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Darnowski MG, Lanosky TD, Paquette AR, Boddy CN. Synthesis of a Constitutional Isomer of Armeniaspirol A, Pseudoarmeniaspirol A, via Lewis Acid-Mediated Rearrangement. J Org Chem 2022; 87:15634-15643. [PMID: 36322913 DOI: 10.1021/acs.joc.2c02331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The natural product armeniaspirol possesses a unique spirocyclic N,O-ketal in an α,β-dichloro-α,β-unsaturated lactam scaffold that has proved challenging to synthesize. Herein, we characterize the oxidative chlorination of pyrrole-2-carboxylate derivatives that rapidly generates this scaffold. The scope of this oxidation was extended to a series of esters and amides. Pyrrole-2-ketones could not be converted into the lactam due to an oxidative fragmentation. This result was unexpected since chloro-armeniaspirol has been synthesized via oxidative chlorination of a pyrrole-2-ketone. Examination of this successful oxidation showed that the desired scaffold was accessed due to intramolecular trapping from the neighboring free phenol, preventing fragmentation. Using the product of methyl N-methyl pyrrole-2-carboxylate oxidation 7b, we attempted to access the natural product armeniaspirol 2; however, an unanticipated Lewis acid-mediated rearrangement led to formation of a constitutional isomer, pseudoarmeniaspirol A 1. A small panel of pseudoarmeniaspirol analogues was synthesized and evaluated for antibiotic activity, inhibition of the targets of armeniaspirol, ClpXP and ClpYQ, and protonophore activity. While pseudoarmeniaspirol shows antibiotic activity, it does not target ClpXP or ClpYQ and has less protonophore activity than the natural product.
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Affiliation(s)
- Michael G Darnowski
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON K1N 6N5 Canada
| | - Taylor D Lanosky
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON K1N 6N5 Canada
| | - André R Paquette
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON K1N 6N5 Canada
| | - Christopher N Boddy
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, ON K1N 6N5 Canada
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2
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Torres P, Balcells M, Canela-Garayoa R. Effect of Novel Deep Eutectic Solvents on the Endo/Exo Ratio of Diels-Alder Reactions at Room Temperature. ACS OMEGA 2021; 6:19392-19399. [PMID: 34368526 PMCID: PMC8340089 DOI: 10.1021/acsomega.1c00980] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 05/31/2021] [Indexed: 06/13/2023]
Abstract
The Diels-Alder reaction is a prototypical example of a thermally allowed [4 + 2] cycloaddition with good control over the regio- and stereochemical outcomes. Therefore, Diels-Alder reactions in which adjacent stereocenters are generated at the two ends of the newly formed single bonds imply two different possible stereochemical outcomes. In cases where the dienophile has a single electron-withdrawing substituent, the outcome can often be predicted by applying the known "endo rule". Furthermore, the use of chiral eutectic solvents in asymmetric synthesis has become a novel tool to maintain sustainability in organic synthesis. In the present work, a set of recyclable and sustainable bio-based deep eutectic solvents (DESs) was designed using hydrogen bond acceptors (HBAs) with a chiral center. These compounds were used in their racemic and enantiomerically enriched forms to prepare DESs with lactic acid (LA), glycerol (Gly), and ethylene glycol, which act as hydrogen bond donors (HBDs) in the corresponding eutectic mixture. These DESs were used as solvents to study the reaction between cyclopentadiene and ethyl acrylate or butyl acrylate in typical [4 + 2] cycloadditions. The best yields and endo-selectivity were achieved using LA as the HBD in the eutectic mixtures. The results and adduct ratios obtained show that these DESs were able to improve both reaction yields and selectivity when compared to those observed in organic solvents or ionic liquids. Moreover, the reaction products (adducts) were easily recovered with diethyl ether from the reaction mixture, where they appeared as an upper layer.
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Huynh VN, Leitner M, Bhattacharyya A, Uhlstein L, Kreitmeier P, Sakrausky P, Rehbein J, Reiser O. Diels-Alder reactions and electrophilic substitutions with atypical regioselectivity enable functionalization of terminal rings of anthracene. Commun Chem 2020; 3:158. [PMID: 36703384 PMCID: PMC9814106 DOI: 10.1038/s42004-020-00407-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 10/07/2020] [Indexed: 01/29/2023] Open
Abstract
Reversing the regioselectivity of the renowned Diels-Alder reaction by overriding the usual thermodynamic and kinetic governing factors has always been a formidable challenge to synthetic organic chemists. Anthracenes are well-known to undergo [4 + 2]-cycloadditions with dienophiles at their 9,10-positions (central ring) over 1,4-positions (terminal ring) guided by the relative aromatic stabilization energy of the two possible products, and also by harboring the largest orbital coefficients of the highest occupied molecular orbital (HOMO) at the 9,10-positions. We, herein, report a 1,4-selective [4 + 2]-cycloaddition strategy of 9,10-unsubstituted anthracenes by installing electron-donating substituents on the terminal rings which is heretofore unprecedented to the best of our knowledge. The developed synthetic strategy does not require any premeditated engagement of the 9,10-positions either with any sterically bulky or electron-withdrawing substituents and allows delicate calibration of the regioselectivity by modulating the electron-donating strength of the substituents on the terminal rings. Likewise, the regioselective functionalization of the terminal anthracene ring in electrophilic substitution reactions is demonstrated. A mechanistic rationale is offered with the aid of detailed computational studies, and finally, synthetic applications are presented.
