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Gao ZX, Wang H, Su AH, Li QY, Liang Z, Zhang YQ, Liu XY, Zhu MZ, Zhang HX, Hou YT, Li X, Sun LR, Li J, Xu ZJ, Lou HX. Asymmetric Synthesis and Biological Evaluation of Platensilin, Platensimycin, Platencin, and Their Analogs via a Bioinspired Skeletal Reconstruction Approach. J Am Chem Soc 2024; 146:18967-18978. [PMID: 38973592 DOI: 10.1021/jacs.4c02256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/09/2024]
Abstract
Platensilin, platensimycin, and platencin are potent inhibitors of β-ketoacyl-acyl carrier protein synthase (FabF) in the bacterial and mammalian fatty acid synthesis system, presenting promising drug leads for both antibacterial and antidiabetic therapies. Herein, a bioinspired skeleton reconstruction approach is reported, which enables the unified synthesis of these three natural FabF inhibitors and their skeletally diverse analogs, all stemming from a common ent-pimarane core. The synthesis features a diastereoselective biocatalytic reduction and an intermolecular Diels-Alder reaction to prepare the common ent-pimarane core. From this intermediate, stereoselective Mn-catalyzed hydrogen atom-transfer hydrogenation and subsequent Cu-catalyzed carbenoid C-H insertion afford platensilin. Furthermore, the intramolecular Diels-Alder reaction succeeded by regioselective ring opening of the newly formed cyclopropane enables the construction of the bicyclo[3.2.1]-octane and bicyclo[2.2.2]-octane ring systems of platensimycin and platencin, respectively. This skeletal reconstruction approach of the ent-pimarane core facilitates the preparation of analogs bearing different polycyclic scaffolds. Among these analogs, the previously unexplored cyclopropyl analog 47 exhibits improved antibacterial activity (MIC80 = 0.0625 μg/mL) against S. aureus compared to platensimycin.
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Affiliation(s)
- Zong-Xu Gao
- Department of Natural Products Chemistry, Key Laboratory of Chemical Biology, School of Pharmaceutical Sciences, Shandong University, No. 44, Wenhuaxi Rd, Jinan 250012, P. R. China
| | - Hongliang Wang
- School of Pharmaceutical Sciences & Institute of Materia Medica, State Key Laboratory of Advanced Drug Delivery System, Shandong First Medical University & Shandong Academy of Medical Sciences, No. 6699, Qingdao Rd, Jinan 250117, P. R. China
| | - Ai-Hong Su
- Department of Natural Products Chemistry, Key Laboratory of Chemical Biology, School of Pharmaceutical Sciences, Shandong University, No. 44, Wenhuaxi Rd, Jinan 250012, P. R. China
| | - Qian-Ying Li
- Department of Natural Products Chemistry, Key Laboratory of Chemical Biology, School of Pharmaceutical Sciences, Shandong University, No. 44, Wenhuaxi Rd, Jinan 250012, P. R. China
| | - Zhen Liang
- Department of Natural Products Chemistry, Key Laboratory of Chemical Biology, School of Pharmaceutical Sciences, Shandong University, No. 44, Wenhuaxi Rd, Jinan 250012, P. R. China
| | - Yue-Qing Zhang
- Department of Natural Products Chemistry, Key Laboratory of Chemical Biology, School of Pharmaceutical Sciences, Shandong University, No. 44, Wenhuaxi Rd, Jinan 250012, P. R. China
| | - Xu-Yuan Liu
- Department of Natural Products Chemistry, Key Laboratory of Chemical Biology, School of Pharmaceutical Sciences, Shandong University, No. 44, Wenhuaxi Rd, Jinan 250012, P. R. China
| | - Ming-Zhu Zhu
- Department of Natural Products Chemistry, Key Laboratory of Chemical Biology, School of Pharmaceutical Sciences, Shandong University, No. 44, Wenhuaxi Rd, Jinan 250012, P. R. China
| | - Hai-Xia Zhang
- Department of Natural Products Chemistry, Key Laboratory of Chemical Biology, School of Pharmaceutical Sciences, Shandong University, No. 44, Wenhuaxi Rd, Jinan 250012, P. R. China
| | - Yue-Tong Hou
- Department of Natural Products Chemistry, Key Laboratory of Chemical Biology, School of Pharmaceutical Sciences, Shandong University, No. 44, Wenhuaxi Rd, Jinan 250012, P. R. China
| | - Xin Li
- School of Pharmaceutical Sciences & Institute of Materia Medica, State Key Laboratory of Advanced Drug Delivery System, Shandong First Medical University & Shandong Academy of Medical Sciences, No. 6699, Qingdao Rd, Jinan 250117, P. R. China
| | - Long-Ru Sun
- Department of Natural Products Chemistry, Key Laboratory of Chemical Biology, School of Pharmaceutical Sciences, Shandong University, No. 44, Wenhuaxi Rd, Jinan 250012, P. R. China
| | - Jian Li
- Frontiers Science Center for Transformative Molecules, School of Chemistry and Chemical Engineering, Zhangjiang Institute for Advanced Study, Shanghai Jiao Tong University, No. 429, Zhangheng Rd, Shanghai 200213, P. R. China
| | - Ze-Jun Xu
