1
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Quiclet-Sire B, Zard SZ. Some Aspects of α-(Acyloxy)alkyl Radicals in Organic Synthesis. Molecules 2023; 28:7561. [PMID: 38005282 PMCID: PMC10673534 DOI: 10.3390/molecules28227561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Revised: 11/08/2023] [Accepted: 11/10/2023] [Indexed: 11/26/2023] Open
Abstract
The preparation and use of α-(acyloxy)alkyl xanthates to generate and capture α-(acyloxy)alkyl radicals is briefly reviewed. Their inter- and intramolecular additions to both activated and unactivated, electronically unbiased, alkenes, and to (hetero)aromatic rings, as well as their radical allylation and vinylation reactions are described. Application to the total synthesis of two 4-hydroxytetralone natural products is also presented.
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Affiliation(s)
| | - Samir Z. Zard
- Laboratoire de Synthèse Organique associé au C.N.R.S., UMR 7652, Ecole Polytechnique, 91128 Palaiseau, France;
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2
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Qiao H, Michalland J, Huang Q, Zard SZ. A Versatile Route to Acyl (MIDA)Boronates. Chemistry 2023; 29:e202302235. [PMID: 37477346 DOI: 10.1002/chem.202302235] [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: 07/18/2023] [Revised: 07/21/2023] [Accepted: 07/21/2023] [Indexed: 07/22/2023]
Abstract
A modular approach to highly functional acyl (MIDA)boronates is described. It involves the generation of the hitherto unknown radical derived from acetyl (MIDA)boronate and its capture by various alkenes, including electronically unbiased, unactivated alkenes. In contrast to the anion of acetyl (MIDA)boronate, which has not so far been employed in synthesis, the corresponding radical is well behaved and readily produced from the novel α-xanthyl acetyl (MIDA)boronate. This shelf-stable, easily prepared solid is a convenient acyl (MIDA)boronate transfer agent that provides a direct entry to numerous otherwise inaccessible structures, including latent 1,4-dicarbonyl derivatives that can be transformed into B(MIDA) substituted pyrroles and furans. A competition experiment indicated the acyl (MIDA)boronate substituted radical to be more stable than the all-carbon acetonyl radical but somewhat less reactive in additions to alkenes.
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Affiliation(s)
- Hui Qiao
- Laboratoire de Synthèse Organique, CNRS UMR 7652, Ecole polytechnique, 91128, Palaiseau Cedex, France
| | - Jean Michalland
- Laboratoire de Synthèse Organique, CNRS UMR 7652, Ecole polytechnique, 91128, Palaiseau Cedex, France
| | - Qi Huang
- Laboratoire de Synthèse Organique, CNRS UMR 7652, Ecole polytechnique, 91128, Palaiseau Cedex, France
| | - Samir Z Zard
- Laboratoire de Synthèse Organique, CNRS UMR 7652, Ecole polytechnique, 91128, Palaiseau Cedex, France
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3
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Zard SZ. Sulfur chemistry in action. New perspectives for organic synthesis. PHOSPHORUS SULFUR 2023. [DOI: 10.1080/10426507.2023.2173755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- Samir Z. Zard
- Laboratoire de Synthèse Organique associé au C. N. R. S., UMR 7652, Ecole Polytechnique, Palaiseau, France
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4
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Quiclet-Sire B, Zard SZ. The xanthate route to tetralones, tetralins, and naphthalenes. A brief account. Org Biomol Chem 2023; 21:910-924. [PMID: 36607600 DOI: 10.1039/d2ob02159e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The present account summarises routes to tetralones, tetralines, and naphthalenes based on the chemistry of xanthates developed in the authors' laboratory. The degenerative reversible transfer of xanthates allows radical addition even to unactivated, electronically unbiased alkenes, and tolerates a broad range of functional groups, in particular common polar groups such as esters, ketones, nitriles, amides, carbamates, etc. Xanthates also allow radical ring closures onto aromatic rings. This feature, in combination with the intermolecular addition to alkenes, can be used to construct tetralones and tetralines. With the appropriate appendages, the former can be converted into napthalenes with a variety of substitution patterns. This translates into a convergent approach to a vast array of building blocks of interest to the pharmaceutical and agrochemical industries, and to material sciences.
