1
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Menchikov LG, Shulishov EV, Tomilov YV. Recent advances in the catalytic cyclopropanation of unsaturated compounds with diazomethane. RUSSIAN CHEMICAL REVIEWS 2021. [DOI: 10.1070/rcr4982] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The main achievements and development trends of the past 10–15 years related to the catalytic cyclopropanation of unsaturated compounds with diazomethane are integrated and analyzed. The attention is focused on the most efficient catalysts based on palladium compounds. Data on the effects of substrate structure and nature of catalyst components on the regio- and stereoselectivity of these reactions are systematized. Characteristic features of safe methods for diazomethane generation are considered, including the use of membrane technologies and continuous-flow and in situ preparation methods, which have prospects for industrial application.
The bibliography includes 281 references.
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2
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Sheeran JW, Campbell K, Breen CP, Hummel G, Huang C, Datta A, Boyer SH, Hecker SJ, Bio MM, Fang YQ, Ford DD, Russell MG. Scalable On-Demand Production of Purified Diazomethane Suitable for Sensitive Catalytic Reactions. Org Process Res Dev 2020. [DOI: 10.1021/acs.oprd.0c00485] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | | | | | - Gerald Hummel
- Snapdragon Chemistry, Waltham, Massachusetts 02451, United States
| | - Changfeng Huang
- Snapdragon Chemistry, Waltham, Massachusetts 02451, United States
| | - Anamika Datta
- Snapdragon Chemistry, Waltham, Massachusetts 02451, United States
| | - Serge H. Boyer
- Qpex Biopharma, Inc., San Diego, California 92121, United States
| | - Scott J. Hecker
- Qpex Biopharma, Inc., San Diego, California 92121, United States
| | - Matthew M. Bio
- Snapdragon Chemistry, Waltham, Massachusetts 02451, United States
| | - Yuan-Qing Fang
- Snapdragon Chemistry, Waltham, Massachusetts 02451, United States
| | - David D. Ford
- Snapdragon Chemistry, Waltham, Massachusetts 02451, United States
| | - M. Grace Russell
- Snapdragon Chemistry, Waltham, Massachusetts 02451, United States
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3
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Hone CA, Kappe CO. Membrane Microreactors for the On-Demand Generation, Separation, and Reaction of Gases. Chemistry 2020; 26:13108-13117. [PMID: 32515835 PMCID: PMC7692882 DOI: 10.1002/chem.202001942] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 06/08/2020] [Indexed: 11/25/2022]
Abstract
The use of gases as reagents in organic synthesis can be very challenging, particularly at a laboratory scale. This Concept takes into account recent studies to make the case that gases can indeed be efficiently and safely formed from relatively inexpensive commercially available reagents for use in a wide range of organic transformations. In particular, we argue that the exploitation of continuous flow membrane reactors enables the effective separation of the chemistry necessary for gas formation from the chemistry for gas consumption, with these two stages often containing incompatible chemistry. The approach outlined eliminates the need to store and transport excessive amounts of potentially toxic, reactive or explosive gases. The on‐demand generation, separation and reaction of a number of gases, including carbon monoxide, diazomethane, trifluoromethyl diazomethane, hydrogen cyanide, ammonia and formaldehyde, is discussed.
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Affiliation(s)
- Christopher A Hone
- Center for Continuous Flow Synthesis and Processing (CCFLOW), Research Center Pharmaceutical Engineering GmbH (RCPE), Inffeldgasse 13, 8010, Graz, Austria.,Institute of Chemistry, University of Graz, NAWI Graz, Heinrichstrasse 28, 8010, Graz, Austria
| | - C Oliver Kappe
- Center for Continuous Flow Synthesis and Processing (CCFLOW), Research Center Pharmaceutical Engineering GmbH (RCPE), Inffeldgasse 13, 8010, Graz, Austria.,Institute of Chemistry, University of Graz, NAWI Graz, Heinrichstrasse 28, 8010, Graz, Austria
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4
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Duan X, Huang Z, Qian G, He K, Zhang J, Mleczko L, Zhou X. Unprecedented yield of methyl-esterification with in-situ generated diazomethane in a microchannel reactor with methanol as solvent. Chem Eng Sci 2020. [DOI: 10.1016/j.ces.2019.115397] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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5
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Svec RL, Hergenrother PJ. Imidazotetrazines as Weighable Diazomethane Surrogates for Esterifications and Cyclopropanations. Angew Chem Int Ed Engl 2020; 59:1857-1862. [PMID: 31793158 DOI: 10.1002/anie.201911896] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 11/21/2019] [Indexed: 11/09/2022]
Abstract
Diazomethane is one of the most versatile reagents in organic synthesis, but its utility is limited by its hazardous nature. Although alternative methods exist to perform the unique chemistry of diazomethane, these suffer from diminished reactivity and/or correspondingly harsher conditions. Herein, we describe the repurposing of imidazotetrazines (such as temozolomide, TMZ, the standard of care for glioblastoma) for use as synthetic precursors of alkyl diazonium reagents. TMZ was employed to conduct esterifications and metal-catalyzed cyclopropanations, and results show that methyl ester formation from a wide variety of substrates is especially efficient and operationally simple. TMZ is a commercially available solid that is non-explosive and non-toxic, and should find broad utility as a replacement for diazomethane.
