Chemistry, Columbia University , 3000 Broadway, New York, New York 10027, United States
| | - Janine M Abuyuan
- Department of Chemistry, Barnard College , 3009 Broadway, New York, New York 10027, United States
| | - Lily C Young
- Department of Chemistry, Columbia University , 3000 Broadway, New York, New York 10027, United States
| | - Jack R Norton
- Department of Chemistry, Columbia University , 3000 Broadway, New York, New York 10027, United States
| | - Joshua H Palmer
- Department of Chemistry, Columbia University , 3000 Broadway, New York, New York 10027, United States
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103
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Miller DC, Tarantino KT, Knowles RR. Proton-Coupled Electron Transfer in Organic Synthesis: Fundamentals, Applications, and Opportunities. Top Curr Chem (Cham) 2016; 374:30. [PMID: 27573270 PMCID: PMC5107260 DOI: 10.1007/s41061-016-0030-6] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 04/21/2016] [Indexed: 10/21/2022]
Abstract
Proton-coupled electron transfers (PCETs) are unconventional redox processes in which both protons and electrons are exchanged, often in a concerted elementary step. While PCET is now recognized to play a central a role in biological redox catalysis and inorganic energy conversion technologies, its applications in organic synthesis are only beginning to be explored. In this chapter, we aim to highlight the origins, development, and evolution of the PCET processes most relevant to applications in organic synthesis. Particular emphasis is given to the ability of PCET to serve as a non-classical mechanism for homolytic bond activation that is complimentary to more traditional hydrogen atom transfer processes, enabling the direct generation of valuable organic radical intermediates directly from their native functional group precursors under comparatively mild catalytic conditions. The synthetically advantageous features of PCET reactivity are described in detail, along with examples from the literature describing the PCET activation of common organic functional groups.
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Affiliation(s)
- David C Miller
- Department of Chemistry, Princeton University, Princeton, NJ, 08544, USA
| | - Kyle T Tarantino
- Department of Chemistry, Princeton University, Princeton, NJ, 08544, USA
| | - Robert R Knowles
- Department of Chemistry, Princeton University, Princeton, NJ, 08544, USA.
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104
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Crossley SWM, Martinez RM, Guevara-Zuluaga S, Shenvi RA. Synthesis of the Privileged 8-Arylmenthol Class by Radical Arylation of Isopulegol. Org Lett 2016; 18:2620-3. [PMID: 27175746 DOI: 10.1021/acs.orglett.6b01047] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Hydrogen atom transfer (HAT) circumvents a disfavored Friedel-Crafts reaction in the derivatization of the inexpensive monoterpene isopulegol. A variety of readily prepared aryl and heteroaryl sulfonates undergo a formal hydroarylation to form 8-arylmenthols, privileged scaffolds for asymmetric synthesis, as typified by 8-phenylmenthol. High stereoselectivity is observed in related systems. This use of HAT significantly extends the chiral pool from the inexpensive monoterpene isopulegol.
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Affiliation(s)
- Steven W M Crossley
- Department of Chemistry, The Scripps Research Institute , 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Ruben M Martinez
- Department of Chemistry, The Scripps Research Institute , 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Sebastián Guevara-Zuluaga
- Department of Chemistry, The Scripps Research Institute , 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Ryan A Shenvi
- Department of Chemistry, The Scripps Research Institute , 10550 North Torrey Pines Road, La Jolla, California 92037, United States
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105
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Obradors C, Martinez RM, Shenvi RA. Ph(i-PrO)SiH2: An Exceptional Reductant for Metal-Catalyzed Hydrogen Atom Transfers. J Am Chem Soc 2016; 138:4962-71. [PMID: 26984323 PMCID: PMC4858193 DOI: 10.1021/jacs.6b02032] [Citation(s) in RCA: 192] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
We report the discovery of an outstanding reductant for metal-catalyzed radical hydrofunctionalization reactions. Observations of unexpected silane solvolysis distributions in the HAT-initiated hydrogenation of alkenes reveal that phenylsilane is not the kinetically preferred reductant in many of these transformations. Instead, isopropoxy(phenyl)silane forms under the reaction conditions, suggesting that alcohols function as important silane ligands to promote the formation of metal hydrides. Study of its reactivity showed that isopropoxy(phenyl)silane is an exceptionally efficient stoichiometric reductant, and it is now possible to significantly decrease catalyst loadings, lower reaction temperatures, broaden functional group tolerance, and use diverse, aprotic solvents in iron- and manganese-catalyzed hydrofunctionalizations. As representative examples, we have improved the yields and rates of alkene reduction, hydration, hydroamination, and conjugate addition. Discovery of this broadly applicable, chemoselective, and solvent-versatile reagent should allow an easier interface with existing radical reactions. Finally, isotope-labeling experiments rule out the alternative hypothesis of hydrogen atom transfer from a redox-active β-diketonate ligand in the HAT step. Instead, initial HAT from a metal hydride to directly generate a carbon-centered radical appears to be the most reasonable hypothesis.
