1
|
Patil VB, Raghu Ramudu G, Chegondi R. Cascade Oxypalladation/1,3-Palladium Shift to Access Cyclopentene-Fused Isocoumarins. Org Lett 2024; 26:6353-6358. [PMID: 39041835 DOI: 10.1021/acs.orglett.4c01997] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/24/2024]
Abstract
Fused isocoumarins are frequently found in several natural products and pharmaceuticals. Herein, a cascade annulation of 2-alkynylbenzoate-tethered cyclic 1,3-diones via sequential trans-oxypalladation, carbonyl insertion, 1,3-Pd shift, and β-hydride elimination is reported. This method provides efficient access to highly diastereoselective tetracyclic cyclopentene-fused isocoumarins containing two contiguous quaternary stereocenters. A plausible reaction mechanism is proposed on the basis of mechanistic studies, including deuterium labeling experiments. Studies toward enantioselective synthesis using a chiral Bpy ligand gave encouraging initial results.
Collapse
Affiliation(s)
- Vaibhav B Patil
- Department of Organic Synthesis & Process Chemistry, CSIR-Indian Institute of Chemical Technology (CSIR-IICT), Hyderabad 500007, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - G Raghu Ramudu
- Department of Organic Synthesis & Process Chemistry, CSIR-Indian Institute of Chemical Technology (CSIR-IICT), Hyderabad 500007, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Rambabu Chegondi
- Department of Organic Synthesis & Process Chemistry, CSIR-Indian Institute of Chemical Technology (CSIR-IICT), Hyderabad 500007, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| |
Collapse
|
2
|
Shoji T, Sasahara N, Hamasaki A, Mori S, Okujima T, Sekiguchi R, Ito S. Synthesis, Structural, and Optical Properties of Azuleno[1,2- c]pyran-1-ones: Bro̷nsted Acid-Mediated Cyclization of 2-Azulenylalkynes. J Org Chem 2023. [PMID: 37906944 DOI: 10.1021/acs.joc.3c01742] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
Pyrones and their aromatic ring-fused derivatives have gained significant attention due to their diverse biological activities and potential as foundational frameworks for advanced materials. In this paper, we describe a proficient approach for the preparation of azuleno[1,2-c]pyran-1-ones, which are difficult to produce by using conventional methods. The synthesis was achieved through Bro̷nsted acid-mediated cyclization of 2-azulenylalkynes. The structural and optical properties of azuleno[1,2-c]pyran-1-ones were characterized by single-crystal X-ray analysis, NMR, UV/vis, and fluorescence spectroscopies. Under acidic conditions, these compounds displayed notable spectral alterations and emission, distinct from their spectra in neutral medium. These results suggest that azuleno[1,2-c]pyran-1-ones hold great potential for applications in organic electronic materials and fluorescent pH sensors.