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Affiliation(s)
- Riley L Svec
- Department of Chemistry and Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Paul J Hergenrother
- Department of Chemistry and Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
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6
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Svec RL, Hergenrother PJ. Imidazotetrazines as Weighable Diazomethane Surrogates for Esterifications and Cyclopropanations. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201911896] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Riley L. Svec
- Department of Chemistry and Carl R. Woese Institute for Genomic BiologyUniversity of Illinois at Urbana-Champaign Urbana IL 61801 USA
| | - Paul J. Hergenrother
- Department of Chemistry and Carl R. Woese Institute for Genomic BiologyUniversity of Illinois at Urbana-Champaign Urbana IL 61801 USA
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7
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Green SP, Wheelhouse KM, Payne AD, Hallett JP, Miller PW, Bull JA. Thermal Stability and Explosive Hazard Assessment of Diazo Compounds and Diazo Transfer Reagents. Org Process Res Dev 2019; 24:67-84. [PMID: 31983869 PMCID: PMC6972035 DOI: 10.1021/acs.oprd.9b00422] [Citation(s) in RCA: 109] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Indexed: 11/29/2022]
Abstract
Despite their wide use in academia as metal-carbene precursors, diazo compounds are often avoided in industry owing to concerns over their instability, exothermic decomposition, and potential explosive behavior. The stability of sulfonyl azides and other diazo transfer reagents is relatively well understood, but there is little reliable data available for diazo compounds. This work first collates available sensitivity and thermal analysis data for diazo transfer reagents and diazo compounds to act as an accessible reference resource. Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and accelerating rate calorimetry (ARC) data for the model donor/acceptor diazo compound ethyl (phenyl)diazoacetate are presented. We also present a rigorous DSC dataset with 43 other diazo compounds, enabling direct comparison to other energetic materials to provide a clear reference work to the academic and industrial chemistry communities. Interestingly, there is a wide range of onset temperatures (T onset) for this series of compounds, which varied between 75 and 160 °C. The thermal stability variation depends on the electronic effect of substituents and the amount of charge delocalization. A statistical model is demonstrated to predict the thermal stability of differently substituted phenyl diazoacetates. A maximum recommended process temperature (T D24) to avoid decomposition is estimated for selected diazo compounds. The average enthalpy of decomposition (ΔH D) for diazo compounds without other energetic functional groups is -102 kJ mol-1. Several diazo transfer reagents are analyzed using the same DSC protocol and found to have higher thermal stability, which is in general agreement with the reported values. For sulfonyl azide reagents, an average ΔH D of -201 kJ mol-1 is observed. High-quality thermal data from ARC experiments shows the initiation of decomposition for ethyl (phenyl)diazoacetate to be 60 °C, compared to that of 100 °C for the common diazo transfer reagent p-acetamidobenzenesulfonyl azide (p-ABSA). The Yoshida correlation is applied to DSC data for each diazo compound to provide an indication of both their impact sensitivity (IS) and explosivity. As a neat substance, none of the diazo compounds tested are predicted to be explosive, but many (particularly donor/acceptor diazo compounds) are predicted to be impact-sensitive. It is therefore recommended that manipulation, agitation, and other processing of neat diazo compounds are conducted with due care to avoid impacts, particularly in large quantities. The full dataset is presented to inform chemists of the nature and magnitude of hazards when using diazo compounds and diazo transfer reagents. Given the demonstrated potential for rapid heat generation and gas evolution, adequate temperature control and cautious addition of reagents that begin a reaction are strongly recommended when conducting reactions with diazo compounds.
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Affiliation(s)
- Sebastian P Green
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, 80 Wood Lane, London W12 0BZ, U.K.,Department of Chemical Engineering, Imperial College London, South Kensington Campus, Exhibition Road, London SW7 2AZ, U.K
| | - Katherine M Wheelhouse
- API Chemistry, Product Development & Supply and Process Safety, Pilot Plant Operations, GlaxoSmithKline, GSK Medicines Research Centre, Gunnels Wood Road, Stevenage, Hertfordshire SG1 2NY, U.K
| | - Andrew D Payne
- API Chemistry, Product Development & Supply and Process Safety, Pilot Plant Operations, GlaxoSmithKline, GSK Medicines Research Centre, Gunnels Wood Road, Stevenage, Hertfordshire SG1 2NY, U.K
| | - Jason P Hallett
- Department of Chemical Engineering, Imperial College London, South Kensington Campus, Exhibition Road, London SW7 2AZ, U.K
| | - Philip W Miller
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, 80 Wood Lane, London W12 0BZ, U.K
| | - James A Bull
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, 80 Wood Lane, London W12 0BZ, U.K
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8
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9
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Zheng X, Zeng J, Xiong M, Huang J, Li C, Zhou R, Xiao D. Methyl Trifluoroacetate as a Methylation Reagent for N−H, O−H, and S−H Functionalities under Mild Conditions. ASIAN J ORG CHEM 2019. [DOI: 10.1002/ajoc.201900413] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Xin Zheng
- College of ChemistryGuangdong University of Petrochemical Technology Maoming 525000 P. R. China
| | - Jiechun Zeng
- College of ChemistryGuangdong University of Petrochemical Technology Maoming 525000 P. R. China
| | - Mindong Xiong
- College of ChemistryGuangdong University of Petrochemical Technology Maoming 525000 P. R. China
| | - Jiawei Huang
- College of ChemistryGuangdong University of Petrochemical Technology Maoming 525000 P. R. China
| | - Cuiyan Li
- College of ChemistryGuangdong University of Petrochemical Technology Maoming 525000 P. R. China
| | - Rujin Zhou
- College of ChemistryGuangdong University of Petrochemical Technology Maoming 525000 P. R. China
| | - Duoduo Xiao
- College of ChemistryGuangdong University of Petrochemical Technology Maoming 525000 P. R. China
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10
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Wernik M, Poechlauer P, Schmoelzer C, Dallinger D, Kappe CO. Design and Optimization of a Continuous Stirred Tank Reactor Cascade for Membrane-Based Diazomethane Production: Synthesis of α-Chloroketones. Org Process Res Dev 2019. [DOI: 10.1021/acs.oprd.9b00115] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Michaela Wernik
- Center for Continuous Flow Synthesis and Processing (CCFLOW), Research Center Pharmaceutical Engineering GmbH (RCPE), Inffeldgasse 13, 8010 Graz, Austria