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Affiliation(s)
- Béatrice Quiclet-Sire
- Laboratoire de Synthèse Organique UMR 7652, Ecole Polytechnique, 91128 Palaiseau, France.
| | - Samir Z Zard
- Laboratoire de Synthèse Organique UMR 7652, Ecole Polytechnique, 91128 Palaiseau, France.
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5
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Boyer C, Kamigaito M, Satoh K, Moad G. Radical-Promoted Single-unit Monomer Insertion (SUMI) [aka. Reversible-Deactivation Radical Addition (RDRA)]. Prog Polym Sci 2023. [DOI: 10.1016/j.progpolymsci.2023.101648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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6
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Bieszczad B, Chen X, Zard SZ. An Ionic-Radical Approach to Vicinally Functionalized Cyclopentanones and Cyclohexanones. Org Lett 2022; 24:9370-9374. [PMID: 36534058 DOI: 10.1021/acs.orglett.2c03671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
A versatile strategy to access vicinally functionalized cyclopentanones and cyclohexanones is described. It takes advantage of new reagents, α-xanthyl enones, which can be prepared from the reaction of xanthate salts with the corresponding epoxyketones under mild conditions. β-Functionalization of these compounds can be performed by conjugate additions without affecting the xanthate moiety. This significantly expands the pool of xanthate substrates, allowing the synthesis of open chain and fused bicyclic building blocks useful in the synthesis of natural products.
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Affiliation(s)
- Bartosz Bieszczad
- Laboratoire de Synthèse Organique, CNRS UMR 7652, Ecole Polytechnique, Palaiseau Cedex 91128 Cedex, France
| | - Xuan Chen
- Laboratoire de Synthèse Organique, CNRS UMR 7652, Ecole Polytechnique, Palaiseau Cedex 91128 Cedex, France
| | - Samir Z Zard
- Laboratoire de Synthèse Organique, CNRS UMR 7652, Ecole Polytechnique, Palaiseau Cedex 91128 Cedex, France
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7
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Mistry S, Kumar R, Lister A, Gaunt MJ. C(sp 3)-C(sp 3) coupling of non-activated alkyl-iodides with electron-deficient alkenes via visible-light/silane-mediated alkyl-radical formation. Chem Sci 2022; 13:13241-13247. [PMID: 36425511 PMCID: PMC9667957 DOI: 10.1039/d2sc03516b] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Accepted: 10/27/2022] [Indexed: 08/24/2023] Open
Abstract
Here, we present a remarkably mild and general initiation protocol for alkyl-radical generation from non-activated alkyl-iodides. An interaction between a silane and an alkyl iodide is excited by irradiation with visible light to trigger carbon-iodide bond homolysis and form the alkyl radical. We show how this method can be developed into an operationally simple and general Giese addition reaction that can tolerate a range of sensitive functionalities not normally explored in established approaches to this strategically important transformation. The new method requires no photocatalyst or other additives and uses only commerical tris(trimethylsilyl)silane and visible light to effectively combine a broad range of alkyl halides with activated alkenes to form C(sp3)-C(sp3) bonds embedded within complex frameworks.
