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Ruyet L, Roblick C, Häfliger J, Wang ZX, Stoffels TJ, Daniliuc CG, Gilmour R. Catalytic Ring Expanding Difluorination: An Enantioselective Platform to Access β,β-Difluorinated Carbocycles. Angew Chem Int Ed Engl 2024; 63:e202403957. [PMID: 38482736 DOI: 10.1002/anie.202403957] [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: 02/26/2024] [Indexed: 04/11/2024]
Abstract
Cyclic β,β-difluoro-carbonyl compounds have a venerable history as drug discovery leads, but limitations in the synthesis arsenal continue to impede chemical space exploration. This challenge is particularly acute in the arena of fluorinated medium rings where installing the difluoromethylene unit subtly alters the ring conformation by expanding the internal angle (∠C-CF2-C>∠C-CH2-C): this provides a handle to modulate physicochemistry (e.g. pKa). To reconcile this disparity, a highly modular ring expansion has been devised that leverages simple α,β-unsaturated esters and amides, and processes them to one-carbon homologated rings with concomitant geminal difluorination (6 to 10 membered rings, up to 95 % yield). This process is a rare example of the formal difluorination of an internal alkene and is enabled by sequential I(III)-enabled O-activation. Validation of enantioselective catalysis in the generation of unprecedented medium ring scaffolds is reported (up to 93 : 7 e.r.) together with X-ray structural analyses and product derivatization.
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Affiliation(s)
- Louise Ruyet
- University of Münster, Institute for Organic Chemistry, Corrensstraße 36, 48149, Münster, Germany
| | - Christoph Roblick
- University of Münster, Institute for Organic Chemistry, Corrensstraße 36, 48149, Münster, Germany
| | - Joel Häfliger
- University of Münster, Institute for Organic Chemistry, Corrensstraße 36, 48149, Münster, Germany
| | - Zi-Xuan Wang
- University of Münster, Institute for Organic Chemistry, Corrensstraße 36, 48149, Münster, Germany
| | - Tobias Jürgen Stoffels
- University of Münster, Institute for Organic Chemistry, Corrensstraße 36, 48149, Münster, Germany
| | - Constantin G Daniliuc
- University of Münster, Institute for Organic Chemistry, Corrensstraße 36, 48149, Münster, Germany
| | - Ryan Gilmour
- University of Münster, Institute for Organic Chemistry, Corrensstraße 36, 48149, Münster, Germany
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2
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Longuet M, Vitse K, Martin-Mingot A, Michelet B, Guégan F, Thibaudeau S. Determination of the Hammett Acidity of HF/Base Reagents. J Am Chem Soc 2024; 146:12167-12173. [PMID: 38626381 DOI: 10.1021/jacs.4c02344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/18/2024]
Abstract
Harnessing the acidity of HF/base reagents is of paramount importance to improve the efficiency and selectivity of fluorination reactions. Yet, no general method has been reported to evaluate their acidic properties, and experimental designs are still relying on a trial-and-error approach. We report a new method based on 19F NMR spectroscopy which allows highly sensitive measures and short-time analyses. Advantageously, the basic properties of the indicators can be determined upstream by DFT calculations, affording a simple yet robust semiempirical approach. In particular, the indicators used in this study were rationally designed to fit on the conceptually appealing and commonly used Hammett scale. This method has been applied to commercially available and recently developed HF/base reagents.