- Institute of Chemistry, University of Graz, NAWI Graz, Heinrichstrasse 28, 8010 Graz, Austria
| | - Peter Poechlauer
- Patheon Austria GmbH & Co KG, Sankt-Peter-Straße 25, 4020 Linz, Austria
| | | | - Doris Dallinger
- Center for Continuous Flow Synthesis and Processing (CCFLOW), Research Center Pharmaceutical Engineering GmbH (RCPE), Inffeldgasse 13, 8010 Graz, Austria
- Institute of Chemistry, University of Graz, NAWI Graz, Heinrichstrasse 28, 8010 Graz, Austria
| | - C. Oliver Kappe
- Center for Continuous Flow Synthesis and Processing (CCFLOW), Research Center Pharmaceutical Engineering GmbH (RCPE), Inffeldgasse 13, 8010 Graz, Austria
- Institute of Chemistry, University of Graz, NAWI Graz, Heinrichstrasse 28, 8010 Graz, Austria
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11
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Chen Y, Leonardi M, Dingwall P, Labes R, Pasau P, Blakemore DC, Ley SV. Photochemical Homologation for the Preparation of Aliphatic Aldehydes in Flow. J Org Chem 2018; 83:15558-15568. [DOI: 10.1021/acs.joc.8b02721] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yiding Chen
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K
| | - Marco Leonardi
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K
- Departmento de Química en Ciencias Farmacéuticas, Facultad de Farmacia, Universidad Complutense, 28040 Madrid, Spain
| | - Paul Dingwall
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K
| | - Ricardo Labes
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K
| | - Patrick Pasau
- UCB Biopharma SPRL, Chemical Research R5, Chemin du Foriest, 1420 Braine-L’Alleud, Belgium
| | - David C. Blakemore
- Medicine Design, Pfizer, Inc., Eastern Point Road, Groton, Connecticut 06340, United States
| | - Steven V. Ley
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K
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12
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Hock KJ, Koenigs RM. The Generation of Diazo Compounds in Continuous-Flow. Chemistry 2018; 24:10571-10583. [PMID: 29575129 DOI: 10.1002/chem.201800136] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 03/13/2018] [Indexed: 01/19/2023]
Abstract
Toxic, cancerogenic and explosive-these attributes are typically associated with diazo compounds. Nonetheless, diazo compounds are nowadays a highly demanded class of reagents for organic synthesis, yet the concerns with regards to safe and scalable transformations of these compounds are still exceptionally high. Lately, the research area of the continuous-flow synthesis of diazo compounds attracted significant interest and a whole variety of protocols for their "on-demand" preparation have been realized to date. This concept article focuses on the recent developments using continuous-flow technologies to access diazo compounds; thus minimizing risks and hazards when working with this particular class of compounds. In this article we discuss these concepts and highlight different pre-requisites to access and to perform downstream functionalization reaction.
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Affiliation(s)
- Katharina J Hock
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074, Aachen, Germany
| | - Rene M Koenigs
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074, Aachen, Germany
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13
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Rullière P, Benoit G, Allouche EMD, Charette AB. Safe and Facile Access to Nonstabilized Diazoalkanes Using Continuous Flow Technology. Angew Chem Int Ed Engl 2018; 57:5777-5782. [DOI: 10.1002/anie.201802092] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Indexed: 11/07/2022]
Affiliation(s)
- Pauline Rullière
- Faculty of Arts and Sciences; Department of Chemistry; Université de Montreal; P.O. Box 6128 Station Downtown Montreal Quebec H3C 3J7 Canada
| | - Guillaume Benoit
- Faculty of Arts and Sciences; Department of Chemistry; Université de Montreal; P.O. Box 6128 Station Downtown Montreal Quebec H3C 3J7 Canada
| | - Emmanuelle M. D. Allouche
- Faculty of Arts and Sciences; Department of Chemistry; Université de Montreal; P.O. Box 6128 Station Downtown Montreal Quebec H3C 3J7 Canada
| | - André B. Charette
- Faculty of Arts and Sciences; Department of Chemistry; Université de Montreal; P.O. Box 6128 Station Downtown Montreal Quebec H3C 3J7 Canada
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14
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Rullière P, Benoit G, Allouche EMD, Charette AB. Safe and Facile Access to Nonstabilized Diazoalkanes Using Continuous Flow Technology. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201802092] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Pauline Rullière
- Faculty of Arts and Sciences; Department of Chemistry; Université de Montreal; P.O. Box 6128 Station Downtown Montreal Quebec H3C 3J7 Canada
| | - Guillaume Benoit
- Faculty of Arts and Sciences; Department of Chemistry; Université de Montreal; P.O. Box 6128 Station Downtown Montreal Quebec H3C 3J7 Canada
| | - Emmanuelle M. D. Allouche
- Faculty of Arts and Sciences; Department of Chemistry; Université de Montreal; P.O. Box 6128 Station Downtown Montreal Quebec H3C 3J7 Canada
| | - André B. Charette
- Faculty of Arts and Sciences; Department of Chemistry; Université de Montreal; P.O. Box 6128 Station Downtown Montreal Quebec H3C 3J7 Canada
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15
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BURTOLOSO ANTONIOC, MOMO PATRÍCIAB, NOVAIS GRAZIELEL. Traditional and New methods for the Preparation of Diazocarbonyl Compounds. ACTA ACUST UNITED AC 2018; 90:859-893. [DOI: 10.1590/0001-3765201820170768] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Accepted: 11/16/2017] [Indexed: 12/14/2022]
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16
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Yang H, Martin B, Schenkel B. On-Demand Generation and Consumption of Diazomethane in Multistep Continuous Flow Systems. Org Process Res Dev 2018. [DOI: 10.1021/acs.oprd.7b00302] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Hongwei Yang
- Chemical and Analytical Development, Suzhou Novartis Pharma Technology Company Limited, 18 Tonglian Road, Changshu, Jiangsu 215537, China
| | - Benjamin Martin
- Chemical and Analytical Development, Novartis Pharma AG, Fabrikstrasse, 4002 Basel, Switzerland
| | - Berthold Schenkel
- Chemical and Analytical Development, Novartis Pharma AG, Fabrikstrasse, 4002 Basel, Switzerland
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17
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Dingwall P, Greb A, Crespin LNS, Labes R, Musio B, Poh JS, Pasau P, Blakemore DC, Ley SV. C–H functionalisation of aldehydes using light generated, non-stabilised diazo compounds in flow. Chem Commun (Camb) 2018; 54:11685-11688. [DOI: 10.1039/c8cc06202a] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Here we explore further the use of oxadiazolines, non-stabilised diazo precursors which are bench stable, in direct, non-catalytic, aldehyde C–H functionalisation reactions under UV photolysis in flow and free from additives.
