1
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Pasca F, Gelato Y, Andresini M, Romanazzi G, Degennaro L, Colella M, Luisi R. Synthesis of alcohols: streamlined C1 to C n hydroxyalkylation through photoredox catalysis. Chem Sci 2024; 15:11337-11346. [PMID: 39055000 PMCID: PMC11268494 DOI: 10.1039/d4sc02696a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2024] [Accepted: 06/05/2024] [Indexed: 07/27/2024] Open
Abstract
Naturally occurring and readily available α-hydroxy carboxylic acids (AHAs) are utilized as platforms for visible light-mediated oxidative CO2-extrusion furnishing α-hydroxy radicals proved to be versatile C1 to Cn hydroxyalkylating agents. The direct decarboxylative Giese reaction (DDGR) is operationally simple, not requiring activator or sacrificial oxidants, and enables the synthesis of a diverse range of hydroxylated products, introducing connectivity typically precluded from conventional polar domains. Notably, the methodology has been extended to widely used glycolic acid resulting in a highly efficient and unprecedented C1 hydroxyhomologation tactic. The use of flow technology further facilitates scalability and adds green credentials to this synthetic methodology.
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Affiliation(s)
- Francesco Pasca
- Department of Pharmacy-Drug Sciences, Flow Chemistry and Microreactor Technology FLAME-Lab University of Bari "A. Moro" Via E. Orabona 4 70125 Bari Italy
| | - Yuri Gelato
- Department of Pharmacy-Drug Sciences, Flow Chemistry and Microreactor Technology FLAME-Lab University of Bari "A. Moro" Via E. Orabona 4 70125 Bari Italy
| | - Michael Andresini
- Department of Pharmacy-Drug Sciences, Flow Chemistry and Microreactor Technology FLAME-Lab University of Bari "A. Moro" Via E. Orabona 4 70125 Bari Italy
| | | | - Leonardo Degennaro
- Department of Pharmacy-Drug Sciences, Flow Chemistry and Microreactor Technology FLAME-Lab University of Bari "A. Moro" Via E. Orabona 4 70125 Bari Italy
| | - Marco Colella
- Department of Pharmacy-Drug Sciences, Flow Chemistry and Microreactor Technology FLAME-Lab University of Bari "A. Moro" Via E. Orabona 4 70125 Bari Italy
| | - Renzo Luisi
- Department of Pharmacy-Drug Sciences, Flow Chemistry and Microreactor Technology FLAME-Lab University of Bari "A. Moro" Via E. Orabona 4 70125 Bari Italy
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2
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Phelps J, Kumar R, Robinson JD, Chu JCK, Flodén NJ, Beaton S, Gaunt MJ. Multicomponent Synthesis of α-Branched Amines via a Zinc-Mediated Carbonyl Alkylative Amination Reaction. J Am Chem Soc 2024; 146:9045-9062. [PMID: 38488310 PMCID: PMC10996026 DOI: 10.1021/jacs.3c14037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 02/09/2024] [Accepted: 02/20/2024] [Indexed: 03/21/2024]
Abstract
Methods for the synthesis of α-branched alkylamines are important due to their ubiquity in biologically active molecules. Despite the development of many methods for amine preparation, C(sp3)-rich nitrogen-containing compounds continue to pose challenges for synthesis. While carbonyl reductive amination (CRA) between ketones and alkylamines is the cornerstone method for α-branched alkylamine synthesis, it is sometimes limited by the sterically demanding condensation step between dialkyl ketones and amines and the more restricted availability of ketones compared to aldehydes. We recently reported a "higher-order" variant of this transformation, carbonyl alkylative amination (CAA), which utilized a halogen atom transfer (XAT)-mediated radical mechanism, enabling the streamlined synthesis of complex α-branched alkylamines. Despite the efficacy of this visible-light-driven approach, it displayed scalability issues, and competitive reductive amination was a problem for certain substrate classes, limiting applicability. Here, we report a change in the reaction regime that expands the CAA platform through the realization of an extremely broad zinc-mediated CAA reaction. This new strategy enabled elimination of competitive CRA, simplified purification, and improved reaction scope. Furthermore, this new reaction harnessed carboxylic acid derivatives as alkyl donors and facilitated the synthesis of α-trialkyl tertiary amines, which cannot be accessed via CRA. This Zn-mediated CAA reaction can be carried out at a variety of scales, from a 10 μmol setup in microtiter plates enabling high-throughput experimentation, to the gram-scale synthesis of medicinally-relevant compounds. We believe that this transformation enables robust, efficient, and economical access to α-branched alkylamines and provides a viable alternative to the current benchmark methods.
