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Xu X, Li RP, Zhang Z, Gong X, Zheng Y, Tang S. Regioselective Synthesis of Multisubstituted 2,3-Dihydrooxazoles by 1,3-Dithiane Umpolung. Org Lett 2024; 26:6825-6829. [PMID: 39110706 DOI: 10.1021/acs.orglett.4c02176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/17/2024]
Abstract
Herein, we report a novel strategy for the regioselective synthesis of aromatic and heteroaromatic 2,3-dihydrooxazoles from 2-alkynyl-1,3-dithianes and nitrones. This method exploits the 1,3-dithiane umpolung, nucleophilic cycloaddition, and rearrangement processes to achieve the rapid assembly of dihydrooxazole molecules. The regioselective method is extremely mild, achieving complete conversion within one min under air at 25 °C with high efficiency.
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Affiliation(s)
- Xiangrong Xu
- School of Pharmacy, Lanzhou University, Lanzhou 730000, P. R. China
| | - Rui-Peng Li
- School of Pharmacy, Lanzhou University, Lanzhou 730000, P. R. China
| | - Zhuzhu Zhang
- School of Pharmacy, Lanzhou University, Lanzhou 730000, P. R. China
| | - Xiaomeng Gong
- School of Pharmacy, Lanzhou University, Lanzhou 730000, P. R. China
| | - Yi Zheng
- School of Pharmacy, Lanzhou University, Lanzhou 730000, P. R. China
| | - Shouchu Tang
- School of Pharmacy, Lanzhou University, Lanzhou 730000, P. R. China
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Yang T, Huang C, Jia J, Wu F, Ni F. A Facile Synthesis of 2-Oxazolines via Dehydrative Cyclization Promoted by Triflic Acid. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27249042. [PMID: 36558175 PMCID: PMC9781752 DOI: 10.3390/molecules27249042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Revised: 12/10/2022] [Accepted: 12/15/2022] [Indexed: 12/23/2022]
Abstract
2-oxazolines are common moieties in numerous natural products, pharmaceuticals, and functional copolymers. Current methods for synthesizing 2-oxazolines mainly rely on stoichiometric dehydration agents or catalytic dehydration promoted by specific catalysts. These conditions either generate stoichiometric amounts of waste or require forcing azeotropic reflux conditions. As such, a practical and robust method that promotes dehydrative cyclization while generating no byproducts would be attractive to oxazoline production. Herein, we report a triflic acid (TfOH)-promoted dehydrative cyclization of N-(2-hydroxyethyl)amides for synthesizing 2-oxazolines. This reaction tolerates various functional groups and generates water as the only byproduct. This method affords oxazoline with inversion of α-hydroxyl stereochemistry, suggesting that alcohol is activated as a leaving group under these conditions. Furthermore, the one-pot synthesis protocol of 2-oxazolines directly from carboxylic acids and amino alcohols is also provided.
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Affiliation(s)
- Tao Yang
- Institute of Drug Discovery Technology, Ningbo University, Ningbo 315211, China
- Qian Xuesen Collaborative Research Center of Astrochemistry and Space Life Sciences, Ningbo University, Ningbo 315211, China
| | - Chengjie Huang
- Institute of Drug Discovery Technology, Ningbo University, Ningbo 315211, China
- Qian Xuesen Collaborative Research Center of Astrochemistry and Space Life Sciences, Ningbo University, Ningbo 315211, China
| | - Jingyang Jia
- Institute of Drug Discovery Technology, Ningbo University, Ningbo 315211, China
- Qian Xuesen Collaborative Research Center of Astrochemistry and Space Life Sciences, Ningbo University, Ningbo 315211, China
| | - Fan Wu
- Institute of Drug Discovery Technology, Ningbo University, Ningbo 315211, China
- Qian Xuesen Collaborative Research Center of Astrochemistry and Space Life Sciences, Ningbo University, Ningbo 315211, China
- Correspondence: (F.W.); (F.N.)
| | - Feng Ni
- Institute of Drug Discovery Technology, Ningbo University, Ningbo 315211, China
- Qian Xuesen Collaborative Research Center of Astrochemistry and Space Life Sciences, Ningbo University, Ningbo 315211, China
- Correspondence: (F.W.); (F.N.)