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Affiliation(s)
- Paul Dingwall
- Department of Chemistry
- University of Cambridge
- Lensfield Road
- Cambridge CB2 1EW
- UK
| | - Andreas Greb
- Department of Chemistry
- University of Cambridge
- Lensfield Road
- Cambridge CB2 1EW
- UK
| | | | - Ricardo Labes
- Department of Chemistry
- University of Cambridge
- Lensfield Road
- Cambridge CB2 1EW
- UK
| | - Biagia Musio
- Department of Chemistry
- University of Cambridge
- Lensfield Road
- Cambridge CB2 1EW
- UK
| | - Jian-Siang Poh
- Department of Chemistry
- University of Cambridge
- Lensfield Road
- Cambridge CB2 1EW
- UK
| | | | | | - Steven V. Ley
- Department of Chemistry
- University of Cambridge
- Lensfield Road
- Cambridge CB2 1EW
- UK
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18
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Empel C, Hock KJ, Koenigs RM. Iron-catalysed carbene-transfer reactions of diazo acetonitrile. Org Biomol Chem 2018; 16:7129-7133. [DOI: 10.1039/c8ob01991f] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Herein we report the flow synthesis of hazardous diazo acetonitrile to enable X–H insertion reactions with a readily available iron catalyst.
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Affiliation(s)
- Claire Empel
- RWTH Aachen University
- Institute of Organic Chemistry
- D-52074 Aachen
- Germany
| | - Katharina J. Hock
- RWTH Aachen University
- Institute of Organic Chemistry
- D-52074 Aachen
- Germany
| | - Rene M. Koenigs
- RWTH Aachen University
- Institute of Organic Chemistry
- D-52074 Aachen
- Germany
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19
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Penverne C, Hazard B, Rolando C, Penhoat M. Scale-up Study of Benzoic Acid Alkylation in Flow: From Microflow Capillary Reactor to a Milliflow Reactor. Org Process Res Dev 2017. [DOI: 10.1021/acs.oprd.7b00246] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Christophe Penverne
- USR 3290, MSAP, Miniaturisation
pour la Synthèse l’Analyse et la Protéomique,
and FR 2638, Institut Eugène-Michel Chevreul, Université de Lille, F-59000 Lille, France
| | - Benjamin Hazard
- USR 3290, MSAP, Miniaturisation
pour la Synthèse l’Analyse et la Protéomique,
and FR 2638, Institut Eugène-Michel Chevreul, Université de Lille, F-59000 Lille, France
| | - Christian Rolando
- USR 3290, MSAP, Miniaturisation
pour la Synthèse l’Analyse et la Protéomique,
and FR 2638, Institut Eugène-Michel Chevreul, Université de Lille, F-59000 Lille, France
| | - Maël Penhoat
- USR 3290, MSAP, Miniaturisation
pour la Synthèse l’Analyse et la Protéomique,
and FR 2638, Institut Eugène-Michel Chevreul, Université de Lille, F-59000 Lille, France
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20
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Dallinger D, Kappe CO. Lab-scale production of anhydrous diazomethane using membrane separation technology. Nat Protoc 2017; 12:2138-2147. [PMID: 28906494 DOI: 10.1038/nprot.2017.046] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Diazomethane is among the most versatile and useful reagents for introducing methyl or methylene groups in organic synthesis. However, because of its explosive nature, its generation and purification by distillation are accompanied by a certain safety risk. This protocol describes how to construct a configurationally simple tube-in-flask reactor for the in situ on-demand generation of anhydrous diazomethane using membrane separation technology and thus avoiding distillation methods. The described reactor can be prepared from commercially available parts within ∼1 h. In this system, solutions of Diazald and aqueous potassium hydroxide are continuously pumped into a spiral of membrane tubing, and diazomethane is generated upon mixing of the two streams. Pure diazomethane gas diffuses out of the reaction mixture through the membrane tubing (made of gas-permeable Teflon AF-2400). As the membrane tubing is immersed in a flask filled with the substrate solution, diazomethane is instantly consumed, which minimizes the risk of diazomethane accumulation. For this protocol, the reaction of diazomethane with benzoic acid on a 5-mmol scale has been selected as a model reaction and is described in detail. Methyl benzoate was isolated in an 88-90% yield (597-611 mg) within ∼3 h.
