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Peng Q, Hwang MU, Rentería-Gómez Á, Mukherjee P, Young RM, Qiu Y, Wasielewski MR, Gutierrez O, Scheidt KA. Photochemical phosphorus-enabled scaffold remodeling of carboxylic acids. Science 2024; 385:1471-1477. [PMID: 39325876 DOI: 10.1126/science.adr0771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2024] [Accepted: 08/27/2024] [Indexed: 09/28/2024]
Abstract
The excitation of carbonyl compounds by light to generate radical intermediates has historically been restricted to ketones and aldehydes; carboxylic acids have been overlooked because of high energy requirements and low quantum efficiency. A successful activation strategy would necessitate a bathochromic shift in the absorbance profile, an increase in triplet diradical lifetime, and ease of further functionalization. We present a single-flask transformation of carboxylic acids to acyl phosphonates that can access synthetically useful triplet diradicals under visible light or near-ultraviolet irradiation. The use of phosphorus circumvents unproductive Norrish type I processes, promoting selectivity that enables hydrogen-atom transfer reactivity. Use of this strategy promotes the efficient scaffold remodeling of carboxylic acids through various annulation, contraction, and expansion manifolds.
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Affiliation(s)
- Qiupeng Peng
- Department of Chemistry, Northwestern University, Evanston, IL 60208, USA
| | - Meemie U Hwang
- Department of Chemistry, Northwestern University, Evanston, IL 60208, USA
| | | | - Poulami Mukherjee
- Department of Chemistry, Texas A&M University, College Station, TX 77843, USA
| | - Ryan M Young
- Department of Chemistry, Northwestern University, Evanston, IL 60208, USA
- Paula M. Trienens Institute for Sustainability and Energy, Northwestern University, Evanston, IL 60208, USA
| | - Yunfan Qiu
- Department of Chemistry, Northwestern University, Evanston, IL 60208, USA
- Paula M. Trienens Institute for Sustainability and Energy, Northwestern University, Evanston, IL 60208, USA
| | - Michael R Wasielewski
- Department of Chemistry, Northwestern University, Evanston, IL 60208, USA
- Paula M. Trienens Institute for Sustainability and Energy, Northwestern University, Evanston, IL 60208, USA
| | - Osvaldo Gutierrez
- Department of Chemistry, Texas A&M University, College Station, TX 77843, USA
| | - Karl A Scheidt
- Department of Chemistry, Northwestern University, Evanston, IL 60208, USA
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2
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Graf S, Pesch H, Appleson T, Lei T, Breder A, Siewert I. Mechanistic Analysis Reveals Key Role of Interchalcogen Multicatalysis in Photo-Aerobic 3-Pyrroline Syntheses by Aza-Wacker Cyclizations. CHEMSUSCHEM 2024; 17:e202301518. [PMID: 38214219 DOI: 10.1002/cssc.202301518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 01/01/2024] [Accepted: 01/10/2024] [Indexed: 01/13/2024]
Abstract
A light-driven dual and ternary catalytic aza-Wacker protocol for the construction of 3-pyrrolines by partially disulfide-assisted selenium-π-acid multicatalysis is reported. A structurally diverse array of sulfonamides possessing homopolar mono-, di- and trisubstituted olefinic double bonds is selectively converted to the corresponding 3-pyrrolines in up to 95 % isolated yield and with good functional group tolerance. Advanced electrochemical mechanistic investigations of the protocol suggest a dual role of the disulfide co-catalyst. On the one hand, the disulfide serves as an electron hole shuttle between the excited photoredox catalyst and the selenium co-catalyst. On the other hand, the sulfur species engages in the final, product releasing step of the catalytic cycle by accelerating the β-elimination of the selenium moiety, which was found in many cases to lead to considerably improved product yields.
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Affiliation(s)
- Sebastian Graf
- Universität Regensburg, Institut für Organische Chemie, Universitätstrasse 31, 93053, Regensburg, Germany
| | - Henner Pesch
- Universität Göttingen, Institut für Anorganische Chemie, Tammannstrasse 4, 37077, Göttingen, Germany
| | - Theresa Appleson
- Universität Regensburg, Institut für Organische Chemie, Universitätstrasse 31, 93053, Regensburg, Germany
| | - Tao Lei
- Universität Regensburg, Institut für Organische Chemie, Universitätstrasse 31, 93053, Regensburg, Germany
| | - Alexander Breder
- Universität Regensburg, Institut für Organische Chemie, Universitätstrasse 31, 93053, Regensburg, Germany
| | - Inke Siewert
- Universität Göttingen, Institut für Anorganische Chemie, Tammannstrasse 4, 37077, Göttingen, Germany
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Abstract
Alkoxyallenes are easily available and versatile building blocks for the preparation
of a variety of natural products (terpenes, polyketides, alkaloids, amino acids, carbohydrates
etc.) originating from different classes. The synthetic use of the three allene carbon
atoms frequently follows the “normal” reactivity pattern showing that alkoxyallenes
can be regarded as special enol ethers. Additions of alcohols or amines to alkoxyallenes
form vinyl-substituted O,O- or N,O-acetals that are frequently used in ring-closing
metathesis reactions. This methodology delivers crucial heterocyclic units of the target
compounds. Enantioselective additions provide products with high enantiopurity.