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Affiliation(s)
| | | | | | | | - Nils J. Flodén
- Yusuf Hamied Department of
Chemistry, University of Cambridge, Cambridge CB2 1EW, United Kingdom
| | - Sarah Beaton
- Yusuf Hamied Department of
Chemistry, University of Cambridge, Cambridge CB2 1EW, United Kingdom
| | - Matthew J. Gaunt
- Yusuf Hamied Department of
Chemistry, University of Cambridge, Cambridge CB2 1EW, United Kingdom
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3
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Cao Q, Tibbetts JD, Wrigley GL, Smalley AP, Cresswell AJ. Modular, automated synthesis of spirocyclic tetrahydronaphthyridines from primary alkylamines. Commun Chem 2023; 6:215. [PMID: 37794068 PMCID: PMC10550966 DOI: 10.1038/s42004-023-01012-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Accepted: 09/22/2023] [Indexed: 10/06/2023] Open
Abstract
Spirocyclic tetrahydronaphthyridines (THNs) are valuable scaffolds for drug discovery campaigns, but access to this 3D chemical space is hampered by a lack of modular and scalable synthetic methods. We hereby report an automated, continuous flow synthesis of α-alkylated and spirocyclic 1,2,3,4-tetrahydro-1,8-naphthyridines ("1,8-THNs"), in addition to their regioisomeric 1,6-THN analogues, from abundant primary amine feedstocks. An annulative disconnection approach based on photoredox-catalysed hydroaminoalkylation (HAA) of halogenated vinylpyridines is sequenced in combination with intramolecular SNAr N-arylation. To access the remaining 1,7- and 1,5-THN isomers, a photoredox-catalysed HAA step is telescoped with a palladium-catalysed C-N bond formation. Altogether, this provides a highly modular access to four isomeric THN cores from a common set of unprotected primary amine starting materials, using the same bond disconnections. The simplifying power of the methodology is illustrated by a concise synthesis of the spirocyclic THN core of Pfizer's MC4R antagonist PF-07258669.
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Affiliation(s)
- Qiao Cao
- Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK
| | - Joshua D Tibbetts
- Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK
| | - Gail L Wrigley
- Medicinal Chemistry, Oncology R&D, AstraZeneca, Cambridge, CB4 0WG, UK
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4
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Pagire S, Shu C, Reich D, Noble A, Aggarwal VK. Convergent Deboronative and Decarboxylative Phosphonylation Enabled by the Phosphite Radical Trap "BecaP". J Am Chem Soc 2023; 145:18649-18657. [PMID: 37552886 PMCID: PMC10450818 DOI: 10.1021/jacs.3c06524] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Indexed: 08/10/2023]
Abstract
Carbon-phosphorus bond formation is significant in synthetic chemistry because phosphorus-containing compounds offer numerous indispensable biochemical roles. While there is a plethora of methods to access organophosphorus compounds, phosphonylations of readily accessible alkyl radicals to form aliphatic phosphonates are rare and not commonly used in synthesis. Herein, we introduce a novel phosphorus radical trap "BecaP" that enables facile and efficient phosphonylation of alkyl radicals under visible light photocatalytic conditions. Importantly, the ambiphilic nature of BecaP allows redox neutral reactions with both nucleophilic (activated by single-electron oxidation) and electrophilic (activated by single-electron reduction) alkyl radical precursors. Thus, a broad scope of feedstock alkyl potassium trifluoroborate salts and redox active carboxylate esters could be employed, with each class of substrate proceeding through a distinct mechanistic pathway. The mild conditions are applicable to the late-stage installation of phosphonate motifs into medicinal agents and natural products, which is showcased by the straightforward conversion of baclofen (muscle relaxant) to phaclofen (GABAB antagonist).