- Department of Natural Products Chemistry, Key Laboratory of Chemical Biology, School of Pharmaceutical Sciences, Shandong University, No. 44, Wenhuaxi Rd, Jinan 250012, P. R. China
| | - Hong-Xiang Lou
- Department of Natural Products Chemistry, Key Laboratory of Chemical Biology, School of Pharmaceutical Sciences, Shandong University, No. 44, Wenhuaxi Rd, Jinan 250012, P. R. China
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Ji J, Chen J, Qin S, Li W, Zhao J, Li G, Song H, Liu XY, Qin Y. Total Synthesis of Vilmoraconitine. J Am Chem Soc 2023; 145:3903-3908. [PMID: 36779887 DOI: 10.1021/jacs.3c00318] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
Vilmoraconitine belongs to one of the most complex skeleton types in the C19-diterpenoid alkaloids, which architecturally features an unprecedented heptacyclic core possessing a rigid cyclopropane unit. Here, we report the first total synthesis of vilmoraconitine relying on strategic use of efficient ring-forming reactions. Key steps include an oxidative dearomatization-induced Diels-Alder cycloaddition, a hydrodealkenylative fragmentation/Mannich sequence, and an intramolecular Diels-Alder cycloaddition.
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Affiliation(s)
- Jiujian Ji
- Key Laboratory of Drug-Targeting and Drug Delivery System of the Education Ministry and Sichuan Province, Sichuan Engineering Laboratory for Plant-Sourced Drug and Sichuan Research Center for Drug Precision Industrial Technology, West China School of Pharmacy, Sichuan University, Chengdu, 610041, China
| | - Jiajun Chen
- Key Laboratory of Drug-Targeting and Drug Delivery System of the Education Ministry and Sichuan Province, Sichuan Engineering Laboratory for Plant-Sourced Drug and Sichuan Research Center for Drug Precision Industrial Technology, West China School of Pharmacy, Sichuan University, Chengdu, 610041, China
| | - Sixun Qin
- Key Laboratory of Drug-Targeting and Drug Delivery System of the Education Ministry and Sichuan Province, Sichuan Engineering Laboratory for Plant-Sourced Drug and Sichuan Research Center for Drug Precision Industrial Technology, West China School of Pharmacy, Sichuan University, Chengdu, 610041, China
| | - Wanye Li
- Key Laboratory of Drug-Targeting and Drug Delivery System of the Education Ministry and Sichuan Province, Sichuan Engineering Laboratory for Plant-Sourced Drug and Sichuan Research Center for Drug Precision Industrial Technology, West China School of Pharmacy, Sichuan University, Chengdu, 610041, China
| | - Jun Zhao
- Key Laboratory of Drug-Targeting and Drug Delivery System of the Education Ministry and Sichuan Province, Sichuan Engineering Laboratory for Plant-Sourced Drug and Sichuan Research Center for Drug Precision Industrial Technology, West China School of Pharmacy, Sichuan University, Chengdu, 610041, China
| | - Guozhao Li
- Key Laboratory of Drug-Targeting and Drug Delivery System of the Education Ministry and Sichuan Province, Sichuan Engineering Laboratory for Plant-Sourced Drug and Sichuan Research Center for Drug Precision Industrial Technology, West China School of Pharmacy, Sichuan University, Chengdu, 610041, China
| | - Hao Song
- Key Laboratory of Drug-Targeting and Drug Delivery System of the Education Ministry and Sichuan Province, Sichuan Engineering Laboratory for Plant-Sourced Drug and Sichuan Research Center for Drug Precision Industrial Technology, West China School of Pharmacy, Sichuan University, Chengdu, 610041, China
| | - Xiao-Yu Liu
- Key Laboratory of Drug-Targeting and Drug Delivery System of the Education Ministry and Sichuan Province, Sichuan Engineering Laboratory for Plant-Sourced Drug and Sichuan Research Center for Drug Precision Industrial Technology, West China School of Pharmacy, Sichuan University, Chengdu, 610041, China
| | - Yong Qin
- Key Laboratory of Drug-Targeting and Drug Delivery System of the Education Ministry and Sichuan Province, Sichuan Engineering Laboratory for Plant-Sourced Drug and Sichuan Research Center for Drug Precision Industrial Technology, West China School of Pharmacy, Sichuan University, Chengdu, 610041, China
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Qu C, Long X, Sang Y, Zhang M, Zhao X, Xue XS, Deng J. Biomimetic Total Synthesis of (±)-Carbocyclinone-534 Reveals Its Biosynthetic Pathway. Org Lett 2020; 22:9421-9426. [PMID: 33086787 DOI: 10.1021/acs.orglett.0c02865] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Carbocyclinone-534 is a new antibiotic produced after the metabolism of tapinarof. We identify a biomimetic total synthesis of carbocyclinone-534 in eight steps by taking advantage of an intermolecular Diels-Alder homodimerization/dehydrogenation/intramolecular Diels-Alder cycloaddition cascade. This synthetic sequence provides direct experimental evidence for revealing the biosynthetic pathway of carbocyclinone-534.