Collapse
Affiliation(s)
- Taku Shoji
- Department of Chemical Biology and Applied Chemistry, College of Engineering, Nihon University, Koriyama 963-8642, Japan
| | - Nichika Sasahara
- Graduate School of Science and Technology, Shinshu University, Matsumoto 390-8621, Japan
| | - Atom Hamasaki
- Graduate School of Science and Technology, Shinshu University, Matsumoto 390-8621, Japan
| | - Shigeki Mori
- Advanced Research Support Center, Ehime University, Matsuyama 790-8577, Japan
| | - Tetsuo Okujima
- Graduate School of Science and Engineering, Ehime University, Matsuyama 790-8577, Japan
| | - Ryuta Sekiguchi
- Graduate School of Science and Technology, Hirosaki University, Hirosaki 036-8561, Japan
| | - Shunji Ito
- Graduate School of Science and Technology, Hirosaki University, Hirosaki 036-8561, Japan
| |
Collapse
|
3
|
Rawat M, Rawat DS. Mesoporous Copper-Magnesium Oxide Hybrid Nanocatalyzed Synthesis of 3-Substituted Isocoumarins from 2-Iodobenzoic Acid and Terminal Alkyne under Green Conditions. ACS OMEGA 2023; 8:16263-16272. [PMID: 37179619 PMCID: PMC10173437 DOI: 10.1021/acsomega.3c00710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 04/12/2023] [Indexed: 05/15/2023]
Abstract
A 3-substituted isocoumarin scaffold has captivated extensive interest in synthetic and medicinal chemistry due to its presence in various natural products with diverse biological activities. Herein, we report a mesoporous CuO@MgO nanocomposite that was prepared via the sugar-blowing induced confined method with an E-factor of 12.2 and its catalytic potential in the facile synthesis of 3-substituted isocoumarin from 2-iodobenzoic acids and terminal alkynes. Powder X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, energy-dispersive X-ray analysis, X-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller techniques were utilized for the characterization of the as-prepared nanocomposite. A broad substrate scope, mild reaction conditions, excellent yield in short reaction time, no usage of additives, and better green chemistry metrices such as a low E-factor (0.71), high reaction mass efficiency (58.28%), low process mass efficiency (1.71), and high turnover number (629) are the various advantages of the present synthetic route. The nanocatalyst was recycled and reused up to five runs without significant loss in its catalytic activity and a very low leaching of copper (3.20 ppm) and magnesium ions (0.72 ppm). Powder X-ray diffraction and high-resolution transmission electron microscopy techniques confirmed the structural integrity of the recycled CuO@MgO nanocomposite.
Collapse
|
4
|
Efficient Synthesis of 1 H-Benzo[4,5]imidazo[1,2- c][1,3]oxazin-1-one Derivatives Using Ag 2CO 3/TFA-Catalyzed 6- endo-dig Cyclization: Reaction Scope and Mechanistic Study. Molecules 2023; 28:molecules28052403. [PMID: 36903655 PMCID: PMC10005794 DOI: 10.3390/molecules28052403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 02/27/2023] [Accepted: 02/28/2023] [Indexed: 03/09/2023] Open
Abstract
A small library of 1H-benzo[4,5]imidazo[1,2-c][1,3]oxazin-1-one derivatives was prepared in good to excellent yields, involving a Ag2CO3/TFA-catalyzed intramolecular oxacyclization of N-Boc-2-alkynylbenzimidazole substrates. In all experiments, the 6-endo-dig cyclization was exclusively achieved since the possible 5-exo-dig heterocycle was not observed, indicating the high regioselectivity of this process. The scope and limitations of the silver catalyzed 6-endo-dig cyclization of N-Boc-2-alkynylbenzimidazoles as substrates, bearing various substituents, were investigated. While ZnCl2 has shown limits for alkynes with an aromatic substituent, Ag2CO3/TFA demonstrated its effectiveness and compatibility regardless of the nature of the starting alkyne (aliphatic, aromatic or heteroaromatic), providing a practical regioselective access to structurally diverse 1H-benzo[4,5]imidazo[1,2-c][1,3]oxazin-1-ones in good yields. Moreover, the rationalization of oxacyclization selectivity in favor of 6-endo-dig over 5-exo-dig was explained by a complementary computational study.
Collapse
|
5
|
Ruggeri D, Motti E, Della Ca' N, Maestri G. Diastereoselective synthesis of tetrahydropyranes via Ag(I)-initiated dimerization of cinnamyl ethers. Org Biomol Chem 2022; 20:9287-9291. [PMID: 36385199 DOI: 10.1039/d2ob01876d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We present herein the first synthesis of tetrahydropyranes promoted by a silver salt. Cinnamyl ethers undergo a formal dimerization affording the target heterocycle via sequential C-O bond cleavage/C-H bond functionalization. The cascade allows one to assemble three new bonds and to establish up to four stereocenters. The reaction likely proceeds through a cationic manifold that forms the target in a diastereoselective fashion.