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Affiliation(s)
- Santosh
K. Pagire
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, U.K.
| | - Chao Shu
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, U.K.
- National
Key Laboratory of Green Pesticide, College of Chemistry, Central China Normal University (CCNU), 152 Luoyu Road, Wuhan, Hubei 430079, China
| | - Dominik Reich
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, U.K.
| | - Adam Noble
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, U.K.
| | - Varinder K. Aggarwal
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, U.K.
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5
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Meger FS, Murphy JA. Recent Advances in C-H Functionalisation through Indirect Hydrogen Atom Transfer. Molecules 2023; 28:6127. [PMID: 37630379 PMCID: PMC10459052 DOI: 10.3390/molecules28166127] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2023] [Revised: 08/09/2023] [Accepted: 08/15/2023] [Indexed: 08/27/2023] Open
Abstract
The functionalisation of C-H bonds has been an enormous achievement in synthetic methodology, enabling new retrosynthetic disconnections and affording simple synthetic equivalents for synthons. Hydrogen atom transfer (HAT) is a key method for forming alkyl radicals from C-H substrates. Classic reactions, including the Barton nitrite ester reaction and Hofmann-Löffler-Freytag reaction, among others, provided early examples of HAT. However, recent developments in photoredox catalysis and electrochemistry have made HAT a powerful synthetic tool capable of introducing a wide range of functional groups into C-H bonds. Moreover, greater mechanistic insights into HAT have stimulated the development of increasingly site-selective protocols. Site-selectivity can be achieved through the tuning of electron density at certain C-H bonds using additives, a judicious choice of HAT reagent, and a solvent system. Herein, we describe the latest methods for functionalizing C-H/Si-H/Ge-H bonds using indirect HAT between 2018-2023, as well as a critical discussion of new HAT reagents, mechanistic aspects, substrate scopes, and background contexts of the protocols.
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Affiliation(s)
- Filip S. Meger
- Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology, 16 Avinguda dels Països Catalans, 43007 Tarragona, Catalonia, Spain
| | - John A. Murphy
- Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow G1 1XL, UK
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6
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Sneha M, Thornton GL, Lewis-Borrell L, Ryder ASH, Espley SG, Clark IP, Cresswell AJ, Grayson MN, Orr-Ewing AJ. Photoredox-HAT Catalysis for Primary Amine α-C-H Alkylation: Mechanistic Insight with Transient Absorption Spectroscopy. ACS Catal 2023; 13:8004-8013. [PMID: 37342833 PMCID: PMC10278065 DOI: 10.1021/acscatal.3c01474] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 05/17/2023] [Indexed: 06/23/2023]
Abstract
The synergistic use of (organo)photoredox catalysts with hydrogen-atom transfer (HAT) cocatalysts has emerged as a powerful strategy for innate C(sp3)-H bond functionalization, particularly for C-H bonds α- to nitrogen. Azide ion (N3-) was recently identified as an effective HAT catalyst for the challenging α-C-H alkylation of unprotected, primary alkylamines, in combination with dicyanoarene photocatalysts such as 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN). Here, time-resolved transient absorption spectroscopy over sub-picosecond to microsecond timescales provides kinetic and mechanistic details of the photoredox catalytic cycle in acetonitrile solution. Direct observation of the electron transfer from N3- to photoexcited 4CzIPN reveals the participation of the S1 excited electronic state of the organic photocatalyst as an electron acceptor, but the N3• radical product of this reaction is not observed. Instead, both time-resolved infrared and UV-visible spectroscopic measurements implicate rapid association of N3• with N3- (a favorable process in acetonitrile) to form the N6•- radical anion. Electronic structure calculations indicate that N3• is the active participant in the HAT reaction, suggesting a role for N6•- as a reservoir that regulates the concentration of N3•.
