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Wang Y, Wang S, Liu J, Song Q. Difluorocarbene Enables Access to 2,2-Difluorohydrobenzofurans and 2-Fluorobenzofurans from ortho-Vinylphenols. Org Lett 2024; 26:3744-3749. [PMID: 38687275 DOI: 10.1021/acs.orglett.4c00779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2024]
Abstract
2-Fluorobenzofurans are the backbone structures of many drug molecules and have many potential therapeutic bioactivities. Despite the potential applications in medicinal chemistry, practical and efficient synthetic methods for the construction of 2-fluorobenzofuran are very limited. Herein, we report an efficient and general method for the construction of 2-fluorobenzofurans. Contrary to the previous functionalizations of the existing backbone of benzofuran, our strategy directly constructs benzofuran scaffolds alongside the incorporation of fluorine atom on C2 position in a formal [4 + 1] cyclization from readily accessible ortho-vinylphenols and difluorocarbene. In our strategy, ClCF2H decomposes into difluorocarbene in the presence of base, which is further captured by the oxygen anion from the hydroxy group in ortho-hydroxychalcones; subsequent intramolecular Michael addition to the α, β-unsaturated system leads to 2,2-difluorohydrobenzofurans, and further fluorine elimination renders 2-fluorobenzofurans by forming one C-O bond and one C-C double bond. Of note, various complex 2,2-difluorohydrobenzofurans and 2-fluorobenzofurans could be readily accessed through our protocol via the late-stage elaborations.
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Affiliation(s)
- Yahao Wang
- Key Laboratory of Molecule Synthesis and Function Discovery, Fujian Province University, College of Chemistry at Fuzhou University, Fuzhou, Fujian 350108, China
| | - Shuai Wang
- Key Laboratory of Molecule Synthesis and Function Discovery, Fujian Province University, College of Chemistry at Fuzhou University, Fuzhou, Fujian 350108, China
| | - Jianbo Liu
- Key Laboratory of Molecule Synthesis and Function Discovery, Fujian Province University, College of Chemistry at Fuzhou University, Fuzhou, Fujian 350108, China
| | - Qiuling Song
- Key Laboratory of Molecule Synthesis and Function Discovery, Fujian Province University, College of Chemistry at Fuzhou University, Fuzhou, Fujian 350108, China
- Institute of Next Generation Matter Transformation, College of Material Sciences Engineering, Huaqiao University, Xiamen, Fujian 361021, China
- State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China
- School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan 453007, China
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He X, Ling J, Fang Z, Zhou L. Synthesis of 2-Fluorobenzofuran by Photocatalytic Defluorinative Coupling and 5 -endo-trig Cyclization. J Org Chem 2023. [PMID: 37126028 DOI: 10.1021/acs.joc.3c00559] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
An alkyl radical-triggered dual C-F bond cleavage of α-CF3-ortho-hydroxystyrenes for the synthesis of 2-fluorobenzofurans was developed. The visible-light-induced defluorinative cross-coupling reactions of α-CF3-ortho-hydroxystyrenes with a variety of carboxylic acids produced gem-difluoroalkenes, which underwent SNV-type 5-endo-trig cyclization to give 2-fluorobenzofurans. Mechanistic studies indicated that the electron transfer between phenoxyl radicals and carboxylates was the major pathway for the generation of alkyl radicals.
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Affiliation(s)
- Xiaoli He
- School of Chemistry, Sun Yat-Sen University, Guangzhou, 510006, China
| | - Jiahao Ling
- School of Chemistry, Sun Yat-Sen University, Guangzhou, 510006, China
| | - Zhixing Fang
- School of Chemistry, Sun Yat-Sen University, Guangzhou, 510006, China
| | - Lei Zhou
- School of Chemistry, Sun Yat-Sen University, Guangzhou, 510006, China
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Ishibashi Y, Fujita T, Ichikawa J. Two-Step Synthesis of 2-Trifluoromethylated and 2-Difluoromethylated Benzoheteroles Starting from HFO-1224yd( Z) and HFO-1233yd( Z). Org Lett 2022; 24:9306-9310. [PMID: 36508571 DOI: 10.1021/acs.orglett.2c03930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
An efficient two-step method for synthesizing 2-(trifluoromethyl)- and 2-(difluoromethyl)benzoheteroles bearing various substituents was developed. Commercially available HFO-1224yd(Z) or HFO-1233yd(Z) underwent the Suzuki-Miyaura coupling with arylboronic acids (acid esters) bearing a nucleophilic moiety at the ortho position to yield the corresponding β-fluoro-β-(trifluoromethyl)- or β-fluoro-β-(difluoromethyl)styrenes, respectively. Treatment of the obtained styrenes with potassium phosphate induced nucleophilic 5-endo-trig cyclization to provide the corresponding 2-trifluoromethylated or 2-difluoromethylated indoles and benzofurans, as well as benzothiophenes.
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Affiliation(s)
- Yuichiro Ishibashi
- Division of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan
| | - Takeshi Fujita
- Division of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan
| | - Junji Ichikawa
- Division of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan
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Fujita T, Fukuda T, Suzuki N, Ichikawa J. Rapid Synthesis of Fused Polycyclic Heteroaromatics via Successive Vinylic/Aromatic C–F Bond Activation. European J Org Chem 2022. [DOI: 10.1002/ejoc.202200600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Takeshi Fujita
- University of Tsukuba: Tsukuba Daigaku Division of Chemistry JAPAN
| | - Takuya Fukuda
- University of Tsukuba: Tsukuba Daigaku Division of Chemistry JAPAN
| | - Naoto Suzuki
- University of Tsukuba: Tsukuba Daigaku Division of Chemistry JAPAN
| | - Junji Ichikawa
- University of Tsukuba Department of Chemistry 1-1-1 Tennodai 305-8571 Tsukuba JAPAN
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Fuchibe K, Yamada A, Hachinohe K, Matsumoto K, Takayama R, Ichikawa J. Synthesis of Difluoroalkenes from Thiocarbonyl Compounds via Difluorothiiranes: Electrophilic Counterpart to Wittig-Type Difluoromethylidenation. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2021. [DOI: 10.1246/bcsj.20210248] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Kohei Fuchibe
- Division of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan
| | - Atsushi Yamada
- Division of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan
| | - Kosei Hachinohe
- Division of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan
| | - Kana Matsumoto
- Division of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan
| | - Ryo Takayama
- Division of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan
| | - Junji Ichikawa
- Division of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan
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Fujita T, Morioka R, Fukuda T, Suzuki N, Ichikawa J. Acid-mediated intermolecular C-F/C-H cross-coupling of 2-fluorobenzofurans with arenes: synthesis of 2-arylbenzofurans. Chem Commun (Camb) 2021; 57:8500-8503. [PMID: 34351333 DOI: 10.1039/d1cc03453g] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Transition-metal-free acid-promoted biaryl construction was achieved via intermolecular C-F/C-H cross-coupling. By treating 2-fluorobenzofurans with arenes in the presence of AlCl3, 2-arylbenzofurans were obtained. This protocol was successfully applied to the short-step orthogonal synthesis of a bioactive 2-arylbenzofuran natural product, which allows independent transformations of C-F and C-Br bonds. Mechanistic studies indicated that α-fluorine-stabilized carbocations, generated via the protonation of 2-fluorobenzofurans, served as key intermediates. The Friedel-Crafts-type C-C bond formation between the α-fluorocarbocations and arenes, followed by hydrogen fluoride elimination, afforded 2-arylbenzofurans.
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Affiliation(s)
- Takeshi Fujita
- Division of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan.
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