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Affiliation(s)
- Sanesh Mistry
- Yusuf Hamied Department of Chemistry, University of Cambridge Lensfield Road Cambridge CB2 1EW UK
| | - Roopender Kumar
- Yusuf Hamied Department of Chemistry, University of Cambridge Lensfield Road Cambridge CB2 1EW UK
| | | | - Matthew J Gaunt
- Yusuf Hamied Department of Chemistry, University of Cambridge Lensfield Road Cambridge CB2 1EW UK
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8
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Pseudo-glycoconjugates with a C-glycoside linkage. Adv Carbohydr Chem Biochem 2022; 82:35-77. [PMID: 36470649 DOI: 10.1016/bs.accb.2022.10.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Work by the author and colleagues has been focused on the development of pseudo-glycans (pseudo-glycoconjugates), in which the O-glycosidic linkage of the natural-type glycan structure is replaced by a C-glycosidic linkage. These analogs are not degraded by cellular glycoside hydrolases and are thus expected to be useful molecular tools that may maintain the original biological activity for a long period in the cell. However, their biological potential is not yet well understood because only a few pseudo glycans have so far been synthesized. This article aims to provide a bird's-eye view of our recent studies on the creation of C-glycoside analogs of ganglioside GM3 based on the CHF-sialoside linkage, and summarizes the chemical insights acquired during our stereoselective synthesis of the C-sialoside bond, ultimately leading to pseudo-GM3. Conformational analysis of the synthesized CHF-sialoside disaccharides confirmed that the anticipated conformational control by F-atom introduction was successful, and furthermore, enhanced the biological activity. In order to improve access to C-glycoside analogs based on pseudo-GM3, it is still important to streamline the synthesis process. With this in mind, we designed and developed a direct C-glycosylation method using atom-transfer radical coupling, and employed it in syntheses of pseudo-isomaltose and pseudo-KRN7000.
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9
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Abstract
A versatile strategy for the α-substitution of enones through the formal fusion between enones and unactivated alkenes is described. It relies on the formation and use of α-xanthyl-β-hydroxy ketones, which can be considered as synthetic equivalents of the high energy and difficult to tame alkenyl radicals. The process, which can often be accomplished one-pot, could be extended in one case to an α,β-unsaturated ester.
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Affiliation(s)
- Bartosz Bieszczad
- Laboratoire de Synthèse Organique, CNRS UMR 7652, Ecole Polytechnique, 91128 Palaiseau Cedex, France
| | - Samir Z Zard
- Laboratoire de Synthèse Organique, CNRS UMR 7652, Ecole Polytechnique, 91128 Palaiseau Cedex, France
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10
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Zeng X, Zard SZ. A Convergent Approach to 1,3-Dithiolan-2-ones and an Unexpected Synthesis of Lactones. Org Lett 2022; 24:5245-5248. [PMID: 35861650 DOI: 10.1021/acs.orglett.2c02215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A convergent route to 1,3-dithiolan-2-ones based on the radical addition of xanthates to allylic acetates is described. The process is modular, uses inexpensive starting materials and reagents, and is atom economical, since both sulfur atoms of the xanthate end up in the products. With adducts derived from xanthates bearing an ester group, an unexpected transformation leading to lactones was uncovered.
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Affiliation(s)
- Xianzhu Zeng
- Laboratoire de Synthèse Organique, CNRS UMR 7652 Ecole Polytechnique, 91128 Palaiseau, Cedex, France
| | - Samir Z Zard
- Laboratoire de Synthèse Organique, CNRS UMR 7652 Ecole Polytechnique, 91128 Palaiseau, Cedex, France
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11
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Zard SZ. The xanthate route to six-membered carbocycles. JOURNAL OF CHEMICAL RESEARCH 2022. [DOI: 10.1177/17475198221088194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Convergent routes to various six-membered carbocyclic architectures exploiting the unique radical chemistry of xanthates are described in this brief review. Three approaches are discussed. The first is the modification of existing cyclohexane building blocks, namely, cyclohexanones, cyclohexenones and cyclohexenes. The second deals with the construction of six-membered carbocycles by associating the chemistry of xanthates with classical ionic reactions, especially the Robinson annulation, the Michael addition and the Horner–Wadsworth–Emmons condensation. Finally, the third route is the formation of six-membered rings by direct six- exo and, but more rarely, six- endo cyclisation modes. Many of the complex structures presented herein would be tedious to obtain by more traditional methods.