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Affiliation(s)
- Doris Dallinger
- Institute of Chemistry, University of Graz, NAWI Graz, Graz, Austria
| | - C Oliver Kappe
- Institute of Chemistry, University of Graz, NAWI Graz, Graz, Austria.,Research Center Pharmaceutical Engineering GmbH (RCPE), Graz, Austria
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21
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Audubert C, Lebel H. Mild Esterification of Carboxylic Acids via Continuous Flow Diazotization of Amines. Org Lett 2017; 19:4407-4410. [DOI: 10.1021/acs.orglett.7b02231] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Clément Audubert
- Département de Chimie,
Center for Green Chemistry and Catalysis, Université de Montréal, C.P. 6128, Succursale Centre-ville, Montréal, Québec, Canada H3C 3J7
| | - Hélène Lebel
- Département de Chimie,
Center for Green Chemistry and Catalysis, Université de Montréal, C.P. 6128, Succursale Centre-ville, Montréal, Québec, Canada H3C 3J7
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22
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Plutschack MB, Pieber B, Gilmore K, Seeberger PH. The Hitchhiker's Guide to Flow Chemistry ∥. Chem Rev 2017; 117:11796-11893. [PMID: 28570059 DOI: 10.1021/acs.chemrev.7b00183] [Citation(s) in RCA: 1020] [Impact Index Per Article: 145.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Flow chemistry involves the use of channels or tubing to conduct a reaction in a continuous stream rather than in a flask. Flow equipment provides chemists with unique control over reaction parameters enhancing reactivity or in some cases enabling new reactions. This relatively young technology has received a remarkable amount of attention in the past decade with many reports on what can be done in flow. Until recently, however, the question, "Should we do this in flow?" has merely been an afterthought. This review introduces readers to the basic principles and fundamentals of flow chemistry and critically discusses recent flow chemistry accounts.
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Affiliation(s)
- Matthew B Plutschack
- Department of Biomolecular Systems, Max-Planck Institute of Colloids and Interfaces , Am Mühlenberg 1, 14476 Potsdam, Germany
| | - Bartholomäus Pieber
- Department of Biomolecular Systems, Max-Planck Institute of Colloids and Interfaces , Am Mühlenberg 1, 14476 Potsdam, Germany
| | - Kerry Gilmore
- Department of Biomolecular Systems, Max-Planck Institute of Colloids and Interfaces , Am Mühlenberg 1, 14476 Potsdam, Germany
| | - Peter H Seeberger
- Department of Biomolecular Systems, Max-Planck Institute of Colloids and Interfaces , Am Mühlenberg 1, 14476 Potsdam, Germany.,Institute of Chemistry and Biochemistry, Department of Biology, Chemistry and Pharmacy, Freie Universität Berlin , Arnimallee 22, 14195 Berlin, Germany
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23
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Audubert C, Gamboa Marin OJ, Lebel H. Batch and Continuous-Flow One-Pot Processes using Amine Diazotization to Produce Silylated Diazo Reagents. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201612235] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
| | | | - Hélène Lebel
- Département de chimie; Université de Montréal; Canada
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24
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Audubert C, Gamboa Marin OJ, Lebel H. Batch and Continuous-Flow One-Pot Processes using Amine Diazotization to Produce Silylated Diazo Reagents. Angew Chem Int Ed Engl 2017; 56:6294-6297. [DOI: 10.1002/anie.201612235] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Indexed: 12/23/2022]
Affiliation(s)
| | | | - Hélène Lebel
- Département de chimie; Université de Montréal; Canada
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25
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Zhang Z, Li Y, He H, Qian X, Yang Y. Mild Chemotriggered Generation of a Fluorophore-Tethered Diazoalkane Species via Smiles Rearrangement. Org Lett 2016; 18:4674-7. [DOI: 10.1021/acs.orglett.6b02303] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Ziqian Zhang
- Division
of Health Toxicology and Function Test, Guangxi Center for Disease Prevention and Control, Nanning 530021, China
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26
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Movsisyan M, Delbeke EIP, Berton JKET, Battilocchio C, Ley SV, Stevens CV. Taming hazardous chemistry by continuous flow technology. Chem Soc Rev 2016; 45:4892-928. [PMID: 27453961 DOI: 10.1039/c5cs00902b] [Citation(s) in RCA: 390] [Impact Index Per Article: 48.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Over the last two decades, flow technologies have become increasingly popular in the field of organic chemistry, offering solutions for engineering and/or chemical problems. Flow reactors enhance the mass and heat transfer, resulting in rapid reaction mixing, and enable a precise control over the reaction parameters, increasing the overall process selectivity, efficiency and safety. These features allow chemists to tackle unexploited challenges in their work, with the ultimate objective making chemistry more accessible for laboratory and industrial applications, avoiding the need to store and handle toxic, reactive and explosive reagents. This review covers some of the latest and most relevant developments in the field of continuous flow chemistry with the focus on hazardous reactions.
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Affiliation(s)
- M Movsisyan
- SynBioC, Department of Sustainable Organic Chemistry and Technology, Ghent University, Coupure Links 653, 9000 Ghent, Belgium.
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27
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Singh R, Lee HJ, Singh AK, Kim DP. Recent advances for serial processes of hazardous chemicals in fully integrated microfluidic systems. KOREAN J CHEM ENG 2016. [DOI: 10.1007/s11814-016-0114-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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28
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Pieber B, Kappe CO. Generation and Synthetic Application of Trifluoromethyl Diazomethane Utilizing Continuous Flow Technologies. Org Lett 2016; 18:1076-9. [PMID: 26902154 DOI: 10.1021/acs.orglett.6b00194] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
A continuous process for the synthesis and inline separation of anhydrous trifluoromethyl diazomethane in a single continuous flow process is presented. The diazo building block is generated from the corresponding amine and NaNO2 under acidic, aqueous conditions and subsequently diffuses through a gas-permeable membrane into an organic stream. To avoid storage and transportation of the hazardous compound, a representative downstream process in a packed-bed reactor yielding highly functionalized building blocks was developed.