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Affiliation(s)
- Carla Obradors
- Department of Chemistry, The Scripps Research Institute, La Jolla, California 92037, United States
| | - Ruben M. Martinez
- Department of Chemistry, The Scripps Research Institute, La Jolla, California 92037, United States
| | - Ryan A. Shenvi
- Department of Chemistry, The Scripps Research Institute, La Jolla, California 92037, United States
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106
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Nguyen LQ, Knowles RR. Catalytic C–N Bond-Forming Reactions Enabled by Proton-Coupled Electron Transfer Activation of Amide N–H Bonds. ACS Catal 2016. [DOI: 10.1021/acscatal.6b00486] [Citation(s) in RCA: 93] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Lucas Q. Nguyen
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Robert R. Knowles
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
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107
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Chung WJ, Vanderwal CD. Stereoselective Halogenation in Natural Product Synthesis. Angew Chem Int Ed Engl 2016; 55:4396-434. [PMID: 26833878 PMCID: PMC6028003 DOI: 10.1002/anie.201506388] [Citation(s) in RCA: 197] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Revised: 08/27/2015] [Indexed: 01/23/2023]
Abstract
At last count, nearly 5000 halogenated natural products have been discovered. In approximately half of these compounds, the carbon atom to which the halogen is bound is sp(3) -hybridized; therefore, there are an enormous number of natural products for which stereocontrolled halogenation must be a critical component of any synthesis strategy. In this Review, we critically discuss the methods and strategies used for stereoselective introduction of halogen atoms in the context of natural product synthesis. Using the successes of the past, we also attempt to identify gaps in our synthesis technology that would aid the synthesis of halogenated natural products, as well as existing methods that have not yet seen application in complex molecule synthesis. The chemistry described herein demonstrates yet again how natural products continue to provide the inspiration for critical advances in chemical synthesis.
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Affiliation(s)
- Won-jin Chung
- Department of Chemistry, Gwangju Institute of Science and Technology, Gwangju, South Korea.
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108
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Reyes JR, Rawal VH. Reductive Chlorination and Bromination of Ketones via Trityl Hydrazones. Angew Chem Int Ed Engl 2016; 55:3077-80. [PMID: 26823122 PMCID: PMC9078849 DOI: 10.1002/anie.201510909] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Indexed: 11/10/2022]
Abstract
A method is presented for the direct transformation of a ketone to the corresponding reduced alkyl chloride or bromide. The process involves the reaction of a ketone trityl hydrazone with tBuOCl to give a diazene which readily collapses to the α-chlorocarbinyl radical, reduction of which by a hydrogen atom source gives the alkyl chloride product. The use of N-bromosuccinimide provides the corresponding alkyl bromide. This unique transformation provides a reductive halogenation that complements Barton's redox-neutral vinyl halide synthesis.
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Affiliation(s)
- Julius R Reyes
- Department of Chemistry, The University of Chicago, 5735 South Ellis Avenue, Chicago, IL, 60637, USA
| | - Viresh H Rawal
- Department of Chemistry, The University of Chicago, 5735 South Ellis Avenue, Chicago, IL, 60637, USA.