Collapse
Affiliation(s)
- Davide Ruggeri
- Università di Parma, Dipartimento di Scienze Chimiche, della Vita e della Sostenibilità Ambientale, Parco Area delle Scienze 17/A, 43124 Parma, Italy.
| | - Elena Motti
- Università di Parma, Dipartimento di Scienze Chimiche, della Vita e della Sostenibilità Ambientale, Parco Area delle Scienze 17/A, 43124 Parma, Italy. .,CIRCC (Interuniversity Consortium on Chemical Reactivity and Catalysis), via Celso Ulpiani 27, 70126 Bari, Italy
| | - Nicola Della Ca'
- Università di Parma, Dipartimento di Scienze Chimiche, della Vita e della Sostenibilità Ambientale, Parco Area delle Scienze 17/A, 43124 Parma, Italy. .,CIRCC (Interuniversity Consortium on Chemical Reactivity and Catalysis), via Celso Ulpiani 27, 70126 Bari, Italy
| | - Giovanni Maestri
- Università di Parma, Dipartimento di Scienze Chimiche, della Vita e della Sostenibilità Ambientale, Parco Area delle Scienze 17/A, 43124 Parma, Italy. .,CIRCC (Interuniversity Consortium on Chemical Reactivity and Catalysis), via Celso Ulpiani 27, 70126 Bari, Italy
| |
Collapse
|
6
|
Copper-Free Halodediazoniation of Arenediazonium Tetrafluoroborates in Deep Eutectic Solvents-like Mixtures. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27061909. [PMID: 35335275 PMCID: PMC8950527 DOI: 10.3390/molecules27061909] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 03/09/2022] [Accepted: 03/11/2022] [Indexed: 02/01/2023]
Abstract
Deep Eutectic Solvent (DES)-like mixtures, based on glycerol and different halide organic and inorganic salts, are successfully exploited as new media in copper-free halodediazoniation of arenediazonium salts. The reactions are carried out in absence of metal-based catalysts, at room temperature and in a short time. Pure target products are obtained without the need for chromatographic separation. The solvents are fully characterized, and a computational study is presented aiming to understand the reaction mechanism.
Collapse
|
7
|
Mankad Y, Thorat SS, Das P, Rama Krishna G, Kontham R, Reddy DS. Ready Access to Benzannulated [5,5]-Oxaspirolactones Using Au(III)-Catalyzed Cascade Cyclizations. J Org Chem 2022; 87:3025-3041. [PMID: 35188770 DOI: 10.1021/acs.joc.1c02843] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
This work showcases an unprecedented Au(III)-catalyzed cascade cyclization of 2-(4-hydroxyalkynyl)benzoates to access benzannulated [5,5]-oxaspirolactones related to biologically active natural products. This reaction proceeds through an initial 5-endo-dig mode of hydroalkoxylation of the alkynol segment to give the oxocarbenium species (via cyclic enol-ether) followed by the addition of carboxylate onto the oxocarbenium that delivers the oxaspirolactone scaffold. While testing this method's scope, we found that the steric and electronic environment of the hydroxyl group could alter the reaction pathway that delivers isochromenone through a competitive 6-endo-dig mode of attack of the carboxylate onto the tethered alkyne.