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Affiliation(s)
- Bartholomäus Pieber
- Institute of Chemistry, University of Graz , NAWI Graz, Heinrichstrasse 28, A-8010 Graz, Austria
| | - C Oliver Kappe
- Institute of Chemistry, University of Graz , NAWI Graz, Heinrichstrasse 28, A-8010 Graz, Austria
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29
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Westermann T, Mleczko L. Heat Management in Microreactors for Fast Exothermic Organic Syntheses—First Design Principles. Org Process Res Dev 2015. [DOI: 10.1021/acs.oprd.5b00205] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | - Leslaw Mleczko
- Bayer
Technology Services GmbH, 51368 Leverkusen, Germany
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30
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Müller STR, Murat A, Hellier P, Wirth T. Toward a Large-Scale Approach to Milnacipran Analogues Using Diazo Compounds in Flow Chemistry. Org Process Res Dev 2015. [DOI: 10.1021/acs.oprd.5b00308] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Simon T. R. Müller
- School
of Chemistry, Cardiff University, Park Place, Cardiff CF10 3AT, U.K
| | - Aurélien Murat
- Institut de Recherche Pierre Fabre, 81603 Gaillac, France
| | - Paul Hellier
- Pierre Fabre Médicament, Parc Industriel de la Chartreuse, 81106 Castres, France
| | - Thomas Wirth
- School
of Chemistry, Cardiff University, Park Place, Cardiff CF10 3AT, U.K
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31
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Ford A, Miel H, Ring A, Slattery CN, Maguire AR, McKervey MA. Modern Organic Synthesis with α-Diazocarbonyl Compounds. Chem Rev 2015; 115:9981-10080. [PMID: 26284754 DOI: 10.1021/acs.chemrev.5b00121] [Citation(s) in RCA: 1090] [Impact Index Per Article: 121.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
| | - Hugues Miel
- Almac Discovery Ltd. , David Keir Building, Stranmillis Road, Belfast BT9 5AG, United Kingdom
| | | | | | | | - M Anthony McKervey
- Almac Sciences Ltd. , Almac House, 20 Seagoe Industrial Estate, Craigavon BT63 5QD, United Kingdom
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32
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Wu KJ, Nappo V, Kuhn S. Hydrodynamic Study of Single- and Two-Phase Flow in an Advanced-Flow Reactor. Ind Eng Chem Res 2015. [DOI: 10.1021/acs.iecr.5b01444] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ke-Jun Wu
- Department
of Chemical Engineering, University College London, Torrington Place, London WC1E 7JE, U.K
| | - Valentina Nappo
- Department
of Chemical Engineering, University College London, Torrington Place, London WC1E 7JE, U.K
| | - Simon Kuhn
- Department
of Chemical Engineering, University College London, Torrington Place, London WC1E 7JE, U.K
- Department
of Chemical Engineering, KU Leuven, W. de Croylaan 46, 3001 Leuven, Belgium
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33
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Nieves-Remacha MJ, Kulkarni AA, Jensen KF. OpenFOAM Computational Fluid Dynamic Simulations of Single-Phase Flows in an Advanced-Flow Reactor. Ind Eng Chem Res 2015. [DOI: 10.1021/acs.iecr.5b00232] [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)
- María José Nieves-Remacha
- Department
of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Amol A. Kulkarni
- Department
of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- CEPD, CSIR-National Chemical Laboratory, Pune 411008, India
| | - Klavs F. Jensen
- Department
of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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34
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Baumann M, Baxendale IR. The synthesis of active pharmaceutical ingredients (APIs) using continuous flow chemistry. Beilstein J Org Chem 2015; 11:1194-219. [PMID: 26425178 PMCID: PMC4578405 DOI: 10.3762/bjoc.11.134] [Citation(s) in RCA: 252] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Accepted: 07/06/2015] [Indexed: 12/23/2022] Open
Abstract
The implementation of continuous flow processing as a key enabling technology has transformed the way we conduct chemistry and has expanded our synthetic capabilities. As a result many new preparative routes have been designed towards commercially relevant drug compounds achieving more efficient and reproducible manufacture. This review article aims to illustrate the holistic systems approach and diverse applications of flow chemistry to the preparation of pharmaceutically active molecules, demonstrating the value of this strategy towards every aspect ranging from synthesis, in-line analysis and purification to final formulation and tableting. Although this review will primarily concentrate on large scale continuous processing, additional selected syntheses using micro or meso-scaled flow reactors will be exemplified for key transformations and process control. It is hoped that the reader will gain an appreciation of the innovative technology and transformational nature that flow chemistry can leverage to an overall process.
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Affiliation(s)
- Marcus Baumann
- Department of Chemistry, Durham University, South Road, DH1 3LE Durham, United Kingdom
| | - Ian R Baxendale
- Department of Chemistry, Durham University, South Road, DH1 3LE Durham, United Kingdom
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35
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Gutmann B, Cantillo D, Kappe CO. Continuous-flow technology—a tool for the safe manufacturing of active pharmaceutical ingredients. Angew Chem Int Ed Engl 2015; 54:6688-728. [PMID: 25989203 DOI: 10.1002/anie.201409318] [Citation(s) in RCA: 870] [Impact Index Per Article: 96.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2014] [Indexed: 12/12/2022]
Abstract
In the past few years, continuous-flow reactors with channel dimensions in the micro- or millimeter region have found widespread application in organic synthesis. The characteristic properties of these reactors are their exceptionally fast heat and mass transfer. In microstructured devices of this type, virtually instantaneous mixing can be achieved for all but the fastest reactions. Similarly, the accumulation of heat, formation of hot spots, and dangers of thermal runaways can be prevented. As a result of the small reactor volumes, the overall safety of the process is significantly improved, even when harsh reaction conditions are used. Thus, microreactor technology offers a unique way to perform ultrafast, exothermic reactions, and allows the execution of reactions which proceed via highly unstable or even explosive intermediates. This Review discusses recent literature examples of continuous-flow organic synthesis where hazardous reactions or extreme process windows have been employed, with a focus on applications of relevance to the preparation of pharmaceuticals.
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Affiliation(s)
- Bernhard Gutmann
- Institute of Chemistry, University Graz, NAWI Graz, Heinrichstrasse 28, A-8010 Graz (Austria) http://www.maos.net
| | - David Cantillo
- Institute of Chemistry, University Graz, NAWI Graz, Heinrichstrasse 28, A-8010 Graz (Austria) http://www.maos.net
| | - C Oliver Kappe
- Institute of Chemistry, University Graz, NAWI Graz, Heinrichstrasse 28, A-8010 Graz (Austria) http://www.maos.net.