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109
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Chung WJ, Vanderwal CD. Stereoselektive Halogenierungen in der Naturstoffsynthese. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201506388] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Won-jin Chung
- Department of Chemistry; Gwangju Institute of Science and Technology; Gwangju Südkorea
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110
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Reyes JR, Rawal VH. Reductive Chlorination and Bromination of Ketones via Trityl Hydrazones. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201510909] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Julius R. Reyes
- Department of Chemistry; The University of Chicago; 5735 South Ellis Avenue Chicago IL 60637 USA
| | - Viresh H. Rawal
- Department of Chemistry; The University of Chicago; 5735 South Ellis Avenue Chicago IL 60637 USA
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111
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Hoffmann RW. Markovnikov free radical addition reactions, a sleeping beauty kissed to life. Chem Soc Rev 2016; 45:577-83. [PMID: 26753913 DOI: 10.1039/c5cs00423c] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This review covers free radical additions, which are initiated by the formal addition of a hydrogen atom to a C[double bond, length as m-dash]C double bond. These reactions originated in the realms of inorganic chemistry, polymer chemistry, and organic chemistry, whereby barriers between these disciplines impeded the rapid implementation of the findings.
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Affiliation(s)
- Reinhard W Hoffmann
- Fachbereich Chemie der Philipps Universität Marburg, Hans Meerweinstr.4, D-35032 Marburg, Germany.
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112
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Prina Cerai G, Morandi B. Atom-economical cobalt-catalysed regioselective coupling of epoxides and aziridines with alkenes. Chem Commun (Camb) 2016; 52:9769-72. [DOI: 10.1039/c6cc04410g] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
An atom-economical cobalt-catalysed regioselective coupling of epoxides and aziridines with alkenes is reported.
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Affiliation(s)
| | - Bill Morandi
- Max-Planck-Institut für Kohlenforschung
- Mülheim an der Ruhr
- Germany
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113
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George DT, Kuenstner EJ, Pronin SV. A Concise Approach to Paxilline Indole Diterpenes. J Am Chem Soc 2015; 137:15410-3. [PMID: 26593869 DOI: 10.1021/jacs.5b11129] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
A synthetic approach to paxilline indole diterpenes is described. The route to the pentacyclic core relies on a new regioselective alkenylation of ketones and a tandem radical addition-aldol reaction sequence to access vicinal quaternary stereocenters. Emindole SB, the simplest member of the family, is synthesized in 11 steps from commercially available material to demonstrate the application of this approach.
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Affiliation(s)
- David T George
- Department of Chemistry, University of California , Irvine, California 92697-2025, United States
| | - Eric J Kuenstner
- Department of Chemistry, University of California , Irvine, California 92697-2025, United States
| | - Sergey V Pronin
- Department of Chemistry, University of California , Irvine, California 92697-2025, United States
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114
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Ma X, Herzon SB. Non-classical selectivities in the reduction of alkenes by cobalt-mediated hydrogen atom transfer. Chem Sci 2015; 6:6250-6255. [PMID: 30090243 PMCID: PMC6054054 DOI: 10.1039/c5sc02476e] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 08/19/2015] [Indexed: 11/21/2022] Open
Abstract
Classical methods for alkene hydrogenation typically reduce less-substituted or more-strained alkenes, or those in proximity to a directing group, most rapidly. Here we describe a cobalt-mediated hydrogenation protocol that provides complementary selectivities in the reduction of several classes of olefins and alkynes. The selectivity of this reduction derives from a hydrogen atom transfer mechanism, which favors the generation of the more stable alkylradical intermediate. We also report the first alkene hydrobromination, hydroiodination, and hydroselenylation by a hydrogen atom transfer process.
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Affiliation(s)
- Xiaoshen Ma
- Department of Chemistry , Yale University , New Haven , Connecticut 06520 , USA .
| | - Seth B Herzon
- Department of Chemistry , Yale University , New Haven , Connecticut 06520 , USA .
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115
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Bosch C, Fiser B, Gómez-Bengoa E, Bradshaw B, Bonjoch J. Approach to cis-Phlegmarine Alkaloids via Stereodivergent Reduction: Total Synthesis of (+)-Serratezomine E and Putative Structure of (-)-Huperzine N. Org Lett 2015; 17:5084-7. [PMID: 26406568 DOI: 10.1021/acs.orglett.5b02581] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A unified strategy for the synthesis of the cis-phlegmarine group of alkaloids is presented, leading to the first synthesis of serratezomine E (1) as well as the putative structure of huperzine N (2). A contrasteric hydrogenation method was developed based on the use of Wilkinson's catalyst, which allowed the facial selectivity of standard hydrogenation to be completely overturned. Calculations were performed to determine the mechanism, and structures for huperzines M and N are reassigned.
