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Wu S, Geng F, Dong J, Liu L, Zhou Y. Metal-Free Oxidative Annulation of Phenols and Amines: A General Synthesis of Benzoxazoles. J Org Chem 2022; 87:9112-9127. [PMID: 35786919 DOI: 10.1021/acs.joc.2c00790] [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
The ubiquity of benzoxazoles in natural products, drugs, and functional materials has stimulated numerous efforts toward their synthesis; however, the developed methods rely on prefunctionalized substrates and lack generality. Under metal-free conditions, a highly general synthesis of benzoxazoles direct from abundant and easily available phenols and amines is developed via a modular phenol functionalization controlled by TEMPO. In the reaction, various phenols and primary amines with a broad range of functional groups are compatible, producing structurally and functionally diverse benzoxazoles (64 examples) without or with trace observation of the byproducts of phenol transformation with amines. The practical synthesis, especially for drug tafamidis, demonstrates decisive advantages in generality, selectivity, efficiency, and atom- and step-economies over traditional methods, even in the cases of low yields. Mechanistically, the radical adducts of TEMPO with ortho-cyclohexa-2,4-dien-1-one radicals rather than the well-recognized cyclohexa-3,5-diene-1,2-diones may serve as intermediates.
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Affiliation(s)
- Shaofeng Wu
- Advanced Catalytic Engineering Research Center of the Ministry of Education, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, China
| | - Furong Geng
- Advanced Catalytic Engineering Research Center of the Ministry of Education, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, China
| | - Jianyu Dong
- School of Physics and Chemistry, Hunan First Normal University, Changsha 410205, China
| | - Long Liu
- Advanced Catalytic Engineering Research Center of the Ministry of Education, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, China
| | - Yongbo Zhou
- Advanced Catalytic Engineering Research Center of the Ministry of Education, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, China
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2
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Ding Y, Wang H, Zheng Q, Guo J, Zhang G, Wang J, Wang X, Guo H. Crystal structure of 2,6-di- tert-butyl-4-(4-chlorobenzylidene)cyclohexa-2,5-dien-1-one, C 21H 25ClO. Z KRIST-NEW CRYST ST 2022. [DOI: 10.1515/ncrs-2022-0056] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
C21H25ClO, orthorhombic, Pna21 (no. 33), a = 14.152(2) Å, b = 22.112(3) Å, c = 6.0109(7) Å, V = 1880.9(4) Å3, Z = 4, R
gt
(F) = 0.0586, wR
ref(F
2) = 0.1227, T = 150 K.
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Affiliation(s)
- Yue Ding
- Shijiazhuang Vocational College of Technology and Information , #2 Hongqi Street, Qiaoxi District , Shijiazhuang , 050091 , China
| | - Hongying Wang
- Shijiazhuang Vocational College of Technology and Information , #2 Hongqi Street, Qiaoxi District , Shijiazhuang , 050091 , China
| | - Qin Zheng
- Shijiazhuang Vocational College of Technology and Information , #2 Hongqi Street, Qiaoxi District , Shijiazhuang , 050091 , China
| | - Jiaojie Guo
- Shijiazhuang Vocational College of Technology and Information , #2 Hongqi Street, Qiaoxi District , Shijiazhuang , 050091 , China
| | - Guangbo Zhang
- Shijiazhuang Vocational College of Technology and Information , #2 Hongqi Street, Qiaoxi District , Shijiazhuang , 050091 , China
| | - Jing Wang
- Shijiazhuang Vocational College of Technology and Information , #2 Hongqi Street, Qiaoxi District , Shijiazhuang , 050091 , China
| | - Xiumin Wang
- Shijiazhuang Vocational College of Technology and Information , #2 Hongqi Street, Qiaoxi District , Shijiazhuang , 050091 , China
| | - Haibo Guo
- Shijiazhuang Food and Drug Inspection Center , #16 Fuqiang Street, Yuhua District , Shijiazhuang , 050022 , China
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3
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Wang T, Zhou Y, Xu Y, Cheng GJ. Computational exploration of copper catalyzed vinylogous aerobic oxidation of unsaturated compounds. Sci Rep 2021; 11:1304. [PMID: 33446723 PMCID: PMC7809353 DOI: 10.1038/s41598-020-80188-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 12/09/2020] [Indexed: 11/23/2022] Open
Abstract
Selective oxidation is one of the most important and challenging transformations in both academic research and chemical industry. Recently, a highly selective and efficient way to synthesize biologically active γ-hydroxy-α,β-unsaturated molecules from Cu-catalyzed vinylogous aerobic oxidation of α,β- and β,γ-unsaturated compounds has been developed. However, the detailed reaction mechanism remains elusive. Herein, we report a density functional theory study on this Cu-catalyzed vinylogous aerobic oxidation of γ,γ-disubstituted α,β- and β,γ-unsaturated isomers. Our computational study unveils detailed mechanism for each elementary step, i.e. deprotonation, O2 activation, and reduction. Besides, the origin of regioselectivity, divergent reactivities of substrates as well as reducing agents, and the byproduct generation have also been investigated. Notably, the copper catalyst retains the + 2 oxidation state through the whole catalytic cycle and plays essential roles in multiple steps. These findings would provide hints on mechanistic studies and future development of transition metal-catalyzed aerobic oxidation reactions.