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Affiliation(s)
- Samir Z Zard
- Laboratoire de Synthèse Organique associé au C. N. R. S., UMR 7652, Ecole Polytechnique, Palaiseau, France
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12
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Dorokhov VS, Quiclet-Sire B, Zard SZ. A Route to 5,5-Dithiospiroketals and to Long-Chain Monomers from the Biomass. Org Lett 2022; 24:2878-2882. [DOI: 10.1021/acs.orglett.2c00855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Valentin S. Dorokhov
- Laboratoire de Synthèse Organique, CNRS UMR 7652 Ecole Polytechnique, 91128 Cedex Palaiseau, France
| | - Béatrice Quiclet-Sire
- Laboratoire de Synthèse Organique, CNRS UMR 7652 Ecole Polytechnique, 91128 Cedex Palaiseau, France
| | - Samir Z. Zard
- Laboratoire de Synthèse Organique, CNRS UMR 7652 Ecole Polytechnique, 91128 Cedex Palaiseau, France
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13
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Michalland J, Casaretto N, Zard SZ. A Modular Access to 1,2‐ and 1,3‐Disubstituted Cyclobutylboronic Esters by Consecutive Radical Additions. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202113333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Jean Michalland
- Laboratoire de Synthèse Organique CNRS UMR 7652 Ecole polytechnique 91128 Palaiseau Cedex France
| | - Nicolas Casaretto
- Laboratoire de Chimie Moleculaire CNRS UMR 9168 Ecole polytechnique 91128 Palaiseau Cedex France
| | - Samir Z. Zard
- Laboratoire de Synthèse Organique CNRS UMR 7652 Ecole polytechnique 91128 Palaiseau Cedex France
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14
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Bingham NM, Abousalman-Rezvani Z, Collins K, Roth PJ. Thiocarbonyl Chemistry in Polymer Science. Polym Chem 2022. [DOI: 10.1039/d2py00050d] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Organised by reaction type, this review highlights the unique reactivity of thiocarbonyl (C=S) groups with radicals, anions, nucleophiles, electrophiles, in pericyclic reactions, and in the presence of light. In the...
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15
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Z. Zard S, Quiclet-Sire B. The Xanthate Route to Benzazepinones and Their Aza Congeners. HETEROCYCLES 2022. [DOI: 10.3987/rev-22-sr(r)9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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16
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Li H, Liu Y, Chiba S. Leveraging of Sulfur Anions in Photoinduced Molecular Transformations. JACS AU 2021; 1:2121-2129. [PMID: 34977884 PMCID: PMC8715496 DOI: 10.1021/jacsau.1c00363] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Indexed: 05/25/2023]
Abstract
This perspective describes recent advances in the use of sulfur anions to promote molecular transformations under irradiation with visible light. The topics are classified by the following reaction modes performed by the key sulfur anions: (1) C-S coupling via electron donor-acceptor (EDA) interactions, (2) photoinduced molecular transformation via sulfur anion EDA catalysis, (3) sulfur anions as photoredox and hydrogen atom transfer (HAT) catalysts, and 4) dithiocarbamate and xanthate as nucleophilic catalysts for photoinduced radical cascade reactions.
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Affiliation(s)
- Haoyu Li
- Division of Chemistry and
Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Yuliang Liu
- Division of Chemistry and
Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Shunsuke Chiba
- Division of Chemistry and
Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
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17
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Rieder S, Meléndez C, Dénès F, Jangra H, Mulliri K, Zipse H, Renaud P. Radical chain monoalkylation of pyridines. Chem Sci 2021; 12:15362-15373. [PMID: 34976357 PMCID: PMC8635225 DOI: 10.1039/d1sc02748d] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 10/21/2021] [Indexed: 12/27/2022] Open
Abstract
The monoalkylation of N-methoxypyridinium salts with alkyl radicals generated from alkenes (via hydroboration with catecholborane), alkyl iodides (via iodine atom transfer) and xanthates is reported. The reaction proceeds under neutral conditions since no acid is needed to activate the heterocycle and no external oxidant is required. A rate constant for the addition of a primary radical to N-methoxylepidinium >107 M-1 s-1 was experimentally determined. This rate constant is more than one order of magnitude larger than the one measured for the addition of primary alkyl radicals to protonated lepidine demonstrating the remarkable reactivity of methoxypyridinium salts towards radicals. The reaction has been used for the preparation of unique pyridinylated terpenoids and was extended to a three-component carbopyridinylation of electron-rich alkenes including enol esters, enol ethers and enamides.