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Affiliation(s)
- Caroline Bosch
- Laboratori de Química Orgànica, Facultat de Farmàcia, IBUB, Universitat de Barcelona , Av. Joan XXIII s/n, 08028 Barcelona, Spain
| | - Béla Fiser
- Departamento de Química Orgánica I, Universidad del País Vasco , Manuel Lardizábal 3, 20018 San Sebastián, Spain
| | - Enrique Gómez-Bengoa
- Departamento de Química Orgánica I, Universidad del País Vasco , Manuel Lardizábal 3, 20018 San Sebastián, Spain
| | - Ben Bradshaw
- Laboratori de Química Orgànica, Facultat de Farmàcia, IBUB, Universitat de Barcelona , Av. Joan XXIII s/n, 08028 Barcelona, Spain
| | - Josep Bonjoch
- Laboratori de Química Orgànica, Facultat de Farmàcia, IBUB, Universitat de Barcelona , Av. Joan XXIII s/n, 08028 Barcelona, Spain
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116
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Abstract
![]()
A solution
to the classic unsolved problem of olefin hydromethylation
is presented. This highly chemoselective method can tolerate labile
and reactive chemical functionalities and uses a simple set of reagents.
An array of olefins, including mono-, di-, and trisubstituted olefins,
are all smoothly hydromethylated. This mild protocol can be used to
simplify the synthesis of a specific target or to directly “edit”
complex natural products and other advanced materials. The method
is also amenable to the simple installation of radioactive and stable
labeled methyl groups.
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Affiliation(s)
- Hai T Dao
- †Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Chao Li
- †Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Quentin Michaudel
- †Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Brad D Maxwell
- ‡Discovery Chemistry Platforms-Radiochemistry, Bristol-Myers Squibb, Route 206 and Province Line Road, Princeton, New Jersey 08543, United States
| | - Phil S Baran
- †Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
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117
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Affiliation(s)
- Dong Wang
- ISM, Université de Bordeaux, 351 Cours de la Libération, 33405 Talence Cedex, France
| | - Didier Astruc
- ISM, Université de Bordeaux, 351 Cours de la Libération, 33405 Talence Cedex, France
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118
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Gui J, Pan CM, Jin Y, Qin T, Lo JC, Lee BJ, Spergel SH, Mertzman ME, Pitts WJ, La Cruz TE, Schmidt MA, Darvatkar N, Natarajan SR, Baran PS. Practical olefin hydroamination with nitroarenes. Science 2015; 348:886-91. [DOI: 10.1126/science.aab0245] [Citation(s) in RCA: 313] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 04/07/2015] [Indexed: 12/24/2022]
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119
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Simonneau A, Oestreich M. Faszinierende Chemie des Wasserstoffatomtransfers auf Alkene inspiriert durch Probleme in Totalsynthesen. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201500557] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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120
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Simonneau A, Oestreich M. Fascinating hydrogen atom transfer chemistry of alkenes inspired by problems in total synthesis. Angew Chem Int Ed Engl 2015; 54:3556-8. [PMID: 25703197 DOI: 10.1002/anie.201500557] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Indexed: 11/12/2022]
Affiliation(s)
- Antoine Simonneau
- Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 115, 10623 Berlin (Germany) http://www.organometallics.tu-berlin.de
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121
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Kuo JL, Hartung J, Han A, Norton JR. Direct generation of oxygen-stabilized radicals by H• transfer from transition metal hydrides. J Am Chem Soc 2015; 137:1036-9. [PMID: 25569214 DOI: 10.1021/ja511883b] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Transition-metal hydrides generate α-alkoxy radicals by H• transfer to enol ethers. We have measured the rate constant for transfer from CpCr(CO)3H to n-butyl vinyl ether and have examined the chemistry of radicals generated by such transfers. Radicals from appropriate substrates undergo 5-exo cyclization, with higher diastereoselectivity than the analogous all-carbon radicals. From such radicals it is straightforward to make substituted tetrahydrofurans.
