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Xu J. Syntheses of 1,2‐Oxaphospholane 2‐Oxides and 1,2‐Oxaphosphole 2‐Oxides. ChemistrySelect 2023. [DOI: 10.1002/slct.202300217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/29/2023]
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2
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Exploiting photoredox catalysis for carbohydrate modification through C–H and C–C bond activation. Nat Rev Chem 2022; 6:782-805. [PMID: 37118094 DOI: 10.1038/s41570-022-00422-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/12/2022] [Indexed: 11/09/2022]
Abstract
Photoredox catalysis has recently emerged as a powerful synthetic platform for accessing complex chemical structures through non-traditional bond disconnection strategies that proceed through free-radical intermediates. Such synthetic strategies have been used for a range of organic transformations; however, in carbohydrate chemistry they have primarily been applied to the generation of oxocarbenium ion intermediates in the ubiquitous glycosylation reaction. In this Review, we present more intricate light-induced synthetic strategies to modify native carbohydrates through homolytic C-H and C-C bond cleavage. These strategies allow access to glycans and glycoconjugates with profoundly altered carbohydrate skeletons, which are challenging to obtain through conventional synthetic means. Carbohydrate derivatives with such structural motifs represent a broad class of natural products integral to numerous biochemical processes and can be found in active pharmaceutical substances. Here we present progress made in C-H and C-C bond activation of carbohydrates through photoredox catalysis, focusing on the operational mechanisms and the scope of the described methodologies.
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3
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Santana AG, Herrera AJ, González CC. Intramolecular Metal-Free C(sp 3)-H Activation Enables a Selective Mono O-Debenzylation of Fully Protected Aminosugars. J Org Chem 2021; 86:16736-16752. [PMID: 34807601 DOI: 10.1021/acs.joc.1c01977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Carbamate-bearing benzylated aminosugars undergo an I2/I(III)-promoted intramolecular hydrogen atom transfer (IHAT) followed by a nucleophilic attack to provide polycyclic structures. Thus, suitably positioned benzyl ethers are surgically oxidized into the corresponding mixed N/O-benzylidene acetals, which can be conveniently deprotected under mild acidic conditions to grant access to selectively O-deprotected aminosugars amenable for further derivatization. The scope of this strategy has been proven with a series of furanosic and pyranosic scaffolds. Preliminary mechanistic studies, including Hammett LFER and KIE analyses, support a reaction pathway with nucleophilic cyclization as the rate-determining step.
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Affiliation(s)
- Andrés G Santana
- Instituto de Productos Naturales y Agrobiología del C.S.I.C., Avenida Astrofísico Francisco Sánchez 3, 38206 La Laguna, Tenerife, Spain
| | - Antonio J Herrera
- Instituto de Productos Naturales y Agrobiología del C.S.I.C., Avenida Astrofísico Francisco Sánchez 3, 38206 La Laguna, Tenerife, Spain
| | - Concepción C González
- Instituto de Productos Naturales y Agrobiología del C.S.I.C., Avenida Astrofísico Francisco Sánchez 3, 38206 La Laguna, Tenerife, Spain
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Santana AG, González CC. Tandem Radical Fragmentation/Cyclization of Guanidinylated Monosaccharides Grants Access to Medium-Sized Polyhydroxylated Heterocycles. Org Lett 2020; 22:8492-8495. [PMID: 33074675 DOI: 10.1021/acs.orglett.0c03091] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The fragmentation of anomeric alkoxyl radicals (ARF) and the subsequent cyclization promoted by hypervalent iodine provide an excellent method for the synthesis of guanidino-sugars. The methodology described herein is one of the few existing general methodologies for the formation of medium-sized exo- and endoguanidine-containing heterocycles presenting a high degree of oxygenation in their structure.
