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Agafonova AV, Golubev AA, Smetanin IA, Khlebnikov AF, Spiridonova DV, Novikov MS. Divergent Synthesis of Pyrazolo[1,5- a]pyridines and Imidazo[1,5- a]pyridines via Reagent-Controlled Cleavage of the C-N or C-C Azirine Bond in 2-Pyridylazirines. Org Lett 2023; 25:7165-7169. [PMID: 37738046 DOI: 10.1021/acs.orglett.3c02696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/23/2023]
Abstract
The three-membered ring in 2-(2-pyridyl)azirine-2-carboxylic esters and thioesters can undergo selective cleavage of either the N-C2 bond under copper(II) catalysis or the C-C bond under the action of HCl to provide isomeric azirine ring expansion products of pyrazolo[1,5-a]pyridine or imidazo[1,5-a]pyridine series, respectively. Mild catalytic reaction conditions for the formation of pyrazolopyridines make it possible to obtain them directly from 4-bromoisoxazoles by a one-pot, three-stage procedure without isolating the intermediate 2-bromoazirines and 2-(2-pyridyl)azirines.
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Affiliation(s)
- Anastasiya V Agafonova
- Institute of Chemistry, St. Petersburg State University, 7/9 Universitetskaya nab., St. Petersburg 199034, Russia
| | - Artem A Golubev
- Institute of Chemistry, St. Petersburg State University, 7/9 Universitetskaya nab., St. Petersburg 199034, Russia
| | - Ilia A Smetanin
- Institute of Chemistry, St. Petersburg State University, 7/9 Universitetskaya nab., St. Petersburg 199034, Russia
| | - Alexander F Khlebnikov
- Institute of Chemistry, St. Petersburg State University, 7/9 Universitetskaya nab., St. Petersburg 199034, Russia
| | - Dar'ya V Spiridonova
- Institute of Chemistry, St. Petersburg State University, 7/9 Universitetskaya nab., St. Petersburg 199034, Russia
| | - Mikhail S Novikov
- Institute of Chemistry, St. Petersburg State University, 7/9 Universitetskaya nab., St. Petersburg 199034, Russia
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Wu WQ, Qin HL. Synthesis of Pyrazolo[1,5- a]pyridinyl, Pyrazolo[1,5- a]quinolinyl, and Pyrazolo[5,1- a]isoquinolinyl Sulfonyl Fluorides via a [3 + 2] Annulation. J Org Chem 2023. [PMID: 36797220 DOI: 10.1021/acs.joc.2c02242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
A [3 + 2] cycloaddition reaction of N-aminopyridines, N-aminoquinolines, and N-aminoisoquinolines with 1-bromoethene-1-sulfonyl fluoride (BESF) was performed to obtain optimum yields of various useful pyrazolo[1,5-a]pyridinyl, pyrazolo[1,5-a]quinolinyl, and pyrazolo[5,1-a]isoquinolinyl sulfonyl fluorides (43-90% yield). The transformation process showed broad substrate specificity, mild reaction conditions, and operational simplicity. Therefore, the reaction has great applicable value in the field of medicinal chemistry and other disciplines.
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Affiliation(s)
- Wen-Qian Wu
- School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, 205 Luoshi Road, Wuhan, 430070, P. R. China
| | - Hua-Li Qin
- School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, 205 Luoshi Road, Wuhan, 430070, P. R. China
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Wang Z, Li X, Qiu J, Li W, Li H, Weng Z, Li H. Modular Access to 2-(Trifluoromethyl)pyrazolo[1,5- a]pyridines and Their Benzo Analogues through a Copper(I)-Catalyzed Radical Annulation. Org Lett 2022; 24:6292-6297. [PMID: 36005387 DOI: 10.1021/acs.orglett.2c02500] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A mechanistically distinctive copper-catalyzed radical annulation to valuable 2-(trifluoromethyl)pyrazolo[1,5-a]pyridines and their benzo analogues has been described for the first time. Notably, the newly developed complementary process allows the synthesis of 4- or 6-substituted target molecular entities as a single product, which was previously challenging to access by existing methods. The utility of this process is further demonstrated by the facile construction of four different ring systems, a gram-scale synthesis, and the late-stage functionalization of bioactive molecules.