Collapse
Affiliation(s)
- Yash Mankad
- Natural Products and Medicinal Chemistry Division, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu-180001, India.,Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune-411008, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
| | - Sagar S Thorat
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune-411008, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
| | - Pronay Das
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune-411008, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
| | - Gamidi Rama Krishna
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune-411008, India.,Center for Materials Characterization, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune-411008, India
| | - Ravindar Kontham
- Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune-411008, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
| | - D Srinivasa Reddy
- Natural Products and Medicinal Chemistry Division, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu-180001, India.,Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune-411008, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
| |
Collapse
|
8
|
El Qami A, Jismy B, Akssira M, Jacquemin J, Tikad A, Abarbri M. A Ag 2CO 3/TFA-catalyzed intramolecular annulation approach to imidazo[1,2- c][1,3]oxazin-5-one derivatives. Org Biomol Chem 2022; 20:1518-1531. [PMID: 35112683 DOI: 10.1039/d1ob02352g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A series of 2,7-disubstituted 3-methylimidazo[1,2-c][1,3]oxazin-5-ones were synthesized in good yields via Ag2CO3/TFA-mediated intramolecular annulation of N-Boc-2-alkynyl-4-bromo(alkynyl)-5-methylimidazoles. This methodology was carried out in the presence of a catalytic amount of silver carbonate and trifluoroacetic acid in dichloroethane at 60 °C. In all experiments, only the six-membered ring product was obtained since the possible five-membered compound was not observed, proving the high regioselectivity of this approach. A complementary computational study was performed in order to rationalize the mechanism of 6-endo-dig heterocycle formation. In addition, 2-bromo-3-methyl-7-phenylimidazo[1,2-c][1,3]oxazin-5-one was used as a building block to synthesize a small library of new 2-substituted imidazo[1,2-c][1,3]oxazin-5-one derivatives through the Suzuki, Sonogashira and Heck cross coupling reactions.
Collapse
Affiliation(s)
- Abdelkarim El Qami
- Laboratoire de Physico-Chimie des Matériaux et des Electrolytes pour l'Energie (PCM2E), EA 6299, Université de Tours, Faculté des Sciences et Techniques, Avenue Monge Faculté des Sciences, Parc de Grandmont, 37200 Tours, France. .,Laboratoire de Chimie Physique et de Chimie Bioorganique, URAC 22. Université Hassan II de Casablanca, Faculté des Sciences et Techniques de Mohammedia, B.P. 146, 28800 Mohammedia, Morocco
| | - Badr Jismy
- Laboratoire de Physico-Chimie des Matériaux et des Electrolytes pour l'Energie (PCM2E), EA 6299, Université de Tours, Faculté des Sciences et Techniques, Avenue Monge Faculté des Sciences, Parc de Grandmont, 37200 Tours, France.
| | - Mohamed Akssira
- Laboratoire de Chimie Physique et de Chimie Bioorganique, URAC 22. Université Hassan II de Casablanca, Faculté des Sciences et Techniques de Mohammedia, B.P. 146, 28800 Mohammedia, Morocco
| | - Johan Jacquemin
- Laboratoire de Physico-Chimie des Matériaux et des Electrolytes pour l'Energie (PCM2E), EA 6299, Université de Tours, Faculté des Sciences et Techniques, Avenue Monge Faculté des Sciences, Parc de Grandmont, 37200 Tours, France.
| | - Abdellatif Tikad
- Laboratoire de Chimie Moléculaire et Substances Naturelles. Université Moulay Ismail, Faculté des Sciences, B.P. 11201, Zitoune, Meknès, Morocco
| | - Mohamed Abarbri
- Laboratoire de Physico-Chimie des Matériaux et des Electrolytes pour l'Energie (PCM2E), EA 6299, Université de Tours, Faculté des Sciences et Techniques, Avenue Monge Faculté des Sciences, Parc de Grandmont, 37200 Tours, France.
| |
Collapse
|
9
|
Design, synthesis and biological evaluation of new thiazole scaffolds as potential TRPM8 antagonists. Bioorg Med Chem Lett 2021; 52:128392. [PMID: 34606996 DOI: 10.1016/j.bmcl.2021.128392] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 09/24/2021] [Accepted: 09/27/2021] [Indexed: 11/21/2022]
Abstract
The preliminary results on the development of a viable methodology for the further functionalization of 4-hydroxythiazole derivatives to afford target TRPM8 antagonists are reported. The combined Sonogashira coupling/annulation reactions of the ethyl 2-(3-fluorophenyl)-4-tifluoromethylsulfonyloxy-1,3-thiazole-5-carboxylate have been applied to the synthesis of analogues of the selective blocker of TRPM8 DFL23448. Among all the synthetised derivatives, the most promising compound resulted to be active as TRPM8 blocker (IC50 = 4.06 µM), showing an excellent metabolic stability and no cytotoxic effects. Finally, in silico characterisation of the derivatives showed no violation of the drug-likeness rules.