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Affiliation(s)
- Andrés G Santana
- Instituto de Productos Naturales y Agrobiología del C.S.I.C., Avenida Astrofísico Francisco Sánchez 3, 38206 La Laguna, Tenerife, Spain
| | - Concepción C González
- Instituto de Productos Naturales y Agrobiología del C.S.I.C., Avenida Astrofísico Francisco Sánchez 3, 38206 La Laguna, Tenerife, Spain
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Hernández-Guerra D, Kennedy AR, León EI, Martín Á, Pérez-Martín I, Rodríguez MS, Suárez E. Synthetic Approaches to Phosphasugars (2-oxo-1,2-oxaphosphacyclanes) Using the Anomeric Alkoxyl Radical β-Fragmentation Reaction as the Key Step. J Org Chem 2020; 85:4861-4880. [PMID: 32174121 DOI: 10.1021/acs.joc.0c00059] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The anomeric alkoxyl radical β-fragmentation (ARF) of carbohydrates possessing an electron-withdrawing group (EWG) at C2, promoted by PhI(OAc)2/I2, gives rise to an acyclic iodide through which a pentavalent atom of phosphorus can be introduced via the Arbuzov reaction. After selective hydrolysis and subsequent cyclization, the phosphonate or phosphinate intermediates can be converted into 2-deoxy-1-phosphahexopyranose and 2-deoxy-1-phosphapentopyranose sugars. The ARF of carbohydrates with an electron-donor group (EDG) at C2 proceeds by a radical-polar crossover mechanism, and the cyclization occurs by nucleophilic attack of a conveniently positioned phosphonate or phosphinate group to the transient oxocarbenium ion. This alternative methodology leads to 5-phosphasugars with a 4-deoxy-5-phosphapentopyranose framework. The structure and conformation of the 2-oxo-1,2-oxaphosphinane and 2-oxo-1,2-oxaphospholane ring systems in different carbohydrate models have been studied by NMR and X-ray crystallography.
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Affiliation(s)
- Daniel Hernández-Guerra
- Sı́ntesis de Productos Naturales, Instituto de Productos Naturales y Agrobiologı́a del CSIC, Carretera de La Esperanza 3, 38206, La Laguna, Tenerife, Spain
| | - Alan R Kennedy
- WestCHEM Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow G1 1XL, Scotland, U.K
| | - Elisa I León
- Sı́ntesis de Productos Naturales, Instituto de Productos Naturales y Agrobiologı́a del CSIC, Carretera de La Esperanza 3, 38206, La Laguna, Tenerife, Spain
| | - Ángeles Martín
- Sı́ntesis de Productos Naturales, Instituto de Productos Naturales y Agrobiologı́a del CSIC, Carretera de La Esperanza 3, 38206, La Laguna, Tenerife, Spain
| | - Inés Pérez-Martín
- Sı́ntesis de Productos Naturales, Instituto de Productos Naturales y Agrobiologı́a del CSIC, Carretera de La Esperanza 3, 38206, La Laguna, Tenerife, Spain
| | - María S Rodríguez
- Sı́ntesis de Productos Naturales, Instituto de Productos Naturales y Agrobiologı́a del CSIC, Carretera de La Esperanza 3, 38206, La Laguna, Tenerife, Spain
| | - Ernesto Suárez
- Sı́ntesis de Productos Naturales, Instituto de Productos Naturales y Agrobiologı́a del CSIC, Carretera de La Esperanza 3, 38206, La Laguna, Tenerife, Spain
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Abstract
Radical reactions have found many applications in carbohydrate chemistry, especially in the construction of carbon–carbon bonds. The formation of carbon–heteroatom bonds has been less intensively studied. This mini-review will summarize the efforts to add heteroatom radicals to unsaturated carbohydrates like endo-glycals. Starting from early examples, developed more than 50 years ago, the importance of such reactions for carbohydrate chemistry and recent applications will be discussed. After a short introduction, the mini-review is divided in sub-chapters according to the heteroatoms halogen, nitrogen, phosphorus, and sulfur. The mechanisms of radical generation by chemical or photochemical processes and the subsequent reactions of the radicals at the 1-position will be discussed. This mini-review cannot cover all aspects of heteroatom-centered radicals in carbohydrate chemistry, but should provide an overview of the various strategies and future perspectives.
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Ren H, Song JR, Li ZY, Pan WD. Oxazoline-/Copper-Catalyzed Alkoxyl Radical Generation: Solvent-Switched to Access 3a,3a'-Bisfuroindoline and 3-Alkoxyl Furoindoline. Org Lett 2019; 21:6774-6778. [PMID: 31398055 DOI: 10.1021/acs.orglett.9b02394] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
We report the first example of oxazoline-/copper-catalyzed alcohol oxidation to generate the alkoxyl radical under additive-free conditions. The resulting alkoxyl radical addition to alkene enables useful C-O bond-forming and selective C(sp3)-C(sp3) radical-radical dimerization/radical-trapping reactions, providing direct access to the 3a,3a'-bisfuro[2,3-b]indoline scaffold for the first time and a wide range of 3-alkoxyl furoindolines with high efficiency.