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Affiliation(s)
- Mélissa Longuet
- UMR-CNRS 7285, IC2MP, Université de Poitiers, 4 rue Michel Brunet, TSA 51106, Poitiers Cedex 9 86073, France
| | - Kassandra Vitse
- UMR-CNRS 7285, IC2MP, Université de Poitiers, 4 rue Michel Brunet, TSA 51106, Poitiers Cedex 9 86073, France
| | - Agnès Martin-Mingot
- UMR-CNRS 7285, IC2MP, Université de Poitiers, 4 rue Michel Brunet, TSA 51106, Poitiers Cedex 9 86073, France
| | - Bastien Michelet
- UMR-CNRS 7285, IC2MP, Université de Poitiers, 4 rue Michel Brunet, TSA 51106, Poitiers Cedex 9 86073, France
| | - Frédéric Guégan
- UMR-CNRS 7285, IC2MP, Université de Poitiers, 4 rue Michel Brunet, TSA 51106, Poitiers Cedex 9 86073, France
| | - Sébastien Thibaudeau
- UMR-CNRS 7285, IC2MP, Université de Poitiers, 4 rue Michel Brunet, TSA 51106, Poitiers Cedex 9 86073, France
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3
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Wang ZX, Livingstone K, Hümpel C, Daniliuc CG, Mück-Lichtenfeld C, Gilmour R. Regioselective, catalytic 1,1-difluorination of enynes. Nat Chem 2023; 15:1515-1522. [PMID: 37845310 PMCID: PMC10624631 DOI: 10.1038/s41557-023-01344-5] [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: 02/22/2023] [Accepted: 09/12/2023] [Indexed: 10/18/2023]
Abstract
Fluorinated small molecules are prevalent across the functional small-molecule spectrum, but the scarcity of naturally occurring sources creates an opportunity for creative endeavour in developing routes to access these important materials. Iodine(I)/iodine(III) catalysis has proven to be particularly well-suited to this task, enabling abundant alkene substrates to be readily intercepted by in situ-generated λ3-iodanes and processed to high-value (di)fluorinated products. These organocatalysis paradigms often emulate metal-based processes by engaging the π bond and, in the case of styrenes, facilitating fluorinative phenonium-ion rearrangements to generate difluoromethylene units. Here we demonstrate that enynes are competent proxies for styrenes, thereby mitigating the recurrent need for aryl substituents, and enabling highly versatile homopropargylic difluorides to be generated in an operationally simple manner. The scope of the method is disclosed, together with application in target synthesis (>30 examples, up to >90% yield).
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Affiliation(s)
- Zi-Xuan Wang
- Institute for Organic Chemistry, Westfälische Wilhelms-Universität (WWU) Münster, Münster, Germany
| | - Keith Livingstone
- Institute for Organic Chemistry, Westfälische Wilhelms-Universität (WWU) Münster, Münster, Germany
| | - Carla Hümpel
- Institute for Organic Chemistry, Westfälische Wilhelms-Universität (WWU) Münster, Münster, Germany
| | - Constantin G Daniliuc
- Institute for Organic Chemistry, Westfälische Wilhelms-Universität (WWU) Münster, Münster, Germany
| | | | - Ryan Gilmour
- Institute for Organic Chemistry, Westfälische Wilhelms-Universität (WWU) Münster, Münster, Germany.
- Cells in Motion (CiM) Interfaculty Center, Westfälische Wilhelms-Universität (WWU) Münster, Münster, Germany.
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4
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Hoogesteger RH, Murdoch N, Cordes DB, Johnston CP. Cobalt-Catalyzed Wagner-Meerwein Rearrangements with Concomitant Nucleophilic Hydrofluorination. Angew Chem Int Ed Engl 2023; 62:e202308048. [PMID: 37409777 DOI: 10.1002/anie.202308048] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Revised: 07/04/2023] [Accepted: 07/05/2023] [Indexed: 07/07/2023]
Abstract
We report a cobalt-catalyzed Wagner-Meerwein rearrangement of gem-disubstituted allylarenes that generates fluoroalkane products with isolated yields up to 84 %. Modification of the counteranion of the N-fluoropyridinium oxidant suggests the substrates undergo nucleophilic fluorination during the reaction. Subjecting the substrates to other known metal-mediated hydrofluorination procedures did not lead to observable 1,2-aryl migration. Thus, indicating the unique ability of these cobalt-catalyzed conditions to generate a sufficiently reactive electrophilic intermediate capable of promoting this Wagner-Meerwein rearrangement.