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Affiliation(s)
- Vinh Ngoc Huynh
- grid.7727.50000 0001 2190 5763Institut für Organische Chemie, Universität Regensburg, Universitätsstr. 31, 93053 Regensburg, Germany ,grid.454160.20000 0004 0642 8526University of Science, Vietnam National University, 227 Nguyễn Văn Cừ street, district 5, Ho Chi Minh City, Vietnam
| | - Michael Leitner
- grid.7727.50000 0001 2190 5763Institut für Organische Chemie, Universität Regensburg, Universitätsstr. 31, 93053 Regensburg, Germany
| | - Aditya Bhattacharyya
- grid.7727.50000 0001 2190 5763Institut für Organische Chemie, Universität Regensburg, Universitätsstr. 31, 93053 Regensburg, Germany
| | - Lisa Uhlstein
- grid.7727.50000 0001 2190 5763Institut für Organische Chemie, Universität Regensburg, Universitätsstr. 31, 93053 Regensburg, Germany
| | - Peter Kreitmeier
- grid.7727.50000 0001 2190 5763Institut für Organische Chemie, Universität Regensburg, Universitätsstr. 31, 93053 Regensburg, Germany
| | - Patrick Sakrausky
- grid.7727.50000 0001 2190 5763Institut für Organische Chemie, Universität Regensburg, Universitätsstr. 31, 93053 Regensburg, Germany
| | - Julia Rehbein
- grid.7727.50000 0001 2190 5763Institut für Organische Chemie, Universität Regensburg, Universitätsstr. 31, 93053 Regensburg, Germany
| | - Oliver Reiser
- grid.7727.50000 0001 2190 5763Institut für Organische Chemie, Universität Regensburg, Universitätsstr. 31, 93053 Regensburg, Germany
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Fused multifunctionalized bridge aromatic hydrocarbons from in situ-generated arynes and anthracene derivatives. CHINESE CHEM LETT 2020. [DOI: 10.1016/j.cclet.2019.10.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Xu WL, Zhang H, Hu YL, Yang H, Chen J, Zhou L. Metal-Free Dehydrogenative Diels-Alder Reactions of Prenyl Derivatives with Dienophiles via a Thermal Reversible Process. Org Lett 2018; 20:5774-5778. [PMID: 30182721 DOI: 10.1021/acs.orglett.8b02469] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
An efficient dehydrogenative Diels-Alder reaction of prenyl derivatives with dienophiles has been developed. The reaction exhibits broad substrate scope and provides efficient access to cyclohexene derivatives with good to excellent yields. A reasonable mechanism involving a metal-free thermal reversible process is proposed.
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Affiliation(s)
- Wen-Lei Xu
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, Department of Chemistry & Materials Science , Northwest University , Xi'an 710127 , P.R. China
| | - Heng Zhang
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, Department of Chemistry & Materials Science , Northwest University , Xi'an 710127 , P.R. China
| | - Yu-Long Hu
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, Department of Chemistry & Materials Science , Northwest University , Xi'an 710127 , P.R. China
| | - Hui Yang
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, Department of Chemistry & Materials Science , Northwest University , Xi'an 710127 , P.R. China
| | - Jie Chen
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, Department of Chemistry & Materials Science , Northwest University , Xi'an 710127 , P.R. China
| | - Ling Zhou
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, Department of Chemistry & Materials Science , Northwest University , Xi'an 710127 , P.R. China
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Zhang Q, Lv J, Li S, Luo S. Carbocation Lewis Acid Catalyzed Diels–Alder Reactions of Anthracene Derivatives. Org Lett 2018; 20:2269-2272. [DOI: 10.1021/acs.orglett.8b00619] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Qichao Zhang
- Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jian Lv
- Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Sujia Li
- Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Sanzhong Luo
- Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
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Girish YR, Pandit S, Pandit S, De M. Graphene Oxide as a Carbocatalyst for a Diels-Alder Reaction in an Aqueous Medium. Chem Asian J 2017; 12:2393-2398. [DOI: 10.1002/asia.201701072] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 08/14/2017] [Indexed: 12/26/2022]
Affiliation(s)
- Yarabhally R. Girish
- Department of Organic Chemistry; Indian Institute of Science; Bangalore 560012 Karnataka India
| | - Subrata Pandit
- Department of Organic Chemistry; Indian Institute of Science; Bangalore 560012 Karnataka India
| | - Subhendu Pandit
- Department of Organic Chemistry; Indian Institute of Science; Bangalore 560012 Karnataka India
| | - Mrinmoy De
- Department of Organic Chemistry; Indian Institute of Science; Bangalore 560012 Karnataka India
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Raju S, Annamalai P, Chen PL, Liu YH, Chuang SC. Iptycenes with an acridinone motif developed through [4+2] cycloaddition of tethered naphthalene and iminoquinone via a radical reaction. Chem Commun (Camb) 2017; 53:6247-6250. [DOI: 10.1039/c7cc03030d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
A new class of iptycenes was developed by combining 2-(naphthalen-1-yl)anilines and p-benzoquinones through copper(ii)-mediated radical cyclisation.
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Affiliation(s)
- Selvam Raju
- Department of Applied Chemistry
- National Chiao Tung University
- Hsinchu
- Taiwan 30010
| | | | - Pei-Ling Chen
- Department of Chemistry
- National Tsing Hua University
- Hsinchu
- Taiwan 30013
| | - Yi-Hung Liu
- Instrumentation Center
- National Taiwan University
- Taipei
- Taiwan 30010
| | - Shih-Ching Chuang
- Department of Applied Chemistry
- National Chiao Tung University
- Hsinchu
- Taiwan 30010
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