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Affiliation(s)
- Chunlei Qu
- State Key Laboratory of Phytochemistry and Plant Resources in West China and Yunnan Key Laboratory of Natural Medicinal Chemistry, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming 100049, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xianwen Long
- State Key Laboratory of Phytochemistry and Plant Resources in West China and Yunnan Key Laboratory of Natural Medicinal Chemistry, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming 100049, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yueqian Sang
- State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Min Zhang
- State Key Laboratory of Phytochemistry and Plant Resources in West China and Yunnan Key Laboratory of Natural Medicinal Chemistry, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming 100049, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiaoli Zhao
- State Key Laboratory of Phytochemistry and Plant Resources in West China and Yunnan Key Laboratory of Natural Medicinal Chemistry, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming 100049, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiao-Song Xue
- State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
| | - Jun Deng
- State Key Laboratory of Phytochemistry and Plant Resources in West China and Yunnan Key Laboratory of Natural Medicinal Chemistry, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming 100049, China
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Wein LA, Wurst K, Angyal P, Weisheit L, Magauer T. Synthesis of (-)-Mitrephorone A via a Bioinspired Late Stage C-H Oxidation of (-)-Mitrephorone B. J Am Chem Soc 2019; 141:19589-19593. [PMID: 31770485 DOI: 10.1021/jacs.9b11646] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We present a bioinspired late-stage C-H oxidation of the ent-trachylobane natural product mitrephorone B to mitrephorone A. The realization of this unprecedented transformation was accomplished by either an iron-catalyzed or electrochemical oxidation and enabled access to the densely substituted oxetane in one step. Formation of mitrephorone C, which is lacking the central oxetane unit but features a keto-function at C2, was not formed under these conditions.
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Affiliation(s)
- Lukas Anton Wein
- Institute of Organic Chemistry and Center for Molecular Biosciences , Leopold-Franzens-University Innsbruck , Innrain 80-82 , 6020 Innsbruck , Austria
| | - Klaus Wurst
- Institute of General, Inorganic and Theoretical Chemistry , Leopold-Franzens-University Innsbruck , Innrain 80-82 , 6020 Innsbruck , Austria
| | - Peter Angyal
- Institute of Organic Chemistry , Research Centre for Natural Sciences , Magyar tudósok körútja 2 , 1117 Budapest , Hungary
| | - Lara Weisheit
- Institute of Organic Chemistry and Center for Molecular Biosciences , Leopold-Franzens-University Innsbruck , Innrain 80-82 , 6020 Innsbruck , Austria
| | - Thomas Magauer
- Institute of Organic Chemistry and Center for Molecular Biosciences , Leopold-Franzens-University Innsbruck , Innrain 80-82 , 6020 Innsbruck , Austria
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6
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Glendening E, Weinhold F. Natural resonance theory of chemical reactivity, with illustrative application to intramolecular Claisen rearrangement. Tetrahedron 2018. [DOI: 10.1016/j.tet.2018.07.054] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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7
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Pham HV, Martin DBC, Vanderwal CD, Houk KN. The Intramolecular Diels-Alder Reaction of Tryptamine-Derived Zincke Aldehydes Is a Stepwise Process. Chem Sci 2012; 2012:1650-1655. [PMID: 22611483 DOI: 10.1039/c2sc01072k] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Computational studies show that the base-mediated intramolecular Diels-Alder of tryptamine-derived Zincke aldehydes, used as a key step in the synthesis of the Strychnos alkaloids norfluorocurarine and strychnine, proceeds via a stepwise pathway. The experimentally determined importance of a potassium counterion in the base is explained by its ability to preorganize the Zincke aldehyde diene in an s-cis conformation suitable to bicyclization. Computation also supports the thermodynamic importance of the generation of a stable enolate in the final reaction step. The thermal cycloreversion reaction of the Diels-Alder products is also found to proceed in a stepwise manner.