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Taily IM, Saha D, Banerjee P. Aza-Oxyallyl Cation Driven 3-Amido Oxetane Rearrangement to 2-Oxazolines: Access to Oxazoline Amide Ethers. J Org Chem 2022; 87:2155-2166. [PMID: 35129349 DOI: 10.1021/acs.joc.1c03108] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Herein, we report a highly facile and unprecedented activation of 3-amido oxetanes to synthesize 2-oxazoline amide ethers using a transient electrophilic aza-oxyallyl cation as an activating as well as an alkylating agent under mild reaction conditions. The aza-oxyallyl cation driven intramolecular rearrangement of 3-amido oxetanes to 2-oxazolines is the hallmark of this transformation and is a new addition to the reactivity profile of aza-oxyallyl cations.
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Affiliation(s)
- Irshad Maajid Taily
- Department of Chemistry, Indian Institute of Technology Ropar, Rupnagar, Punjab 140001, India
| | - Debarshi Saha
- Department of Chemistry, Indian Institute of Technology Ropar, Rupnagar, Punjab 140001, India
| | - Prabal Banerjee
- Department of Chemistry, Indian Institute of Technology Ropar, Rupnagar, Punjab 140001, India
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Soleymani Movahed F, Foo SW, Mori S, Ogawa S, Saito S. Phosphorus-Based Organocatalysis for the Dehydrative Cyclization of N-(2-Hydroxyethyl)amides into 2-Oxazolines. J Org Chem 2021; 87:243-257. [PMID: 34882422 DOI: 10.1021/acs.joc.1c02318] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A metal-free, biomimetic catalytic protocol for the cyclization of N-(2-hydroxyethyl)amides to the corresponding 2-oxazolines (4,5-dihydrooxazoles), promoted by the 1,3,5,2,4,6-triazatriphosphorine (TAP)-derived organocatalyst tris(o-phenylenedioxy)cyclotriphosphazene (TAP-1) has been developed. This approach requires less precatalyst compared to the reported relevant systems, with respect to the phosphorus atom (the maximum turnover number (TON) ∼ 30), and exhibits a broader substrate scope and higher functional-group tolerance, providing the functionalized 2-oxazolines with retention of the configuration at the C(4) stereogenic center of the 2-oxazolines. Widely accessible β-amino alcohols can be used in this approach, and the cyclization of N-(2-hydroxyethyl)amides provides the desired 2-oxazolines in up to 99% yield. The mechanism of the reaction was studied by monitoring the reaction using spectral and analytical methods, whereby an 18O-labeling experiment furnished valuable insights. The initial step involves a stoichiometric reaction between the substrate and TAP-1, which leads to the in situ generation of the catalyst, a catechol cyclic phosphate, as well as to a pyrocatechol phosphate and two possible active intermediates. The dehydrative cyclization was also successfully conducted on the gram scale.
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Affiliation(s)
| | - Siong Wan Foo
- Graduate School of Science, Nagoya University, Chikusa, Nagoya 464-8602, Japan
| | - Shogo Mori
- Graduate School of Science, Nagoya University, Chikusa, Nagoya 464-8602, Japan
| | - Saeko Ogawa
- Graduate School of Science, Nagoya University, Chikusa, Nagoya 464-8602, Japan
| | - Susumu Saito
- Graduate School of Science, Nagoya University, Chikusa, Nagoya 464-8602, Japan.,Research Center for Materials Science, Nagoya University, Chikusa, Nagoya 464-8602, Japan
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Abazid AH, Hollwedel TN, Nachtsheim BJ. Stereoselective Oxidative Cyclization of N-Allyl Benzamides to Oxaz(ol)ines. Org Lett 2021; 23:5076-5080. [PMID: 34138574 DOI: 10.1021/acs.orglett.1c01607] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
This study presents an enantioselective oxidative cyclization of N-allyl carboxamides via a chiral triazole-substituted iodoarene catalyst. The method allows the synthesis of highly enantioenriched oxazolines and oxazines, with yields of up to 94% and enantioselectivities of up to 98% ee. Quaternary stereocenters can be constructed and, besides N-allyl amides, the corresponding thioamides and imideamides are well tolerated as substrates, giving rise to a plethora of chiral 5-membered N-heterocycles. By applying a multitude of further functionalizations, we finally demonstrate the high value of the observed chiral heterocycles as strategic intermediates for the synthesis of other enantioenriched target structures.