Collapse
|
10
|
Goulart HA, Neto JSS, Barcellos AM, Silva KB, de Moraes MC, Jacob RG, Lenardão EJ, Barcellos T, Perin G. Synthesis of 4-Selanyl- and 4-Tellanyl-1 H-isochromen-1-ones Promoted by Diorganyl Dichalcogenides and Oxone. J Org Chem 2021; 86:14016-14027. [PMID: 33750133 DOI: 10.1021/acs.joc.1c00271] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
A new method was developed for the synthesis of 4-chalcogenyl-1H-isochromen-1-ones through the 6-endo-dig electrophilic cyclization of 2-alkynylaryl esters and diorganyl dichalcogenides under ultrasound irradiation. The reactions were performed under mild conditions, using Oxone as a green oxidant to promote the cleavage of the chalcogen-chalcogen bond in diorganyl diselenides and ditellurides to generate electrophilic species in situ. A total of 25 compounds were selectively obtained after 30-70 min, in good to excellent yields (74-95%). This procedure was extended to prepare 5H-selenopheno[3,2-c]isochromen-5-ones. Additionally, for the first time, the 4-chalcogenyl-1H-isochromen-1-ones were used as substrates in the thionation reaction, using Lawesson's reagent and microwave irradiation under solvent-free conditions, obtaining the thio derivatives in yields of up to 99% in only 15 min.
Collapse
Affiliation(s)
- Helen A Goulart
- Laboratório de Síntese Orgânica Limpa - LASOL, CCQFA, Universidade Federal de Pelotas - UFPel, P.O. Box 354 - 96010-900 Pelotas, RS. Brazil
| | - José S S Neto
- Laboratório de Síntese Orgânica Limpa - LASOL, CCQFA, Universidade Federal de Pelotas - UFPel, P.O. Box 354 - 96010-900 Pelotas, RS. Brazil
| | - Angelita M Barcellos
- Laboratório de Síntese Orgânica Limpa - LASOL, CCQFA, Universidade Federal de Pelotas - UFPel, P.O. Box 354 - 96010-900 Pelotas, RS. Brazil
| | - Krigor B Silva
- Laboratório de Síntese Orgânica Limpa - LASOL, CCQFA, Universidade Federal de Pelotas - UFPel, P.O. Box 354 - 96010-900 Pelotas, RS. Brazil
| | - Maiara C de Moraes
- Laboratory of Biotechnology of Natural and Synthetic Products, Universidade de Caxias do Sul, 95070-560 Caxias do Sul, RS, Brazil
| | - Raquel G Jacob
- Laboratório de Síntese Orgânica Limpa - LASOL, CCQFA, Universidade Federal de Pelotas - UFPel, P.O. Box 354 - 96010-900 Pelotas, RS. Brazil
| | - Eder J Lenardão
- Laboratório de Síntese Orgânica Limpa - LASOL, CCQFA, Universidade Federal de Pelotas - UFPel, P.O. Box 354 - 96010-900 Pelotas, RS. Brazil
| | - Thiago Barcellos
- Laboratory of Biotechnology of Natural and Synthetic Products, Universidade de Caxias do Sul, 95070-560 Caxias do Sul, RS, Brazil
| | - Gelson Perin
- Laboratório de Síntese Orgânica Limpa - LASOL, CCQFA, Universidade Federal de Pelotas - UFPel, P.O. Box 354 - 96010-900 Pelotas, RS. Brazil
| |
Collapse
|
11
|