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Affiliation(s)
- Jonathan L Kuo
- Department of Chemistry, Columbia University , 3000 Broadway, New York, New York 10027, United States
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122
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Shigehisa H, Hiroya K. Markovnikov-selective Addition Reaction to Olefins Using Cobalt Complex. J SYN ORG CHEM JPN 2015. [DOI: 10.5059/yukigoseikyokaishi.73.788] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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123
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Lo JC, Gui J, Yabe Y, Pan CM, Baran PS. Functionalized olefin cross-coupling to construct carbon-carbon bonds. Nature 2014; 516:343-8. [PMID: 25519131 PMCID: PMC4271735 DOI: 10.1038/nature14006] [Citation(s) in RCA: 309] [Impact Index Per Article: 30.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2014] [Accepted: 10/20/2014] [Indexed: 12/23/2022]
Abstract
Carbon-carbon (C-C) bonds form the backbone of many important molecules, including polymers, dyes and pharmaceutical agents. The development of new methods to create these essential connections in a rapid and practical fashion has been the focus of numerous organic chemists. This endeavour relies heavily on the ability to form C-C bonds in the presence of sensitive functional groups and congested structural environments. Here we report a chemical transformation that allows the facile construction of highly substituted and uniquely functionalized C-C bonds. Using a simple iron catalyst, an inexpensive silane and a benign solvent under ambient atmosphere, heteroatom-substituted olefins are easily reacted with electron-deficient olefins to create molecular architectures that were previously difficult or impossible to access. More than 60 examples are presented with a wide array of substrates, demonstrating the chemoselectivity and mildness of this simple reaction.
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Affiliation(s)
- Julian C Lo
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
| | - Jinghan Gui
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
| | - Yuki Yabe
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
| | - Chung-Mao Pan
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
| | - Phil S Baran
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
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124
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Abstract
![]()
Catalytic amounts
of Co(SaltBu,tBu)Cl and
organosilane irreversibly isomerize terminal
alkenes by one position. The same catalysts effect cycloisomerization
of dienes and retrocycloisomerization of strained
rings. Strong Lewis bases like amines and imidazoles, and labile
functionalities like epoxides, are tolerated.
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Affiliation(s)
- Steven W M Crossley
- Department of Chemistry, The Scripps Research Institute , La Jolla, California 92037, United States
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125
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Michelet B, Bour C, Gandon V. Gallium-assisted transfer hydrogenation of alkenes. Chemistry 2014; 20:14488-92. [PMID: 25213294 DOI: 10.1002/chem.201404139] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Indexed: 11/08/2022]
Abstract
We report a rare case of alkene transfer hydrogenation using a main-group compound instead of a transition-metal complex as catalyst. We disclosed that 1,4-cyclohexadiene can be used as H2 surrogate towards olefin reduction in the presence of [IPrGaCl2 ][SbF6 ]. Hydrogenative cyclizations have also been carried out because this cationic gallium complex is also a potent hydroarylation catalyst.
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Affiliation(s)
- Bastien Michelet
- Université Paris-Sud, ICMMO (UMR CNRS 8182), LabEx CHARMAAAT, 91405 Orsay cedex (France), Fax: (+ 33)169154747, Homepage: www.polycata.u-psud.fr
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126
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King SM, Herzon SB. Substrate-modified functional group reactivity: hasubanan and acutumine alkaloid syntheses. J Org Chem 2014; 79:8937-47. [PMID: 25135456 DOI: 10.1021/jo501516x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Functional group taxonomy provides a powerful conceptual framework to classify and predict the chemical reactivity of molecular structures. These principals are most effective in monofunctional settings, wherein individual functional groups can be analyzed without complications. In more complex settings, the predictive value of these analyses decreases as alternative reaction pathways, promoted by neighboring substituents and aggregate molecular properties, emerge. We refer to this phenomenon as substrate-modified functional group reactivity. In this Perspective, we explain how substrate-modified functional group reactivity molded our synthetic routes to the hasubanan and acutumine alkaloids. These investigations underscore the potential for discovery and insight that can only be gained by studying the reactivity of complex multifunctional structures.
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Affiliation(s)
- Sandra M King
- Department of Chemistry, Yale University , New Haven, Connecticut 06520, United States
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