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Affiliation(s)
- Hai Ren
- State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang 550014, China.,The Key Laboratory of Chemistry for Natural Products of Guizhou Province and Chinese Academy of Sciences/Guizhou Provincial Engineering Research Center for Natural Drugs, Guiyang 550014, China
| | - Jun-Rong Song
- State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang 550014, China.,The Key Laboratory of Chemistry for Natural Products of Guizhou Province and Chinese Academy of Sciences/Guizhou Provincial Engineering Research Center for Natural Drugs, Guiyang 550014, China
| | - Zhi-Yao Li
- State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang 550014, China.,The Key Laboratory of Chemistry for Natural Products of Guizhou Province and Chinese Academy of Sciences/Guizhou Provincial Engineering Research Center for Natural Drugs, Guiyang 550014, China
| | - Wei-Dong Pan
- State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang 550014, China.,The Key Laboratory of Chemistry for Natural Products of Guizhou Province and Chinese Academy of Sciences/Guizhou Provincial Engineering Research Center for Natural Drugs, Guiyang 550014, China
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André-Joyaux E, Santana AG, González CC. Synthesis of Chiral Polyhydroxylated Benzimidazoles by a Tandem Radical Fragmentation/Cyclization Reaction: A Straight Avenue to Fused Aromatic-Carbohydrate Hybrids. J Org Chem 2019; 84:506-515. [PMID: 30589268 DOI: 10.1021/acs.joc.8b01988] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The synthesis of benzimidazole-fused iminosugars through a tandem β-fragmentation-intramolecular cyclization reaction is described. The use of the benzimidazole ring as the internal nucleophile and the use of phenyliodosophthalate (PhI(Phth)), a new metal-free and low toxic hypervalent iodine reagent, are the most remarkable novelties of this synthetic strategy. With this approach, we have demonstrated the usefulness of the fragmentation of anomeric alkoxyl radicals promoted by the PhI(Phth)/I2 system for the preparation of new compounds with potential interest for both medicinal and synthetic chemists.
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Affiliation(s)
- Emy André-Joyaux
- Instituto de Productos Naturales y Agrobiología del C.S.I.C. , Avenida Astrofísico Francisco Sánchez 3 , 38206 La Laguna , Tenerife , Spain
| | - Andrés G Santana
- Instituto de Productos Naturales y Agrobiología del C.S.I.C. , Avenida Astrofísico Francisco Sánchez 3 , 38206 La Laguna , Tenerife , Spain
| | - Concepción C González
- Instituto de Productos Naturales y Agrobiología del C.S.I.C. , Avenida Astrofísico Francisco Sánchez 3 , 38206 La Laguna , Tenerife , Spain
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Wang J, Huang B, Shi C, Yang C, Xia W. Visible-Light-Mediated Ring-Opening Strategy for the Regiospecific Allylation/Formylation of Cycloalkanols. J Org Chem 2018; 83:9696-9706. [PMID: 30067027 DOI: 10.1021/acs.joc.8b01225] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Here we describe a straightforward and efficient approach for regiospecific introduction of an allyl group into cycloalkanol molecules employing a visible-light-mediated ring-opening strategy. A wide range of distally allylated or formylated ketones is furnished from 1-aryl cycloalkanol precursors of variable ring sizes, providing a concise and practical access for the modification of complex natural products. Preliminary mechanistic studies demonstrate that the key O-centered radicals mediate the sequential ring cleavage and allylation/formylation.