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Affiliation(s)
- Samuel Rieder
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern Freiestrasse 3 CH-3012 Bern Switzerland
| | - Camilo Meléndez
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern Freiestrasse 3 CH-3012 Bern Switzerland
| | - Fabrice Dénès
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern Freiestrasse 3 CH-3012 Bern Switzerland
| | - Harish Jangra
- Department of Chemistry, LMU München Butenandtstrasse 5-13 81377 München Germany
| | - Kleni Mulliri
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern Freiestrasse 3 CH-3012 Bern Switzerland
| | - Hendrik Zipse
- Department of Chemistry, LMU München Butenandtstrasse 5-13 81377 München Germany
| | - Philippe Renaud
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern Freiestrasse 3 CH-3012 Bern Switzerland
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18
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Michalland J, Casaretto N, Zard SZ. A Modular Access to 1,2- and 1,3-Disubstituted Cyclobutylboronic Esters by Consecutive Radical Additions. Angew Chem Int Ed Engl 2021; 61:e202113333. [PMID: 34716652 DOI: 10.1002/anie.202113333] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Indexed: 01/22/2023]
Abstract
A modular approach to substituted cyclobutylboronic esters is described. It proceeds by successive intermolecular radical additions of xanthates to pinacolato 1-cyclobutenylboronate and to pinacolato bicyclo[1.1.0]but-1-ylboronate. Success hinges on tuning the stability of the α-boryl radical by exploiting the stabilizing influence of the trivalent boronic ester and the slightly destabilizing cyclobutane, which increases the σ-character of the radical. Reductive removal of the xanthate group finally provides a range of 1,2- and 1,3-disubstituted cyclobutylboronic esters. The contrast with cyclopropylboronic esters is striking, since the strong destabilization by the highly strained cyclopropane ring allows the first radical addition to take place but not the second. Furthermore, the first adducts are geminal xanthyl boronic esters that can be converted into cyclobutanones. This chemistry furnishes cyclobutylboronic esters that would be quite difficult to obtain otherwise and thus complements existing methods.
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Affiliation(s)
- Jean Michalland
- Laboratoire de Synthèse Organique, CNRS UMR 7652, Ecole polytechnique, 91128, Palaiseau Cedex, France
| | - Nicolas Casaretto
- Laboratoire de Chimie Moleculaire, CNRS UMR 9168, Ecole polytechnique, 91128, Palaiseau Cedex, France
| | - Samir Z Zard
- Laboratoire de Synthèse Organique, CNRS UMR 7652, Ecole polytechnique, 91128, Palaiseau Cedex, France
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19
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Michalland J, Zard SZ. A Convergent, Stereoselective Route to Trisubstituted Alkenyl Boronates. Org Lett 2021; 23:8018-8022. [PMID: 34617761 DOI: 10.1021/acs.orglett.1c03022] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
A modular, stereoselective route to trisubstituted (Z)-alkenyl (MIDA)boronates is described, consisting of the radical addition-fragmentation of dithiocarbonates to 2-(MIDA)boronyl-3-(2'-fluoro-pyridyl-6'-oxy)-alkenes. The bulky (MIDA)boronate ensures a highly stereoselective fragmentation that is enhanced by the poor stabilization of the radical adjacent to the tetravalent boron atom. The vinyl boronate precursors are prepared from propargyl alcohols by copper-catalyzed regioselective protoboration of their fluoropyridoxy derivatives, with the fluoropyridine acting as an internal directing group.
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Affiliation(s)
- Jean Michalland
- Laboratoire de Synthèse Organique, CNRS UMR 7652, Ecole Polytechnique, 91128 Palaiseau Cedex, France
| | - Samir Z Zard
- Laboratoire de Synthèse Organique, CNRS UMR 7652, Ecole Polytechnique, 91128 Palaiseau Cedex, France
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20
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Wang S, Wang H, König B. Light-Induced Single-Electron Transfer Processes involving Sulfur Anions as Catalysts. J Am Chem Soc 2021; 143:15530-15537. [PMID: 34542279 DOI: 10.1021/jacs.1c07785] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Photoredox catalysis has evolved as an attractive approach to enable a wide variety of chemical reactions with high selectivity under mild conditions. The development of novel photocatalytic systems is key to obtaining new reactivity and improving their catalytic performances. In this context, cost-effective organic anion-based photocatalysts have recently attracted increasing interest. In particular, sulfur-based anionic catalysts are of interest due to their unique redox properties. This Perspective highlights and discusses recent advances in light-induced single-electron-transfer processes directly involving sulfur anions as catalysts. The content of this Perspective is organized along the different photoinduced electron-transfer pathways between catalysts and substrates.