Alternatively, an “Umpolung” of reactivity of alkoxyallenes is achieved by lithiation at
C-1 and subsequent reaction with electrophiles, such as alkyl halides, carbonyl
compounds, imines or nitrones. High stereoselectivity of the addition step can be achieved by substrate control
or auxiliary control. The high diastereo- or enantioselectivity is transferred to the subsequent acyclic or cyclic
products. The cyclization of primary addition products occurs efficiently under mild conditions and provides
functionalized dihydrofuran, dihydropyrrole or 1,2-oxazine derivatives. These are valuable intermediates for
the synthesis of a variety of heterocyclic natural products. Nazarov cyclizations or gold catalyzed rearrangements
allow the synthesis of five- and six-membered carbocyclic compounds that are also used for natural
product synthesis.
Dedicated to Dr. Reinhold Zimmer, a pioneer of alkoxyallene chemistry, on the occasion of his 60th
birthday.
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Affiliation(s)
- Volker Martin Schmiedel
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustr. 3, 14195 Berlin, Germany
| | - Hans-Ulrich Reissig
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustr. 3, 14195 Berlin, Germany
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4
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Medran NS, La-Venia A, Testero SA. Metal-mediated synthesis of pyrrolines. RSC Adv 2019; 9:6804-6844. [PMID: 35518475 PMCID: PMC9061060 DOI: 10.1039/c8ra10247c] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Accepted: 02/18/2019] [Indexed: 12/21/2022] Open
Abstract
The five-membered, nitrogen-containing pyrroline ring is a privileged structure. This ring is present in many bioactive compounds from natural sources. Pyrrolines-the dihydro derivatives of pyrroles-have three structural isomer classes, depending on the location of the double bond: 1-pyrrolines (3,4-dihydro-2H-pyrroles), 2-pyrrolines (2,3-dihydro-1H-pyrroles) and 3-pyrrolines (2,5-dihydro-1H-pyrroles). This review aims to describe the latest advances for the synthesis of pyrrolines by transition metal-catalyzed cyclizations. Only reactions in which the pyrroline ring is formed by metal promotion are described. Transformations of the pyrroline ring in other heterocycles, and the structural manipulations of the pyrroline itself are not discussed. The review is organized into three parts, each covering the metal-mediated synthesis of the three pyrroline isomers. Each part is subdivided according to the metal involved, and concludes with a brief description of notable biological activities within the class.
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Affiliation(s)
- Noelia S Medran
- Instituto de Química Rosario - IQUIR (CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario Suipacha 531 Rosario S2002LRK Argentina http://www.iquir-conicet.gov.ar/eng/
| | - Agustina La-Venia
- Instituto de Química Rosario - IQUIR (CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario Suipacha 531 Rosario S2002LRK Argentina http://www.iquir-conicet.gov.ar/eng/
| | - Sebastian A Testero
- Instituto de Química Rosario - IQUIR (CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario Suipacha 531 Rosario S2002LRK Argentina http://www.iquir-conicet.gov.ar/eng/
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Hausherr A, Siemeister G, Reissig HU. Alkoxyallene-based syntheses of preussin and its analogs and their cytotoxicity. Org Biomol Chem 2018; 17:122-134. [PMID: 30520931 DOI: 10.1039/c8ob02645a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Short syntheses of oxa-preussin, racemic preussin and (-)-preussin are reported. Starting from a racemic 3-nonyl-substituted methoxyallene derivative, its lithiation and addition to phenylethanal provided the corresponding allenyl alcohol that was converted into two diastereomeric dihydrofuran derivatives by silver nitrate-catalyzed 5-endo-trig cyclization. The acid hydrolysis of the enol ether moiety gave heterocyclic ketones and subsequent highly stereoselective reductions with l-selectride furnished 2-benzyl-5-nonylfuran-3-ol derivatives in good overall yield. The major all-cis-diastereomer has the skeleton and relative configuration of preussin and is hence called oxa-preussin. An analogous sequence with the same allene, but an N-sulfonyl imine as the electrophile, finally led to racemic preussin. The stereoselectivities of the individual steps are discussed in detail. With an enantiopure 2-benzyl-5-nonylpyrrolidin-3-one intermediate the preparation of (-)-preussin with an enantiomeric ratio of >95 : 5 could be accomplished in a few steps. The sign of the optical rotation of this product finally proved the absolute configurations of its precursors and demonstrated that our chiral auxiliary-based route led to the antipode of the natural product. The cytotoxicity of several of the prepared heterocycles against MCF-7 tumor cells was investigated and five compounds, including racemic and enantiopure (-)-preussin, were identified as highly cytotoxic with IC50 values in the range of 3-6 μM.
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Affiliation(s)
- Arndt Hausherr
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustr. 3, 14195 Berlin, Germany.
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