Synthesis of C2-Symmetrical Bis-(β-Enamino-Pyran-2,4-dione) Derivative Linked via 1,6-Hexylene Spacer: X-ray Crystal Structures, Hishfeld Studies and DFT Calculations of Mono- and Bis-(Pyran-2,4-diones) Derivatives. Symmetry (Basel) 2021. [DOI: 10.3390/sym13091646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The synthesis of C2-symmetrical bis(β-enamino-pyran-2,4-dione) derivative 3 connected via 1,6-hexylene linker was reported for the first time. X-ray structures and Hirshfeld studies of the new bis- β-enamino-pyran-2,4-dione derivative 3 along with two structurally related pyran-2,4-dione derivatives 2a,b were discussed. A comparative analysis of the different intermolecular contacts affecting the crystal stability was presented. Generally, the H…H, O…H, and H…C interactions are common in all compounds and are considered the most abundant contacts. In addition, DFT calculations were used to compute the electronic properties as well as the 1H and 13C NMR spectra of the studied systems. All compounds (except 3) are polar where 2a (3.540 Debye) has a higher dipole moment than 2b (2.110 Debye). The NMR chemical shifts were calculated and excellent correlations between the calculated and experimental data were obtained (R2 = 0.93–0.94).
Collapse
|
12
|
Wu H, Wang YC, Shatskiy A, Li QY, Liu JQ, Kärkäs MD, Wang XS. Modular synthesis of 3-substituted isocoumarins via silver-catalyzed aerobic oxidation/ 6-endo heterocyclization of ortho-alkynylbenzaldehydes. Org Biomol Chem 2021; 19:6657-6664. [PMID: 34271583 DOI: 10.1039/d1ob01065d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
A method involving silver-catalyzed aerobic oxidation/6-endo heterocyclization of ortho-alkynylbenzaldehydes to yield 3-substituted isocoumarins is described. The developed protocol allows convenient access to a range of synthetically useful 3-substituted isocoumarins and related fused heterocyclolactones in good to high yields, using silver tetrafluoroborate as the catalyst, and atmospheric oxygen as the terminal oxidant and the source of endocyclic oxygen. Mechanistic studies suggest the involvement of a free-radical pathway.
Collapse
Affiliation(s)
- Hao Wu
- School of Chemistry and Materials Science, Jiangsu Key Laboratory of Green Synthesis for Functional Materials, Jiangsu Normal University, Xuzhou, Jiangsu 221116, China.
| | - Yi-Chun Wang
- School of Chemistry and Materials Science, Jiangsu Key Laboratory of Green Synthesis for Functional Materials, Jiangsu Normal University, Xuzhou, Jiangsu 221116, China.
| | - Andrey Shatskiy
- Department of Chemistry, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
| | - Qiu-Yan Li
- School of Chemistry and Materials Science, Jiangsu Key Laboratory of Green Synthesis for Functional Materials, Jiangsu Normal University, Xuzhou, Jiangsu 221116, China.
| | - Jian-Quan Liu
- School of Chemistry and Materials Science, Jiangsu Key Laboratory of Green Synthesis for Functional Materials, Jiangsu Normal University, Xuzhou, Jiangsu 221116, China. and Department of Chemistry, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
| | - Markus D Kärkäs
- Department of Chemistry, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
| | - Xiang-Shan Wang
- School of Chemistry and Materials Science, Jiangsu Key Laboratory of Green Synthesis for Functional Materials, Jiangsu Normal University, Xuzhou, Jiangsu 221116, China.