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Affiliation(s)
- Mahima Sneha
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, U.K.
- Department
of Chemistry, Dartmouth College, Hanover, New Hampshire 03755, United States
| | - Georgia L. Thornton
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, U.K.
| | - Luke Lewis-Borrell
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, U.K.
| | - Alison S. H. Ryder
- Centre
for Sustainable Chemical Technologies, University
of Bath, 1 South, Claverton Down, Bath BA2 7AY, U.K.
| | - Samuel G. Espley
- Department
of Chemistry, University of Bath, 1 South, Claverton Down, Bath BA2 7AY, U.K.
| | - Ian P. Clark
- Central
Laser Facility, Research Complex at Harwell, Science and Technology
Facilities Council, Rutherford Appleton
Laboratory, Harwell Oxford, Didcot OX11 0QX, U.K.
| | - Alexander J. Cresswell
- Department
of Chemistry, University of Bath, 1 South, Claverton Down, Bath BA2 7AY, U.K.
| | - Matthew N. Grayson
- Department
of Chemistry, University of Bath, 1 South, Claverton Down, Bath BA2 7AY, U.K.
| | - Andrew J. Orr-Ewing
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, U.K.
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7
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Sakai K, Oisaki K, Kanai M. A Germanium Catalyst Accelerates the Photoredox α-C(sp 3)-H Alkylation of Primary Amines. Org Lett 2022; 24:3325-3330. [PMID: 35486160 DOI: 10.1021/acs.orglett.2c00871] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Site-selective C(sp3)-H functionalizations using photoredox catalysis (PC) and hydrogen atom transfer (HAT) catalysis have received increasing attention. Here, we report a Ph2GeCl2 cocatalyst that greatly improves the yield of α-C(sp3)-H alkylation of primary amines catalyzed by a PC-HAT hybrid system. The α-position of the amino group selectively reacted even when weaker C-H bonds existed in the substrates. This finding may help the design of a novel site-selective hybrid catalysis.
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Affiliation(s)
- Kentaro Sakai
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
| | - Kounosuke Oisaki
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
| | - Motomu Kanai
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
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8
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Shee M, Singh NDP. Chemical versatility of azide radical: journey from a transient species to synthetic accessibility in organic transformations. Chem Soc Rev 2022; 51:2255-2312. [PMID: 35229836 DOI: 10.1039/d1cs00494h] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The generation of azide radical (N3˙) occurs from its precursors primarily via a single electron transfer (SET) process or homolytic cleavage by chemical methods or advanced photoredox/electrochemical methods. This in situ generated transient open-shell species has unique characteristic features that set its reactivity. In the past, the azide radical was widely used for various studies in radiation chemistry as a 1e- oxidant of biologically important molecules, but now it is being exploited for synthetic applications based on its addition and intermolecular hydrogen atom transfer (HAT) abilities. Due to the significant role of nitrogen-containing molecules in synthesis, drug discovery, biological, and material sciences, the direct addition onto unsaturated bonds for the simultaneous construction of C-N bond with other (C-X) bonds are indeed worth highlighting. Moreover, the ability to generate O- or C-centered radicals by N3˙ via electron transfer (ET) and intermolecular HAT processes is also well documented. The purpose of controlling the reactivity of this short-lived intermediate in organic transformations drives us to survey: (i) the history of azide radical and its structural properties (thermodynamic, spectroscopic, etc.), (ii) chemical reactivities and kinetics, (iii) methods to produce N3˙ from various precursors, (iv) several significant azide radical-mediated transformations in the field of functionalization with unsaturated bonds, C-H functionalization via HAT, tandem, and multicomponent reaction with a critical analysis of underlying mechanistic approaches and outcomes, (v) concept of taming the reactivity of azide radicals for potential opportunities, in this review.