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Affiliation(s)
- Ayham H Abazid
- University of Bremen, Institute of Organic and Analytical Chemistry, Leobener Straße 7, 28359 Bremen, Germany
| | - Tom-Niklas Hollwedel
- University of Bremen, Institute of Organic and Analytical Chemistry, Leobener Straße 7, 28359 Bremen, Germany
| | - Boris J Nachtsheim
- University of Bremen, Institute of Organic and Analytical Chemistry, Leobener Straße 7, 28359 Bremen, Germany
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Kim S, Lee H, Song WY, Kim HJ. Total Syntheses of Fimsbactin A and B and Their Stereoisomers to Probe the Stereoselectivity of the Fimsbactin Uptake Machinery in Acinetobacter baumannii. Org Lett 2020; 22:2806-2810. [PMID: 32212712 DOI: 10.1021/acs.orglett.0c00790] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The stereoselective synthesis of fimsbactin A, a siderophore of the human pathogen Acinetobacter baumannii, was established. Based on this synthetic route, various fimsbactin stereoisomeric analogues were generated and tested for their iron delivery activity for A. baumannii. This investigation revealed that the fimsbactin uptake machinery in this bacterium was indeed highly stereoselective in substrate recognition.
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Affiliation(s)
- Soojeung Kim
- Department of Chemistry, Korea University, Seoul 02841, Republic of Korea
| | - Haeun Lee
- Department of Chemistry, Korea University, Seoul 02841, Republic of Korea
| | - Woon Young Song
- Department of Chemistry, Korea University, Seoul 02841, Republic of Korea
| | - Hak Joong Kim
- Department of Chemistry, Korea University, Seoul 02841, Republic of Korea.,Center for ProteoGenomics Research, Korea University, Seoul 02841, Republic of Korea
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Yamamoto K, Tsuda Y, Kuriyama M, Demizu Y, Onomura O. Copper-Catalyzed Enantioselective Synthesis of Oxazolines from Aminotriols via Asymmetric Desymmetrization. Chem Asian J 2020; 15:840-844. [PMID: 32030893 DOI: 10.1002/asia.201901742] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2019] [Revised: 01/28/2020] [Indexed: 11/06/2022]
Abstract
A copper-catalyzed enantioselective transformation of tris(hydroxymethyl)aminomethane-derived aminotriols was developed to provide multisubstituted oxazolines with a tetrasubstituted carbon center. The present transformation consisted of sequential reactions involving mono-sulfonylation of aminotriols, subsequent intramolecular cyclization to afford prochiral oxazoline diols, and sulfonylative asymmetric desymmetrization of resultant oxazoline diols. In addition, the kinetic resolution process would be involved in the sulfonylative asymmetric desymmetrization step, which would amplify the enantiopurities of the desired products. Various aminotriols were tolerated in the present reaction, affording the desired oxazolines in good to high yields with excellent enantioselectivities. The synthetic utility of the present reaction was demonstrated by the transformation of the optically active oxazoline into a chiral α-tertiary amine motif.
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Affiliation(s)
- Kosuke Yamamoto
- Graduate School of Biomedical Sciences, Nagasaki University 1-14 Bunkyo-machi, Nagasaki, 852-8521, Japan
| | - Yutaro Tsuda
- Graduate School of Biomedical Sciences, Nagasaki University 1-14 Bunkyo-machi, Nagasaki, 852-8521, Japan
| | - Masami Kuriyama
- Graduate School of Biomedical Sciences, Nagasaki University 1-14 Bunkyo-machi, Nagasaki, 852-8521, Japan
| | - Yosuke Demizu
- Graduate School of Biomedical Sciences, Nagasaki University 1-14 Bunkyo-machi, Nagasaki, 852-8521, Japan
| | - Osamu Onomura
- Graduate School of Biomedical Sciences, Nagasaki University 1-14 Bunkyo-machi, Nagasaki, 852-8521, Japan
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Huang H, Yang W, Chen Z, Lai Z, Sun J. A mild catalytic synthesis of 2-oxazolines via oxetane ring-opening: rapid access to a diverse family of natural products. Chem Sci 2019; 10:9586-9590. [PMID: 32055332 PMCID: PMC6993743 DOI: 10.1039/c9sc03843d] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Accepted: 08/24/2019] [Indexed: 12/14/2022] Open
Abstract
A new catalytic protocol for the expedient synthesis of oxazolines from oxetanes is disclosed. This mild process complements the conventional oxazoline synthesis based on non-catalytic cyclization of β-hydroxy or unsaturated amides. It is also a new addition to the reactivity profile of oxetanes leading to heterocycles. In the presence of In(OTf)3, various 3-amido oxetanes underwent smooth intramolecular cyclization to form the corresponding 2-oxazolines, including some valuable oxazoline-based bidentate ligands. This protocol also provides rapid access to various natural products and antibacterial molecules.