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Affiliation(s)
- Hung V Pham
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive, Los Angeles, California 90095-1569
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Rodriguez AM, Prieto P, de la Hoz A, Díaz-Ortiz A. “In silico” mechanistic studies as predictive tools in microwave-assisted organic synthesis. Org Biomol Chem 2011; 9:2371-7. [DOI: 10.1039/c0ob01037e] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Schoenebeck F, Ess DH, Jones GO, Houk KN. Reactivity and Regioselectivity in 1,3-Dipolar Cycloadditions of Azides to Strained Alkynes and Alkenes: A Computational Study. J Am Chem Soc 2009; 131:8121-33. [DOI: 10.1021/ja9003624] [Citation(s) in RCA: 182] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Franziska Schoenebeck
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095
| | - Daniel H. Ess
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095
| | - Gavin O. Jones
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095
| | - K. N. Houk
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095
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Chopin N, Gérard H, Chataigner I, Piettre SR. Benzofurans as Efficient Dienophiles in Normal Electron Demand [4 + 2] Cycloadditions. J Org Chem 2008; 74:1237-46. [DOI: 10.1021/jo802205d] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Nathalie Chopin
- UMR CNRS 6014, IRCOF, Université de Rouen, 1 Rue Tesnières, F-76821 Mont Saint Aignan, France, and Laboratoire de Chimie Théorique, Université Paris VI, 3, rue Galilée, F-94200 Ivry-sur-Seine, France
| | - Hélène Gérard
- UMR CNRS 6014, IRCOF, Université de Rouen, 1 Rue Tesnières, F-76821 Mont Saint Aignan, France, and Laboratoire de Chimie Théorique, Université Paris VI, 3, rue Galilée, F-94200 Ivry-sur-Seine, France
| | - Isabelle Chataigner
- UMR CNRS 6014, IRCOF, Université de Rouen, 1 Rue Tesnières, F-76821 Mont Saint Aignan, France, and Laboratoire de Chimie Théorique, Université Paris VI, 3, rue Galilée, F-94200 Ivry-sur-Seine, France
| | - Serge R. Piettre
- UMR CNRS 6014, IRCOF, Université de Rouen, 1 Rue Tesnières, F-76821 Mont Saint Aignan, France, and Laboratoire de Chimie Théorique, Université Paris VI, 3, rue Galilée, F-94200 Ivry-sur-Seine, France
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Dadwal M, Kesharwani MK, Danayak V, Ganguly B, Mobin SM, Muruganantham R, Namboothiri INN. Synthetic and Theoretical Investigations on the Construction of Oxanorbornenes by a Michael Addition and Intramolecular Diels-Alder Furan Reaction. European J Org Chem 2008. [DOI: 10.1002/ejoc.200800681] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Lahiri S, Yadav S, Banerjee S, Patil MP, Sunoj RB. Face-Selective Diels−Alder Reactions between Unsymmetrical Cyclohexadienes and Symmetric trans-Dienophile: An Experimental and Computational Investigation. J Org Chem 2007; 73:435-44. [DOI: 10.1021/jo701884d] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Saswati Lahiri
- Department of Organic Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India, and Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Somnath Yadav
- Department of Organic Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India, and Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Srirupa Banerjee
- Department of Organic Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India, and Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Mahendra P. Patil
- Department of Organic Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India, and Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Raghavan B. Sunoj
- Department of Organic Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India, and Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
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James PV, Sudeep PK, Suresh CH, Thomas KG. Photophysical and theoretical investigations of oligo(p-phenyleneethynylene)s: effect of alkoxy substitution and alkyne-aryl bond rotations. J Phys Chem A 2007; 110:4329-37. [PMID: 16571035 DOI: 10.1021/jp055184o] [Citation(s) in RCA: 132] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The unique photophysical, conformational, and electronic properties of two model phenyleneethynylene-based rigid rod molecular systems, possessing dialkoxy substitutions, are reported in comparison with an unsubstituted system. Twisting of the phenyl rings along the carbon-carbon triple bond is almost frictionless in these systems giving rise to planar as well as several twisted ground-state conformations, and this results in