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Affiliation(s)
- Maniklal Shee
- Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal, 721302, India.
| | - N D Pradeep Singh
- Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal, 721302, India.
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9
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Kinsella AG, Tibbetts JD, Stead D, Cresswell AJ. N-tosylhydrazones as acceptors for nucleophilic alkyl radicals in photoredox catalysis: A short case study on possible side reactions. SYNTHETIC COMMUN 2022. [DOI: 10.1080/00397911.2022.2028844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
| | | | - Darren Stead
- AstraZeneca, Oncology R&D, Research & Early Development, Cambridge, UK
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10
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Gentleman AS, Lawson T, Ellis MG, Davis M, Turner-Dore J, Ryder ASH, Frosz MH, Ciaccia M, Reisner E, Cresswell AJ, Euser TG. Stern–Volmer analysis of photocatalyst fluorescence quenching within hollow-core photonic crystal fibre microreactors. Chem Commun (Camb) 2022; 58:10548-10551. [DOI: 10.1039/d2cc03996f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Optofluidic microreactors enable Stern–Volmer analysis on nanolitre-scale photocatalyst–quencher mixtures. The method is used to measure bimolecular quenching coefficients for a photoredox-catalysed α-C–H alkylation reaction of primary alkylamines.
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Affiliation(s)
- Alexander S. Gentleman
- Nanophotonics Centre, The Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge, CB3 0HE, UK
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Takashi Lawson
- Nanophotonics Centre, The Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge, CB3 0HE, UK
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Matthew G. Ellis
- Nanophotonics Centre, The Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge, CB3 0HE, UK
| | - Molly Davis
- Nanophotonics Centre, The Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge, CB3 0HE, UK
| | - Jacob Turner-Dore
- Department of Chemistry, University of Bath, 1 South, Claverton Down, Bath, BA2 7AY, UK
| | - Alison S. H. Ryder
- Department of Chemistry, University of Bath, 1 South, Claverton Down, Bath, BA2 7AY, UK
| | - Michael H. Frosz
- Max Planck Institute for the Science of Light, Staudtstr. 2, 91058, Erlangen, Germany
| | - Maria Ciaccia
- Syngenta, Jealott's Hill Research Centre, Bracknell, Berkshire, RG52 6EY, UK
| | - Erwin Reisner
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | | | - Tijmen G. Euser
- Nanophotonics Centre, The Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge, CB3 0HE, UK
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11
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Helesbeux JJ, Carro L, McCarthy FO, Moreira VM, Giuntini F, O’Boyle N, Matthews SE, Bayraktar G, Bertrand S, Rochais C, Marchand P. 29th Annual GP2A Medicinal Chemistry Conference. Pharmaceuticals (Basel) 2021; 14:ph14121278. [PMID: 34959677 PMCID: PMC8708472 DOI: 10.3390/ph14121278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 11/18/2021] [Indexed: 11/16/2022] Open
Abstract
The 29th Annual GP2A (Group for the Promotion of Pharmaceutical chemistry in Academia) Conference was a virtual event this year due to the COVID-19 pandemic and spanned three days from Wednesday 25 to Friday 27 August 2021. The meeting brought together an international delegation of researchers with interests in medicinal chemistry and interfacing disciplines. Abstracts of keynote lectures given by the 10 invited speakers, along with those of the 8 young researcher talks and the 50 flash presentation posters, are included in this report. Like previous editions, the conference was a real success, with high-level scientific discussions on cutting-edge advances in the fields of pharmaceutical chemistry.