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36
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Gutmann B, Cantillo D, Kappe CO. Kontinuierliche Durchflussverfahren: ein Werkzeug für die sichere Synthese von pharmazeutischen Wirkstoffen. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201409318] [Citation(s) in RCA: 187] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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37
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Müller STR, Murat A, Maillos D, Lesimple P, Hellier P, Wirth T. Rapid Generation and Safe Use of Carbenes Enabled by a Novel Flow Protocol with In-line IR spectroscopy. Chemistry 2015; 21:7016-20. [DOI: 10.1002/chem.201500416] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2015] [Indexed: 11/06/2022]
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38
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Potter G, Budge SM, Speers RA. Beyond diazomethane: Alternative approaches to analyzing non‐esterified fatty acids. EUR J LIPID SCI TECH 2015. [DOI: 10.1002/ejlt.201400404] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Greg Potter
- Process Engineering and Applied ScienceDalhousie UniversityHalifaxCanada
| | - Suzanne M. Budge
- Process Engineering and Applied ScienceDalhousie UniversityHalifaxCanada
| | - R. Alex Speers
- The International Center for Brewing and DistillingSchool of Life SciencesHeriot‐Watt UniversityRiccartonEdinburghScotland
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39
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Müller STR, Wirth T. Diazo compounds in continuous-flow technology. CHEMSUSCHEM 2015; 8:245-250. [PMID: 25488620 DOI: 10.1002/cssc.201402874] [Citation(s) in RCA: 110] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Indexed: 06/04/2023]
Abstract
Diazo compounds are very versatile reagents in organic chemistry and meet the challenge of selective assembly of structurally complex molecules. Their leaving group is dinitrogen; therefore, they are very clean and atom-efficient reagents. However, diazo compounds are potentially explosive and extremely difficult to handle on an industrial scale. In this review, it is discussed how continuous flow technology can help to make these powerful reagents accessible on large scale. Microstructured devices can improve heat transfer greatly and help with the handling of dangerous reagents safely. The in situ formation and subsequent consumption of diazo compounds are discussed along with advances in handling diazomethane and ethyl diazoacetate. The potential large-scale applications of a given methodology is emphasized.
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Affiliation(s)
- Simon T R Müller
- School of Chemistry, Cardiff University, Park Place, Cardiff CF10 3AT (UK)
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40
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Deadman BJ, Collins SG, Maguire AR. Taming Hazardous Chemistry in Flow: The Continuous Processing of Diazo and Diazonium Compounds. Chemistry 2014; 21:2298-308. [DOI: 10.1002/chem.201404348] [Citation(s) in RCA: 150] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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41
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Tran DN, Battilocchio C, Lou SB, Hawkins JM, Ley SV. Flow chemistry as a discovery tool to access sp 2-sp 3 cross-coupling reactions via diazo compounds. Chem Sci 2014; 6:1120-1125. [PMID: 29560199 PMCID: PMC5811102 DOI: 10.1039/c4sc03072a] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Accepted: 11/07/2014] [Indexed: 11/21/2022] Open
Abstract
The room temperature sp2–sp3 cross-coupling of flow-generated diazo compounds with boronic acids is reported.
The work takes advantage of an important feature of flow chemistry, whereby the generation of a transient species (or reactive intermediate) can be followed by a transfer step into another chemical environment, before the intermediate is reacted with a coupling partner. This concept is successfully applied to achieve a room temperature sp2–sp3 cross coupling of boronic acids with diazo compounds, these latter species being generated from hydrazones under flow conditions using MnO2 as the oxidant.
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Affiliation(s)
- Duc N Tran
- Innovative Technology Centre , Department of Chemistry University of Cambridge , Lensfield Road , Cambridge , CB2 1EW , UK .
| | - Claudio Battilocchio
- Innovative Technology Centre , Department of Chemistry University of Cambridge , Lensfield Road , Cambridge , CB2 1EW , UK .
| | - Shing-Bong Lou
- Innovative Technology Centre , Department of Chemistry University of Cambridge , Lensfield Road , Cambridge , CB2 1EW , UK .
| | - Joel M Hawkins
- Pfizer Worldwide Research and Development , Eastern Point Road , Groton , CT 06340 , USA
| | - Steven V Ley
- Innovative Technology Centre , Department of Chemistry University of Cambridge , Lensfield Road , Cambridge , CB2 1EW , UK .