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Affiliation(s)
- Hai Huang
- Jiangsu Key Laboratory of Advanced Catalytic Materials & Technology , School of Petrochemical Engineering , Changzhou University , Changzhou 213164 , China .
| | - Wen Yang
- Department of Chemistry and Shenzhen Research Institute , The Hong Kong University of Science and Technology , Clear Water Bay , Kowloon , Hong Kong SAR , China
| | - Zuliang Chen
- Department of Chemistry and Shenzhen Research Institute , The Hong Kong University of Science and Technology , Clear Water Bay , Kowloon , Hong Kong SAR , China
| | - Zengwei Lai
- Department of Chemistry and Shenzhen Research Institute , The Hong Kong University of Science and Technology , Clear Water Bay , Kowloon , Hong Kong SAR , China
| | - Jianwei Sun
- Jiangsu Key Laboratory of Advanced Catalytic Materials & Technology , School of Petrochemical Engineering , Changzhou University , Changzhou 213164 , China .
- Department of Chemistry and Shenzhen Research Institute , The Hong Kong University of Science and Technology , Clear Water Bay , Kowloon , Hong Kong SAR , China
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Lee H, Song WY, Kim M, Lee MW, Kim S, Park YS, Kwak K, Oh MH, Kim HJ. Synthesis and Characterization of Anguibactin To Reveal Its Competence To Function as a Thermally Stable Surrogate Siderophore for a Gram-Negative Pathogen, Acinetobacter baumannii. Org Lett 2018; 20:6476-6479. [DOI: 10.1021/acs.orglett.8b02789] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Haeun Lee
- Department of Chemistry, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
| | - Woon Young Song
- Department of Chemistry, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
| | - Minju Kim
- Department of Chemistry, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science (IBS), Korea University, Seoul 02841, Republic of Korea
| | - Min Wook Lee
- Department of Chemistry, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
| | - Soojeung Kim
- Department of Chemistry, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
| | - Ye Song Park
- Department of Chemistry, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
| | - Kyungwon Kwak
- Department of Chemistry, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
- Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science (IBS), Korea University, Seoul 02841, Republic of Korea
| | - Man Hwan Oh
- Department of Nanobiomedical Science, Dankook University, Cheonan 31116, Republic of Korea
| | - Hak Joong Kim
- Department of Chemistry, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
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A Critical Evaluation of the Quality of Published 13C NMR Data in Natural Product Chemistry. PROGRESS IN THE CHEMISTRY OF ORGANIC NATURAL PRODUCTS 2017; 105:137-215. [PMID: 28194563 DOI: 10.1007/978-3-319-49712-9_3] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Nuclear Magnetic Resonance spectroscopy contributes very efficiently to the structure elucidation process in organic chemistry. Carbon-13 NMR spectroscopy allows direct insight into the skeleton of organic compounds and therefore plays a central role in the structural assignment of natural products. Despite this important contribution, there is no established and well-accepted workflow protocol utilized during the first steps of interpreting spectroscopic data and converting them into structural fragments and then combining them, by considering the given spectroscopic constraints, into a final proposal of structure. The so-called "combinatorial explosion" in the process of structure generation allows in many cases the generation of reasonable alternatives, which are usually ignored during manual interpretation of the measured data leading ultimately to a large number of structural revisions. Furthermore, even when the determined structure is correct, problems may exist such as assignment errors, ignoring chemical shift values, or assigning lines of impurities to the compound under consideration. An extremely large heterogeneity in the presentation of carbon NMR data can be observed, but, as a result of the efficiency and precision of spectrum prediction, the published data can be analyzed in substantial detail.This contribution presents a comprehensive analysis of frequently occurring errors with respect to 13C NMR spectroscopic data and proposes a straightforward protocol to eliminate a high percentage of the most obvious errors. The procedure discussed can be integrated readily into the processes of submission and peer-reviewing of manuscripts.
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