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Affiliation(s)
- Ting Wang
- Warshel Institute for Computational Biology, Shenzhen Key Laboratory of Steroid Drug Development, School of Life and Health Sciences, The Chinese University of Hong Kong (Shenzhen), Shenzhen, 518172, China
| | - Yu Zhou
- Warshel Institute for Computational Biology, Shenzhen Key Laboratory of Steroid Drug Development, School of Life and Health Sciences, The Chinese University of Hong Kong (Shenzhen), Shenzhen, 518172, China
- School of Life Sciences, University of Science and Technology of China, Hefei, 230027, Anhui, China
| | - Yao Xu
- Warshel Institute for Computational Biology, Shenzhen Key Laboratory of Steroid Drug Development, School of Life and Health Sciences, The Chinese University of Hong Kong (Shenzhen), Shenzhen, 518172, China
- School of Life Sciences, University of Science and Technology of China, Hefei, 230027, Anhui, China
| | - Gui-Juan Cheng
- Warshel Institute for Computational Biology, Shenzhen Key Laboratory of Steroid Drug Development, School of Life and Health Sciences, The Chinese University of Hong Kong (Shenzhen), Shenzhen, 518172, China.
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4
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Chandra G, Patel S. Molecular Complexity from Aromatics: Recent Advances in the Chemistry of
para
Quinol and Masked
para
‐Quinone Monoketal. ChemistrySelect 2020. [DOI: 10.1002/slct.202003802] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Girish Chandra
- Department of Chemistry School of Physical and Chemical Sciences Central University of South Bihar SH-7, Gaya-Panchanpur Road Gaya Bihar India 824236
| | - Samridhi Patel
- Department of Chemistry School of Physical and Chemical Sciences Central University of South Bihar SH-7, Gaya-Panchanpur Road Gaya Bihar India 824236
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5
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Li T, Yan D, Cui C, Song X, Chang J. A thermal decarboxylative Cloke–Wilson rearrangement of dispirocyclopropanes derived from para-quinone methides and bromo-Meldrum's acids: an approach to synthesize spirobutyrolactone para-dienones. Org Chem Front 2020. [DOI: 10.1039/d0qo00770f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
An unprecedented approach to synthesize spirobutyrolactone para-dienones from para-quinone methides and bromo-Meldrum's acids has been developed.