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Affiliation(s)
- Shun Wang
- Institute of Organic Chemistry, Faculty of Chemistry and Pharmacy, University of Regensburg, 93040 Regensburg, Germany
| | - Hua Wang
- Institute of Organic Chemistry, Faculty of Chemistry and Pharmacy, University of Regensburg, 93040 Regensburg, Germany
| | - Burkhard König
- Institute of Organic Chemistry, Faculty of Chemistry and Pharmacy, University of Regensburg, 93040 Regensburg, Germany
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21
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Riart-Ferrer X, Sang P, Tao J, Xu H, Jin LM, Lu H, Cui X, Wojtas L, Zhang XP. Metalloradical activation of carbonyl azides for enantioselective radical aziridination. Chem 2021; 7:1120-1134. [PMID: 33869888 DOI: 10.1016/j.chempr.2021.03.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Organic azides have been increasingly employed as nitrogen sources for catalytic olefine aziridination due to their ease of preparation and generation of benign N2 as the only byproduct. Among common organic azides, carbonyl azides have not been previously demonstrated as effective nitrogen sources for intermolecular olefin aziridination despite the synthetic utilities of N-carbonyl aziridines. As a new application of metalloradical catalysis, we have developed a catalytic system that can effectively employ the carbonyl azide TrocN3 for highly asymmetric aziridination of alkenes at room temperature. The resulting enantioenriched N-Trocaziridines have been shown as valuable chiral synthons for stereoselective synthesis of other chiral aziridines and various chiral amines. The Co(II)-based metalloradical system, which proceeds with distinctive stepwise radical mechanism, may provide a general method for asymmetric synthesis of chiral aziridines from alkenes with organic azides.
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Affiliation(s)
- Xavier Riart-Ferrer
- Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, MA 02467, USA
- These authors contributed equally
| | - Peng Sang
- Department of Chemistry, University of South Florida, Tampa, FL 33620, USA
- These authors contributed equally
| | - Jingran Tao
- Department of Chemistry, University of South Florida, Tampa, FL 33620, USA
- These authors contributed equally
| | - Hao Xu
- Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, MA 02467, USA
| | - Li-Mei Jin
- Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, MA 02467, USA
| | - Hongjian Lu
- Department of Chemistry, University of South Florida, Tampa, FL 33620, USA
| | - Xin Cui
- Department of Chemistry, University of South Florida, Tampa, FL 33620, USA
| | - Lukasz Wojtas
- Department of Chemistry, University of South Florida, Tampa, FL 33620, USA
| | - X Peter Zhang
- Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, MA 02467, USA
- Lead contact
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22
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23
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Affiliation(s)
- Nicholas D. C. Tappin
- University of Bern Department of Chemistry and Biochemistry Freiestrasse 3 3012 Bern Switzerland)
| | - Philippe Renaud
- University of Bern Department of Chemistry and Biochemistry Freiestrasse 3 3012 Bern Switzerland)
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Zard SZ. Discovery of the RAFT/MADIX Process: Mechanistic Insights and Polymer Chemistry Implications. Macromolecules 2020. [DOI: 10.1021/acs.macromol.0c01441] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Samir Z. Zard
- Laboratoire de Synthèse Organique Associé au CNRS, UMR 7652, Ecole Polytechnique, 91128 Palaiseau, France
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Affiliation(s)
- Lidong Cao
- University of BernDepartment of Chemistry and Biochemistry Freiestrasse 3 CH-3012 Bern Switzerland
- Institute of Plant ProtectionChinese Academy of Agricultural Sciences No. 2 Yuanmingyuan West Road, Haidian District Beijing 100193, P. R. of China
| | - Ciril Jimeno
- University of BernDepartment of Chemistry and Biochemistry Freiestrasse 3 CH-3012 Bern Switzerland
- Department of Biological ChemistryInstitute of Advanced Chemistry of Catalonia (IQAC-CSIC), Jordi Girona 18-26 E-08034 Barcelona Spain
| | - Philippe Renaud