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Affiliation(s)
| | - Laura Carro
- School of Pharmacy, University College London, London WC1N 1AX, UK;
| | - Florence O. McCarthy
- School of Chemistry, Analytical and Biological Chemistry Research Facility, University College Cork, College Road, T12 K8AF Cork, Ireland;
| | - Vânia M. Moreira
- Laboratory of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Coimbra, Pólo das Ciências da Saúde, Azinhaga de Santa Comba, 3000-548 Coimbra, Portugal;
- Center for Neuroscience and Cell Biology, Faculty of Medicine, University of Coimbra, Rua Larga, 3004-504 Coimbra, Portugal
| | - Francesca Giuntini
- School of Pharmacy and Biomolecular Sciences, Byrom Street Campus, Liverpool John Moores University, Liverpool L3 3AF, UK;
| | - Niamh O’Boyle
- School of Pharmacy and Pharmaceutical Sciences, Panoz Institute, Trinity College Dublin, D02 R590 Dublin, Ireland;
| | - Susan E. Matthews
- School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK;
| | - Gülşah Bayraktar
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Ege University, Izmir 35100, Turkey;
| | - Samuel Bertrand
- Institut des Substances et Organismes de la Mer, ISOmer, Nantes Université, UR 2160, F-44000 Nantes, France;
| | - Christophe Rochais
- UNICAEN, CERMN (Centre d’Etudes et de Recherche sur le Médicament de Normandie), Normandie Univ., F-14032 Caen, France;
| | - Pascal Marchand
- Cibles et Médicaments des Infections et du Cancer, IICiMed, Nantes Université, UR 1155, F-44000 Nantes, France
- Correspondence: ; Tel.: +33-253-009-155
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12
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Askey H, Grayson JD, Tibbetts JD, Turner-Dore JC, Holmes JM, Kociok-Kohn G, Wrigley GL, Cresswell AJ. Photocatalytic Hydroaminoalkylation of Styrenes with Unprotected Primary Alkylamines. J Am Chem Soc 2021; 143:15936-15945. [PMID: 34543004 PMCID: PMC8499025 DOI: 10.1021/jacs.1c07401] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Indexed: 12/27/2022]
Abstract
Catalytic, intermolecular hydroaminoalkylation (HAA) of styrenes provides a powerful disconnection for pharmacologically relevant γ-arylamines, but current methods cannot utilize unprotected primary alkylamines as feedstocks. Metal-catalyzed HAA protocols are also highly sensitive to α-substitution on the amine partner, and no catalytic solutions exist for α-tertiary γ-arylamine synthesis via this approach. We report a solution to these problems using organophotoredox catalysis, enabling a direct, modular, and sustainable preparation of α-(di)substituted γ-arylamines, including challenging electron-neutral and moderately electron-rich aryl groups. A broad range of functionalities are tolerated, and the reactions can be run on multigram scale in continuous flow. The method is applied to a concise, protecting-group-free synthesis of the blockbuster drug Fingolimod, as well as a phosphonate mimic of its in vivo active form (by iterative α-C-H functionalization of ethanolamine). The reaction can also be sequenced with an intramolecular N-arylation to provide a general and modular access to valuable (spirocyclic) 1,2,3,4-tetrahydroquinolines and 1,2,3,4-tetrahydronaphthyridines. Mechanistic and kinetic studies support an irreversible hydrogen atom transfer activation of the alkylamine by the azidyl radical and some contribution from a radical chain. The reaction is photon-limited and exhibits a zero-order dependence on amine, azide, and photocatalyst, with a first-order dependence on styrene.
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Affiliation(s)
- Hannah
E. Askey
- Department
of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, U.K.
| | - James D. Grayson
- Department
of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, U.K.
| | - Joshua D. Tibbetts
- Department
of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, U.K.
| | | | - Jake M. Holmes
- Department
of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, U.K.
| | - Gabriele Kociok-Kohn
- Materials
and Chemical Characterisation Facility (MC), University of Bath, Claverton Down, Bath BA2 7AY, U.K.
| | - Gail L. Wrigley
- Oncology
R&D, Research & Early Development, AstraZeneca, Darwin Building, 310, Cambridge Science Park, Milton Road, Cambridge CB4 0WG, U.K.
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