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Affiliation(s)
- Reece H Hoogesteger
- EaStCHEM, School of Chemistry, University of St Andrews, St Andrews, Fife, KY16 9ST, UK
| | - Nicola Murdoch
- EaStCHEM, School of Chemistry, University of St Andrews, St Andrews, Fife, KY16 9ST, UK
| | - David B Cordes
- EaStCHEM, School of Chemistry, University of St Andrews, St Andrews, Fife, KY16 9ST, UK
| | - Craig P Johnston
- EaStCHEM, School of Chemistry, University of St Andrews, St Andrews, Fife, KY16 9ST, UK
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Yang S, Wu JY, Lin S, Pu M, Huang ZS, Wang H, Li Q. Divergent Fluorinations of Vinylcyclopropanes: Ring-Opening 1,5-Hydrofluorination and Ring-Retaining 1,2-Difluorination. Chem Asian J 2023; 18:e202300476. [PMID: 37366264 DOI: 10.1002/asia.202300476] [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: 05/29/2023] [Revised: 06/26/2023] [Accepted: 06/27/2023] [Indexed: 06/28/2023]
Abstract
Organofluorine compounds have been widely used in pharmaceutical, agrochemical, and material sciences. Reported herein are divergent fluorination reactions of vinylcyclopropanes with different electrophiles, which allow the facile synthesis of homoallylic monofluorides and vicinal-difluorides through ring-opening 1,5-hydrofluorination and ring-retaining 1,2-difluorination, respectively. Both protocols feature mild conditions, simple operations, good functional group tolerance, and generally good yields. The practicality of these reactions is demonstrated by their scalability, as well as the successful conversion of the formed homoallylic monofluorides into other complex fluorinated molecules.
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Affiliation(s)
- Shuang Yang
- Guangdong Provincial Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, P. R. China
| | - Jun-Yunzi Wu
- Guangdong Provincial Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, P. R. China
| | - Shuang Lin
- Guangdong Provincial Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, P. R. China
| | - Meicen Pu
- Department of Endocrinology and Metabolism, Nanfang Hospital of Southern Medical University, Guangzhou, 510515, P. R. China
| | - Zhi-Shu Huang
- Guangdong Provincial Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, P. R. China
| | - Honggen Wang
- Guangdong Provincial Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, P. R. China
| | - Qingjiang Li
- Guangdong Provincial Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, P. R. China
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Häfliger J, Ruyet L, Stübke N, Daniliuc CG, Gilmour R. Integrating I(I)/I(III) catalysis in reaction cascade design enables the synthesis of gem-difluorinated tetralins from cyclobutanols. Nat Commun 2023; 14:3207. [PMID: 37268631 DOI: 10.1038/s41467-023-38957-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Accepted: 05/16/2023] [Indexed: 06/04/2023] Open
Abstract
Partially saturated, fluorine-containing rings are ubiquitous across the drug discovery spectrum. This capitalises upon the biological significance of the native structure and the physicochemical advantages conferred by fluorination. Motivated by the significance of aryl tetralins in bioactive small molecules, a reaction cascade has been validated to generate novel gem-difluorinated isosteres from 1,3-diaryl cyclobutanols in a single operation. Under the Brønsted acidity of the catalysis conditions, an acid-catalysed unmasking/fluorination sequence generates a homoallylic fluoride in situ. This species serves as the substrate for an I(I)/I(III) cycle and is processed, via a phenonium ion rearrangement, to an (isolable) 1,3,3-trifluoride. A final C(sp3)-F bond activation event, enabled by HFIP, forges the difluorinated tetralin scaffold. The cascade is highly modular, enabling the intermediates to be intercepted: this provides an expansive platform for the generation of structural diversity.