broad structureless absorption in the spectral region of 250-450 nm. In the case of 1,4-bis(phenylethynyl)benzene, a broad absorption band was observed due to the HOMO-LUMO transition, whereas dialkoxy-substituted compounds possess two well-separated bands. Dialkoxy substitution in the 2,5-position of the phenyl ring in phenyleneethynylenes alters its central arene pi-orbitals through the resonance interaction with oxygen lone pairs resulting in similar orbital features for HOMO and HOMO-1/HOMO-2. Electronic transition from the low-lying HOMO-1/HOMO-2 orbital to LUMO results in the high-energy band, and the red-shifted band originates from the HOMO-LUMO transition. The first excited-state transition energies at different dihedral angles, calculated by the TDDFT method, indicate that the orthogonal conformation has the highest excitation energy with an energy difference of 15 kcal/mol higher than the low-lying planar conformation. The emission of these compounds originates preferentially from the more relaxed planar conformation resulting in well-defined vibronic features. The fluorescence spectral profile and lifetimes were found to be independent of excitation wavelengths, confirming the existence of a single emitting species.
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Affiliation(s)
- P V James
- Photosciences and Photonics, Chemical Sciences Division, Regional Research Laboratory (CSIR), Trivandrum 695 019 India
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Chataigner I, Panel C, Gérard H, Piettre SR. Sulfonyl vs. carbonyl group: which is the more electron-withdrawing? Chem Commun (Camb) 2007:3288-90. [PMID: 17668103 DOI: 10.1039/b705034h] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Unexpectedly high reactivity of nitrogenated aromatics protected as amides or carbamates, when compared to sulfonamides, can be explained by a decrease of the aromaticity due to a greater ability of the carbon-centered groups to achieve delocalisation of the nitrogen lone pair, resulting in stronger global withdrawing effects.
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Affiliation(s)
- Isabelle Chataigner
- Laboratoire des Fonctions Azotées et Oxygénées Complexes, Université de Rouen, UMR CNRS 6014, F-76821, Mont Saint Aignan, France.
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Patil MP, Sunoj RB. Density functional theory and atoms-in-molecule study on the role of two-electron stabilizing interactions in retro Diels–Alder reaction of cycloadducts derived from substituted cyclopentadiene and p-benzoquinone. Org Biomol Chem 2006; 4:3923-30. [PMID: 17047871 DOI: 10.1039/b610972a] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A systematic investigation on the cycloreversion reaction of the cycloadduct formed between substituted cyclopentadiene and p-benzoquinone (1-19) is reported at the B3LYP/6-311+G**//B3LYP/6-31G* level of theory. The computed activation barrier exhibits a fairly high sensitivity to the nature of substituents at the C7-position. Gibbs free energy of activation for 1 and 19 are found to be 20.3 and 30.1 kcal mol(-1), respectively, compared to 7, which is estimated to be 24.7 kcal mol(-1). Quantitative analysis of the electronic effects operating in both the cycloadduct as well as the corresponding transition state for the retro Diels-Alder (rDA) reaction performed using the natural bond orbital (NBO) and atoms in molecule (AIM) methods have identified important two-electron stabilizing interactions. Among four major delocalizations, sigma(C7-X) to sigma*(C1-C5) [and to sigma*(C2-C6)] is identified as the key contributing factor responsible for ground state C1-C5 bond elongation, which in turn is found to be crucial in promoting the rDA reaction. A good correlation between the population of antibonding orbital [sigma*(C1-C5)] of the ground state cycloadduct and Gibbs free energy of activation is observed. The importance of factors that modulate ground state structural features in controlling the energetics of rDA reaction is described.
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Affiliation(s)
- Mahendra P Patil
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
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Lamsabhi AM, Escobar CA, Pérez P. Do substituents make any contribution to the formation of systems where the electronic effects seem to be neutralized? The case of the indigo dye formation. J PHYS ORG CHEM 2005. [DOI: 10.1002/poc.984] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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