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Affiliation(s)
- Tong Li
- College of Chemistry
- Zhengzhou University
- Zhengzhou 450001
- China
| | - Dandan Yan
- Shanghai Gengcai New Material Technology Co. Ltd
- Shanghai 201108
- China
| | - Chaoxing Cui
- College of Chemistry
- Zhengzhou University
- Zhengzhou 450001
- China
| | - Xixi Song
- College of Chemistry
- Zhengzhou University
- Zhengzhou 450001
- China
| | - Junbiao Chang
- College of Chemistry
- Zhengzhou University
- Zhengzhou 450001
- China
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6
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Abstract
The selective oxidation of organic molecules is a fundamentally important component of modern synthetic chemistry. In the past decades, direct oxidative C-H and C-C bond functionalization has proved to be one of the most efficient and straightforward methods to synthesize complex products from simple and readily available starting materials. Among these oxidative processes, the use of molecular oxygen as a green and sustainable oxidant has attracted considerable attention because of its highly atom-economical, abundant, and environmentally friendly characteristics. The development of new protocols using molecular oxygen as an ideal oxidant is highly desirable in oxidation chemistry. More importantly, the oxygenation reaction of simple molecules using molecular oxygen as the oxygen source offers one of the most ideal processes for the construction of O-containing compounds. Aerobic oxidation and oxygenation by enzymes, such as monooxygenase, tyrosinase, and dopamine β-monooxygenase, have been observed in some biological C-H bond hydroxylation processes. Encouraged by these biological transformations, transition-metal- or organocatalyst-catalyzed oxygenation through dioxygen activation has attracted academic and industrial prospects. In this Account, we describe some advances from our group in oxygenation via C-H/C-C bond activation with molecular oxygen as the oxidant and oxygen source for the synthesis of O-containing compounds. Under an atmosphere of O2 (1 atm) or air (1 atm), we have successfully incorporated one or two O atoms from O2 into simple and readily available substrates through C-H, C-C, C═C, and C≡C bond cleavage by transition-metal catalysis, organocatalysis, and photocatalysis. Moreover, we have devised cyclization reactions with molecular oxygen to construct O-heterocycles. Most of these transformations can tolerate a broad range of functional groups. Furthermore, on the basis of isotope labeling experiments, electron paramagnetic resonance spectral analysis, and other mechanistic studies, we have demonstrated that a single electron transfer process via a carbon radical, peroxide radical, or hydroxyl radical is involved in these aerobic oxidation and oxygenation reactions. These protocols provide new approaches for the green synthesis of various α-keto amides, α-keto esters, esters, ketones, aldehydes, formamides, 2-oxoacetamidines, 2-(1H)-pyridones, phenols, tertiary α-hydroxy carbonyls, p-quinols, β-azido alcohols, benzyl alcohols, tryptophols, and oxazoles, which have potential applications in the preparation of natural products, bioactive compounds, and functional materials. In most cases, inexpensive and low-toxicity Cu, Fe, Mn, or NHPI was found to be an efficient catalyst for the transformation. The high efficiency, low cost, high oxygen atom economy, broad substrate scope, and practical operation make the developed oxygenation system very attractive and practical. Moreover, the design of new types of molecular-oxygen- or air-based oxidation and oxygenation reactions can be anticipated.
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Affiliation(s)
- Yu-Feng Liang
- State
Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical
Sciences, Peking University, Xue Yuan Road 38, Beijing 100191, China
| | - Ning Jiao
- State
Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical
Sciences, Peking University, Xue Yuan Road 38, Beijing 100191, China
- State
Key Laboratory of Organometallic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China
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7
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Budzikiewicz H. The ortho-quinol acetates (die ortho-Chinolacetate): 20 years of dedicated research in Vienna and what happened then? MONATSHEFTE FUR CHEMIE 2016. [DOI: 10.1007/s00706-015-1635-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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8
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Liang YF, Wang X, Tang C, Shen T, Liu J, Jiao N. NHPI and palladium cocatalyzed aerobic oxidative acylation of arenes through a radical process. Chem Commun (Camb) 2016; 52:1416-9. [DOI: 10.1039/c5cc08945j] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Molecular oxygen, the most environmentally friendly oxidant, was used as the terminal oxidant for palladium-catalyzed radical oxidative acylation of arenes.
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Affiliation(s)
- Yu-Feng Liang
- State Key Laboratory of Natural and Biomimetic Drugs
- Peking University
- School of Pharmaceutical Sciences
- Peking University
- Beijing 100191
| | - Xiaoyang Wang
- State Key Laboratory of Natural and Biomimetic Drugs
- Peking University
- School of Pharmaceutical Sciences
- Peking University
- Beijing 100191
| | - Conghui Tang
- State Key Laboratory of Natural and Biomimetic Drugs
- Peking University
- School of Pharmaceutical Sciences
- Peking University
- Beijing 100191
| | - Tao Shen
- State Key Laboratory of Natural and Biomimetic Drugs
- Peking University
- School of Pharmaceutical Sciences
- Peking University
- Beijing 100191
| | - Jianzhong Liu
- State Key Laboratory of Natural and Biomimetic Drugs
- Peking University
- School of Pharmaceutical Sciences
- Peking University
- Beijing 100191
| | - Ning Jiao
- State Key Laboratory of Natural and Biomimetic Drugs
- Peking University
- School of Pharmaceutical Sciences
- Peking University
- Beijing 100191
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