- University of BernDepartment of Chemistry and Biochemistry Freiestrasse 3 CH-3012 Bern Switzerland
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Zard SZ. The Xanthate Route to Indolines, Indoles, and their Aza Congeners. Chemistry 2020; 26:12689-12705. [DOI: 10.1002/chem.202001341] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 04/17/2020] [Indexed: 12/25/2022]
Affiliation(s)
- Samir Z. Zard
- Laboratoire de Synthèse Organique, UMR 7652 Ecole Polytechnique 91128 Palaiseau France
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de Pedro Beato E, Mazzarella D, Balletti M, Melchiorre P. Photochemical generation of acyl and carbamoyl radicals using a nucleophilic organic catalyst: applications and mechanism thereof. Chem Sci 2020; 11:6312-6324. [PMID: 32953026 PMCID: PMC7472930 DOI: 10.1039/d0sc02313b] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 06/03/2020] [Indexed: 11/22/2022] Open
Abstract
An organic catalyst uses low-energy photons to generate acyl and carbamoyl radicals upon activation of the corresponding chlorides via a nucleophilic acyl substitution path. The synthetic potential and the mechanism of this strategy are discussed.
We detail a strategy that uses a commercially available nucleophilic organic catalyst to generate acyl and carbamoyl radicals upon activation of the corresponding chlorides and anhydrides via a nucleophilic acyl substitution path. The resulting nucleophilic radicals are then intercepted by a variety of electron-poor olefins in a Giese-type addition process. The chemistry requires low-energy photons (blue LEDs) to activate acyl and carbamoyl radical precursors, which, due to their high reduction potential, are not readily prone to redox-based activation mechanisms. To elucidate the key mechanistic aspects of this catalytic photochemical radical generation strategy, we used a combination of transient absorption spectroscopy investigations, electrochemical studies, quantum yield measurements, and the characterization of key intermediates. We identified a variety of off-the-cycle intermediates that engage in a light-regulated equilibrium with reactive radicals. These regulated equilibriums cooperate to control the overall concentrations of the radicals, contributing to the efficiency of the overall catalytic process and facilitating the turnover of the catalyst.
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Affiliation(s)
- Eduardo de Pedro Beato
- ICIQ - Institute of Chemical Research of Catalonia , The Barcelona Institute of Science and Technology , Avenida Països Catalans 16 , 43007 , Tarragona , Spain . ; http://www.iciq.org/research/research_group/prof-paolo-melchiorre/
| | - Daniele Mazzarella
- ICIQ - Institute of Chemical Research of Catalonia , The Barcelona Institute of Science and Technology , Avenida Països Catalans 16 , 43007 , Tarragona , Spain . ; http://www.iciq.org/research/research_group/prof-paolo-melchiorre/
| | - Matteo Balletti
- ICIQ - Institute of Chemical Research of Catalonia , The Barcelona Institute of Science and Technology , Avenida Països Catalans 16 , 43007 , Tarragona , Spain . ; http://www.iciq.org/research/research_group/prof-paolo-melchiorre/
| | - Paolo Melchiorre
- ICIQ - Institute of Chemical Research of Catalonia , The Barcelona Institute of Science and Technology , Avenida Països Catalans 16 , 43007 , Tarragona , Spain . ; http://www.iciq.org/research/research_group/prof-paolo-melchiorre/.,ICREA , Passeig Lluís Companys 23 , 08010 , Barcelona , Spain
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Chen X, Zard SZ. Convergent Route to β-Amino Acids and to β-Heteroarylethylamines: An Unexpected Vinylation Reaction. Org Lett 2020; 22:3628-3632. [PMID: 32314926 DOI: 10.1021/acs.orglett.0c01087] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Various protected β2-amino acids can be prepared by radical addition of β-phthalimido-α-xanthyl propionic acid, both as the free acid or as the ethyl ester. Successive radical additions provide access to more complex structures. In the case of the free acid, addition to certain heteroaromatics leads directly to β-heteroarylethylamines through spontaneous decarboxylation of the intermediate adduct. Forcing the decarboxylation in some cases generated a vinyl group by decarboxylative elimination of the phthalimido group.