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Affiliation(s)
- Joel Häfliger
- Institute for Organic Chemistry, Westfälische Wilhelms-Universität (WWU) Münster, Corrensstraße 36, 48149, Münster, Germany
| | - Louise Ruyet
- Institute for Organic Chemistry, Westfälische Wilhelms-Universität (WWU) Münster, Corrensstraße 36, 48149, Münster, Germany
| | - Nico Stübke
- Institute for Organic Chemistry, Westfälische Wilhelms-Universität (WWU) Münster, Corrensstraße 36, 48149, Münster, Germany
| | - Constantin G Daniliuc
- Institute for Organic Chemistry, Westfälische Wilhelms-Universität (WWU) Münster, Corrensstraße 36, 48149, Münster, Germany
| | - Ryan Gilmour
- Institute for Organic Chemistry, Westfälische Wilhelms-Universität (WWU) Münster, Corrensstraße 36, 48149, Münster, Germany.
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7
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Yu YJ, Schäfer M, Daniliuc CG, Gilmour R. Catalytic, Regioselective 1,4-Fluorodifunctionalization of Dienes. Angew Chem Int Ed Engl 2023; 62:e202214906. [PMID: 36345795 PMCID: PMC10107283 DOI: 10.1002/anie.202214906] [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: 10/10/2022] [Indexed: 11/09/2022]
Abstract
A catalysis-based regioselective 1,4-fluorofunctionalization of trifluoromethyl substituted 1,3-dienes has been developed to access compact, highly functionalized products. The process allows E,Z-mixed dienes to be processed to a single E-alkene isomer, and leverages an inexpensive and operationally convenient I(I)/I(III) catalysis platform. The first example of catalytic 1,4-difluorination is disclosed and subsequently evolved to enable 1,4-hetero-difunctionalization, which allows δ-fluoro-alcohol and amine derivatives to be forged in a single operation. The protocol is compatible with a variety of nucleophiles including fluoride, nitriles, carboxylic acids, alcohols and even water thereby allowing highly functionalized products, with a stereocenter bearing both C(sp3 )-F and C(sp3 )-CF3 groups, to be generated rapidly. Scalability (up to 3 mmol), and facile post-reaction modifications are demonstrated to underscore the utility of the method in expanding organofluorine chemical space.
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Affiliation(s)
- You-Jie Yu
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraße 36, 48149, Münster, Germany
| | - Michael Schäfer
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraße 36, 48149, Münster, Germany
| | - Constantin G Daniliuc
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraße 36, 48149, Münster, Germany
| | - Ryan Gilmour
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraße 36, 48149, Münster, Germany
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8
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Livingstone K, Siebold K, Meyer S, Martín-Heras V, Daniliuc CG, Gilmour R. Skeletal Ring Contractions via I(I)/I(III) Catalysis: Stereoselective Synthesis of cis-α,α-Difluorocyclopropanes. ACS Catal 2022; 12:14507-14516. [PMID: 36504915 PMCID: PMC9724094 DOI: 10.1021/acscatal.2c04511] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 10/17/2022] [Indexed: 11/12/2022]
Abstract
The clinical success of α,α-difluorocyclopropanes, combined with limitations in the existing synthesis portfolio, inspired the development of an operationally simple, organocatalysis-based strategy to access cis-configured derivatives with high levels of stereoselectivity (up to >20:1 cis:trans). Leveraging an I(I)/I(III)-catalysis platform in the presence of an inexpensive HF source, it has been possible to exploit disubstituted bicyclobutanes (BCBs) as masked cyclobutene equivalents for this purpose. In situ generation of this strained alkene, enabled by Brønsted acid activation, facilitates an unprecedented 4 → 3 fluorinative ring contraction, to furnish cis-α,α-difluorinated cyclopropanes in a highly stereoselective manner (up to 88% yield). Mechanistic studies are disclosed together with conformational analysis (X-ray crystallography and NMR) to validate cis-α,α-difluorocyclopropanes as isosteres of the 1,4-dicarbonyl moiety. Given the importance of this unit in biology and the foundational no → π* interactions that manifest themselves in this conformation (e.g., collagen), it is envisaged that the title motif will find application in focused molecular design.
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