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Affiliation(s)
- Junlei Wang
- State Key Lab of Urban Water Resource and Environment , Harbin Institute of Technology (Shenzhen) , Shenzhen 518055 , China
| | - Binbin Huang
- State Key Lab of Urban Water Resource and Environment , Harbin Institute of Technology (Shenzhen) , Shenzhen 518055 , China
| | - Chengcheng Shi
- State Key Lab of Urban Water Resource and Environment , Harbin Institute of Technology (Shenzhen) , Shenzhen 518055 , China
| | - Chao Yang
- State Key Lab of Urban Water Resource and Environment , Harbin Institute of Technology (Shenzhen) , Shenzhen 518055 , China
| | - Wujiong Xia
- State Key Lab of Urban Water Resource and Environment , Harbin Institute of Technology (Shenzhen) , Shenzhen 518055 , China
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Jia K, Li J, Chen Y. Selective P-C(sp 3 ) Bond Cleavage and Radical Alkynylation of α-Phosphorus Alcohols by Photoredox Catalysis. Chemistry 2018; 24:3174-3177. [PMID: 29356137 DOI: 10.1002/chem.201800202] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Indexed: 11/10/2022]
Abstract
Herein the first P-C(sp3 ) bond cleavage and radical alkynylation of α-phosphorus alcohols to construct phosphonoalkynes is reported. The phosphorus radical is generated upon P-C bond cleavage reaction via the alkoxyl radical through photoredox catalysis with cyclic iodine(III) reagents. Various arylphosphinoyl-, alkylphosphinoyl-, phosphonate-, and phosphonic amide alcohols serve as radical phosphorus precursors to construct phosphonoalkynes for the first time.
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Affiliation(s)
- Kunfang Jia
- State Key Laboratory of Bioorganic and Natural Products Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai, 200032, P. R. China
| | - Junzhao Li
- State Key Laboratory of Bioorganic and Natural Products Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai, 200032, P. R. China
| | - Yiyun Chen
- State Key Laboratory of Bioorganic and Natural Products Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai, 200032, P. R. China
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Berton JKET, Heugebaert TSA, Virieux D, Stevens CV. Fifty Years of (Benz)oxaphospholene Chemistry. Chemistry 2017; 23:17413-17431. [DOI: 10.1002/chem.201703129] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Indexed: 01/01/2023]
Affiliation(s)
- Jan K. E. T. Berton
- SynBioC Research Group, Department of Sustainable Organic Chemistry and Technology, Faculty of Bioscience Engineering; Ghent University; Coupure Links 653 9000 Ghent Belgium
- AM2N, Institut Charles Gerhardt, UMR 5253; Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM); 8, rue de l'Ecole Normale 34296 Montpellier France
| | - Thomas S. A. Heugebaert
- SynBioC Research Group, Department of Sustainable Organic Chemistry and Technology, Faculty of Bioscience Engineering; Ghent University; Coupure Links 653 9000 Ghent Belgium
| | - David Virieux
- AM2N, Institut Charles Gerhardt, UMR 5253; Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM); 8, rue de l'Ecole Normale 34296 Montpellier France
| | - Christian V. Stevens
- SynBioC Research Group, Department of Sustainable Organic Chemistry and Technology, Faculty of Bioscience Engineering; Ghent University; Coupure Links 653 9000 Ghent Belgium
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12
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Jia K, Zhang F, Huang H, Chen Y. Visible-Light-Induced Alkoxyl Radical Generation Enables Selective C(sp(3))-C(sp(3)) Bond Cleavage and Functionalizations. J Am Chem Soc 2016; 138:1514-7. [PMID: 26829105 DOI: 10.1021/jacs.5b13066] [Citation(s) in RCA: 203] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The alkoxyl radical is an important reactive intermediate in mechanistic studies and organic synthesis; however, its current generation from alcohol oxidation heavily relies on transition metal activation under strong oxidative conditions. Here we report the first visible-light-induced alcohol oxidation to generate alkoxyl radicals by cyclic iodine(III) reagent catalysis under mild reaction conditions. The β-fragmentation of alkoxyl radicals enables selective C(sp(3))-C(sp(3)) bond cleavage and alkynylation/alkenylation reactions with various strained cycloalkanols, and for the first time with linear alcohols.
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Affiliation(s)
- Kunfang Jia
- State Key Laboratory of Bioorganic and Natural Products Chemistry, Collaborative Innovation Center of Chemistry for Life Sciences, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences , 345 Lingling Road, Shanghai 200032, China
| | - Fuyuan Zhang
- School of Physical Science and Technology, Shanghai Tech University , 100 Haike Road, Shanghai 201210, China
| | - Hanchu Huang
- State Key Laboratory of Bioorganic and Natural Products Chemistry, Collaborative Innovation Center of Chemistry for Life Sciences, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences , 345 Lingling Road, Shanghai 200032, China
| | - Yiyun Chen
- State Key Laboratory of Bioorganic and Natural Products Chemistry, Collaborative Innovation Center of Chemistry for Life Sciences, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences , 345 Lingling Road, Shanghai 200032, China.,School of Physical Science and Technology, Shanghai Tech University , 100 Haike Road, Shanghai 201210, China
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