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42
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Zhang L. A non-diazo approach to α-oxo gold carbenes via gold-catalyzed alkyne oxidation. Acc Chem Res 2014; 47:877-88. [PMID: 24428596 PMCID: PMC3983127 DOI: 10.1021/ar400181x] [Citation(s) in RCA: 574] [Impact Index Per Article: 57.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Indexed: 12/24/2022]
Abstract
For the past dozen years, homogeneous gold catalysis has evolved from a little known topic in organic synthesis to a fully blown research field of significant importance to synthetic practitioners, due to its novel reactivities and reaction modes. Cationic gold(I) complexes are powerful soft Lewis acids that can activate alkynes and allenes toward efficient attack by nucleophiles, leading to the generation of alkenyl gold intermediates. Some of the most versatile aspects of gold catalysis involve the generation of gold carbene intermediates, which occurs through the approach of an electrophile to the distal end of the alkenyl gold moiety, and their diverse transformations thereafter. On the other hand, α-oxo metal carbene/carbenoids are highly versatile intermediates in organic synthesis and can undergo various synthetically challenging yet highly valuable transformations such as C-H insertion, ylide formation, and cyclopropanation reactions. Metal-catalyzed dediazotizations of diazo carbonyl compounds are the principle and most reliable strategy to access them. Unfortunately, the substrates contain a highly energetic diazo moiety and are potentially explosive. Moreover, chemists need to use energetic reagents to prepare them, putting further constrains on operational safety. In this Account, we show that the unique access to the gold carbene species in homogeneous gold catalysis offers an opportunity to generate α-oxo gold carbenes if both nucleophile and electrophile are oxygen. Hence, this approach would enable readily available and safer alkynes to replace hazardous α-diazo carbonyl compounds as precursors in the realm of gold carbene chemistry. For the past several years, we have demonstrated that alkynes can indeed effectively serve as precursors to versatile α-oxo gold carbenes. In our initial study, we showed that a tethered sulfoxide can be a suitable oxidant, which in some cases leads to the formation of α-oxo gold carbene intermediates. The intermolecular approach offers excellent synthetic flexibility because no tethering of the oxidant is required, and its reduced form is not tangled with the product. We were the first research group to develop this strategy, through the use of pyridine/quinolone N-oxides as the external oxidants. In this manner, we can effectively make a C-C triple bond a surrogate of an α-diazo carbonyl moiety in various gold catalyses. With terminal alkynes, we demonstrated that we can efficiently trap exclusively formed terminal carbene centers by internal nucleophiles en route to the formation of cyclic products, including strained oxetan-3-ones and azetidin-3-ones, and by external nucleophiles when a P,N-bidentate ligand is coordinated to gold. With internal alkynes, we generated synthetically useful regioselectivities in the generation of the α-oxo gold carbene moiety, which enables expedient formation of versatile enone products. Other research groups have also applied this strategy en route to versatile synthetic methods. The α-oxo gold carbenes appear to be more electrophilic than their Rh counterpart, which many chemists have focused on in a large array of excellent work on metal carbene chemistry. The ease of accessing the reactive gold carbenes opens up a vast area for developing new synthetic methods that would be distinctively different from the known Rh chemistry and promises to generate a new round of "gold rush".
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Affiliation(s)
- Liming Zhang
- Department of Chemistry and Biochemistry, University of California , Santa Barbara, California 93106, United States
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43
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Pinho VD, Gutmann B, Miranda LSM, de Souza ROMA, Kappe CO. Continuous flow synthesis of α-halo ketones: essential building blocks of antiretroviral agents. J Org Chem 2014; 79:1555-62. [PMID: 24471789 DOI: 10.1021/jo402849z] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The development of a continuous flow process for the multistep synthesis of α-halo ketones starting from N-protected amino acids is described. The obtained α-halo ketones are chiral building blocks for the synthesis of HIV protease inhibitors, such as atazanavir and darunavir. The synthesis starts with the formation of a mixed anhydride in a first tubular reactor. The anhydride is subsequently combined with anhydrous diazomethane in a tube-in-tube reactor. The tube-in-tube reactor consists of an inner tube, made from a gas-permeable, hydrophobic material, enclosed in a thick-walled, impermeable outer tube. Diazomethane is generated in the inner tube in an aqueous medium, and anhydrous diazomethane subsequently diffuses through the permeable membrane into the outer chamber. The α-diazo ketone is produced from the mixed anhydride and diazomethane in the outer chamber, and the resulting diazo ketone is finally converted to the halo ketone with anhydrous ethereal hydrogen halide. This method eliminates the need to store, transport, or handle diazomethane and produces α-halo ketone building blocks in a multistep system without racemization in excellent yields. A fully continuous process allowed the synthesis of 1.84 g of α-chloro ketone from the respective N-protected amino acid within ~4.5 h (87% yield).
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Affiliation(s)
- Vagner D Pinho
- Institute of Chemistry, University of Graz , Heinrichstrasse 28, A-8010 Graz, Austria
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44
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Mastronardi F, Gutmann B, Kappe CO. Continuous flow generation and reactions of anhydrous diazomethane using a Teflon AF-2400 tube-in-tube reactor. Org Lett 2013; 15:5590-3. [PMID: 24128181 DOI: 10.1021/ol4027914] [Citation(s) in RCA: 139] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
A continuous process for generation, separation, and reactions of anhydrous diazomethane in a tube-in-tube reactor was developed. The inner tube of the reactor is made of hydrophobic, gas-permeable Teflon AF-2400. The diazomethane is formed in the inner tube and then diffuses through the permeable membrane into the outer chamber and subsequently reacts in the solution carried within. This technique allows safe and scalable reactions with dry diazomethane to be performed on a laboratory scale.
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Affiliation(s)
- Federica Mastronardi
- Institute of Chemistry, University of Graz , Heinrichstrasse 28, A-8010 Graz, Austria
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45
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Damm M, Gutmann B, Kappe CO. Continuous-flow synthesis of adipic acid from cyclohexene using hydrogen peroxide in high-temperature explosive regimes. CHEMSUSCHEM 2013; 6:978-982. [PMID: 23592635 DOI: 10.1002/cssc.201300197] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Indexed: 06/02/2023]
Abstract
Safe only in a microreactor! The synthesis of adipic acid from cyclohexene by tungstic acid-catalyzed oxidation using hydrogen peroxide following the classical Noyori protocol can be accomplished in good yields with residence times as short as 20 min at 140 °C using a safe and scalable microreactor environment. Under these intensified conditions the use of a phase-transfer catalyst is not required.
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Affiliation(s)
- Markus Damm
- Christian Doppler Laboratory for Microwave Chemistry (CDLMC) and Institute of Chemistry, Karl-Franzens-University Graz, Heinrichstrasse 28, A-8010 Graz, Austria
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46
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Protasova LN, Bulut M, Ormerod D, Buekenhoudt A, Berton J, Stevens CV. Latest Highlights in Liquid-Phase Reactions for Organic Synthesis in Microreactors. Org Process Res Dev 2013. [DOI: 10.1021/op4000169] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- L. N. Protasova
- Department of Separation and
Conversion Technology, Flemish Institute for Technological Research (VITO), Boeretang 200, 2400 Mol, Belgium
| | | | | | | | - J. Berton
- Department of Sustainable Organic
Chemistry and Technology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Ghent,
Belgium
| | - C. V. Stevens
- Department of Sustainable Organic
Chemistry and Technology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Ghent,
Belgium
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