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Affiliation(s)
- Zhenhui Wang
- State Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources, School of Chemistry and Pharmaceutical Sciences, Guangxi Normal University, Guilin 541004, China
| | - Xiaofeng Li
- State Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources, School of Chemistry and Pharmaceutical Sciences, Guangxi Normal University, Guilin 541004, China
| | - Jie Qiu
- State Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources, School of Chemistry and Pharmaceutical Sciences, Guangxi Normal University, Guilin 541004, China
| | - Wei Li
- State Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources, School of Chemistry and Pharmaceutical Sciences, Guangxi Normal University, Guilin 541004, China
| | - Hengyuan Li
- State Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources, School of Chemistry and Pharmaceutical Sciences, Guangxi Normal University, Guilin 541004, China
| | - Zhiqiang Weng
- Fujian Engineering Research Center of New Chinese Lacquer Material, Ocean College, Minjiang University, Fuzhou 350108, China
| | - Huaifeng Li
- State Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources, School of Chemistry and Pharmaceutical Sciences, Guangxi Normal University, Guilin 541004, China
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Hsiao PY, Chang R, Sue ACH, Chu JH, Liao GW, Lee YH, Huang JY. Synthesis and Mechanistic Investigation of Bipyrazolo[1,5- a]pyridines via Palladium-Catalyzed Cross-Dehydrogenative Coupling of Pyrazolo[1,5- a]pyridines. J Org Chem 2022; 87:9851-9863. [PMID: 35844185 DOI: 10.1021/acs.joc.2c00895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The synthesis of a range of 3,3'-bipyrazolo[1,5-a]pyridine derivatives via direct cross-dehydrogenative coupling of pyrazolo[1,5-a]pyridine precursors is herein presented. This simple and efficient methodology involving palladium(II)-catalyzed C-H bond activation showed good functional group tolerance and product yield (up to 94%). Through the mechanistic insights gained from both kinetic isotope effect experimental studies and density functional theory calculations, a plausible reaction mechanism was outlined. Furthermore, subsequent derivatizations of the resulting 7,7'-diaryl-3,3'-bipyrazolo[1,5-a]pyridines, executed by performing palladium-mediated ortho C-H bond activation followed by hypervalent iodine-induced chlorination, rendered this series of compounds more extended π-conjugation and twisted conformations. Our study on these bipyrazolo[1,5-a]pyridine-based luminogens provides new opportunities for tailor-made organic luminescent materials.
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Affiliation(s)
- Pu-Yen Hsiao
- Department of Applied Science, National Taitung University, Taitung 95092, Taiwan, R.O.C
| | - Rong Chang
- College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Andrew C-H Sue
- College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Jean-Ho Chu
- Department of Applied Science, National Taitung University, Taitung 95092, Taiwan, R.O.C
| | - Guan-Wei Liao
- Department of Applied Science, National Taitung University, Taitung 95092, Taiwan, R.O.C
| | - Yi-Hsin Lee
- Department of Applied Science, National Taitung University, Taitung 95092, Taiwan, R.O.C
| | - Jui-Yang Huang
- Department of Applied Science, National Taitung University, Taitung 95092, Taiwan, R.O.C
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5
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Wang A, Liu YZ, Shen Z, Qiao Z, Ma X. Regioselective Synthesis of Pyrazolo[1,5- a]pyridine via TEMPO-Mediated [3 + 2] Annulation-Aromatization of N-Aminopyridines and α,β-Unsaturated Compounds. Org Lett 2022; 24:1454-1459. [PMID: 35166547 DOI: 10.1021/acs.orglett.2c00035] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A TEMPO-mediated [3 + 2] annulation-aromatization protocol for the preparation of pyrazolo[1,5-a]pyridines from N-aminopyridines and α,β-unsaturated compounds was developed. The procedure offered multisubstituted pyrazolo[1,5-a]pyridines in good to excellent yield with high and predictable regioselectivity. The modification of marketed drugs including Loratadine, Abiraterone, and Metochalcone, and a one-pot three-step gram scale synthesis of key intermediate for the preparation of Selpercatinib were demonstrated. Mechanism studies show that TEMPO serves both as a Lewis acid and as an oxidant.
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Affiliation(s)
- Amu Wang
- Natural Products Research Centre, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, People's Republic of China.,University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Ya-Zhou Liu
- Natural Products Research Centre, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, People's Republic of China
| | - Zhongke Shen
- Natural Products Research Centre, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, People's Republic of China.,University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Zeen Qiao
- Natural Products Research Centre, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, People's Republic of China
| | - Xiaofeng Ma
- Natural Products Research Centre, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, People's Republic of China
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