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Affiliation(s)
- Xuan Chen
- Laboratoire de Synthèse Organique, CNRS UMR 7652 Ecole Polytechnique, 91128 Cedex Palaiseau, France
| | - Samir Z Zard
- Laboratoire de Synthèse Organique, CNRS UMR 7652 Ecole Polytechnique, 91128 Cedex Palaiseau, France
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Spinnato D, Schweitzer-Chaput B, Goti G, Ošeka M, Melchiorre P. A Photochemical Organocatalytic Strategy for the α-Alkylation of Ketones by using Radicals. Angew Chem Int Ed Engl 2020; 59:9485-9490. [PMID: 32053279 PMCID: PMC7317845 DOI: 10.1002/anie.201915814] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Indexed: 12/16/2022]
Abstract
Reported herein is a visible‐light‐mediated radical approach to the α‐alkylation of ketones. This method exploits the ability of a nucleophilic organocatalyst to generate radicals upon SN2‐based activation of alkyl halides and blue light irradiation. The resulting open‐shell intermediates are then intercepted by weakly nucleophilic silyl enol ethers, which would be unable to directly attack the alkyl halides through a traditional two‐electron path. The mild reaction conditions allowed functionalization of the α position of ketones with functional groups that are not compatible with classical anionic strategies. In addition, the redox‐neutral nature of this process makes it compatible with a cinchona‐based primary amine catalyst, which was used to develop a rare example of enantioselective organocatalytic radical α‐alkylation of ketones.
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Affiliation(s)
- Davide Spinnato
- ICIQ-Institute of Chemical Research of Catalonia the Barcelona Institute of Science and Technology, Avenida Països Catalans 16, 43007, Tarragona, Spain
| | - Bertrand Schweitzer-Chaput
- ICIQ-Institute of Chemical Research of Catalonia the Barcelona Institute of Science and Technology, Avenida Països Catalans 16, 43007, Tarragona, Spain
| | - Giulio Goti
- ICIQ-Institute of Chemical Research of Catalonia the Barcelona Institute of Science and Technology, Avenida Països Catalans 16, 43007, Tarragona, Spain
| | - Maksim Ošeka
- ICIQ-Institute of Chemical Research of Catalonia the Barcelona Institute of Science and Technology, Avenida Països Catalans 16, 43007, Tarragona, Spain
| | - Paolo Melchiorre
- ICIQ-Institute of Chemical Research of Catalonia the Barcelona Institute of Science and Technology, Avenida Països Catalans 16, 43007, Tarragona, Spain.,ICREA, Passeig Lluís Companys 23, 08010, Barcelona, Spain
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Spinnato D, Schweitzer‐Chaput B, Goti G, Ošeka M, Melchiorre P. A Photochemical Organocatalytic Strategy for the α‐Alkylation of Ketones by using Radicals. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201915814] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Davide Spinnato
- ICIQ—Institute of Chemical Research of Catalonia the Barcelona Institute of Science and Technology Avenida Països Catalans 16 43007 Tarragona Spain
| | - Bertrand Schweitzer‐Chaput
- ICIQ—Institute of Chemical Research of Catalonia the Barcelona Institute of Science and Technology Avenida Països Catalans 16 43007 Tarragona Spain
| | - Giulio Goti
- ICIQ—Institute of Chemical Research of Catalonia the Barcelona Institute of Science and Technology Avenida Països Catalans 16 43007 Tarragona Spain
| | - Maksim Ošeka
- ICIQ—Institute of Chemical Research of Catalonia the Barcelona Institute of Science and Technology Avenida Països Catalans 16 43007 Tarragona Spain
| | - Paolo Melchiorre
- ICIQ—Institute of Chemical Research of Catalonia the Barcelona Institute of Science and Technology Avenida Països Catalans 16 43007 Tarragona Spain
- ICREA Passeig Lluís Companys 23 08010 Barcelona Spain
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