| |
Collapse
|
13
|
Intramolecular Hydrogen Bond, Hirshfeld Analysis, AIM; DFT Studies of Pyran-2,4-dione Derivatives. CRYSTALS 2021. [DOI: 10.3390/cryst11080896] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Intra and intermolecular interactions found in the developed crystals of the synthesized py-ron-2,4-dione derivatives play crucial rules in the molecular conformations and crystal stabili-ties, respectively. In this regard, Hirshfeld calculations were used to quantitatively analyze the different intermolecular interactions in the crystal structures of some functionalized py-ran-2,4-dione derivatives. The X-ray structure of pyran-2,4-dione derivative namely (3E,3′E)-3,3′-((ethane-1,2-diylbis(azanediyl))bis(phenylmethanylylidene))bis(6-phenyl-2H-pyran-2,4(3H)-dione) was determined. It crystallized in the monoclinic crystal system and C2/c space group with unit cell parameters: a = 14.0869(4) Å, b = 20.9041(5) Å, c = 10.1444(2) Å and β = 99.687(2)°. Generally, the H…H, H…C, O…H and C…C contacts are the most important interactions in the molecular packing of the studied pyran-2,4-diones. The molecular structure of these compounds is stabilized by intramolecular O…H hydrogen bond. The nature and strength of the O…H hy-drogen bonds were analyzed using atoms in molecules calculations. In all compounds, the O…H hydrogen bond belongs to closed-shell interactions where the interaction energies are higher at the optimized geometry than the X-ray one due to the shortening in the A…H distance as a con-sequence of the geometry optimization. These compounds have polar characters with different charged regions which explored using molecular electrostatic potential map. Their natural charges, reactivity descriptors and NMR chemical shifts were computed, discussed and compared.
Collapse
|
14
|
Kole PB, Aggarwal H, Narra S, Vernekar A, Singh FV. Metal-free synthesis and single crystal X-ray analysis of 4-aryl-6-hydroxy-2Η-pyran-2-cyanomethylenes. J Mol Struct 2021. [DOI: 10.1016/j.molstruc.2021.129913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
15
|
Yoon JA, Lim C, Han YT. Preliminary Study on Novel Expedient Synthesis of 5-Azaisocoumarins by Transition Metal-Catalyzed Cycloisomerization. Front Chem 2020; 8:772. [PMID: 33102431 PMCID: PMC7500256 DOI: 10.3389/fchem.2020.00772] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 07/24/2020] [Indexed: 11/13/2022] Open
Abstract
A preliminary study to develop a novel synthetic method for 3-aryl-5-azaisocoumarins was performed herein. The cycloisomerization of N-pyranonyl propargylamines in the AgOTf-catalyzed system efficiently afforded the desired 3-aryl-5-azaisocoumarins in a highly regioselective manner. This unprecedented method is expected as an expedient alternative synthetic route to 5-azaisocoumarins because the regioselectivity problem is circumvented, and it is easier to introduce substituents on the pyridine ring compared to previously reported intramolecular lactonization approaches.
Collapse
Affiliation(s)
- Jeong A Yoon
- College of Pharmacy, Dankook University, Cheonan-si, South Korea
| | - Changjin Lim
- School of Pharmacy, Jeonbuk National University, Jeonju-si, South Korea
| | - Young Taek Han
- College of Pharmacy, Dankook University, Cheonan-si, South Korea
| |
Collapse
|
16
|
Le Q, Dillon CC, Lichtenstein DA, Pisor JW, Closser KD, Muchalski H. Gold(I)-NHC-catalysed synthesis of benzofurans via migratory cyclization of 2-alkynylaryl ethers. Org Biomol Chem 2020; 18:8186-8191. [PMID: 33026395 DOI: 10.1039/d0ob01538e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Homogeneous cationic gold(i) catalysis emerged as a preferred avenue for the activation of alkenes and alkynes towards reactions with weak nucleophiles, especially in cyclization reactions. Here we report an intramolecular carboalkoxylation reaction of electron-rich benzyl ethers of 2-ethynylaryl phenols catalysed by a digold(i)-NHC complex. The reaction proceeds efficiently with low catalyst loading and the resulting 2,3-disubstituted benzofurans form in moderate to good yields. Based on the results of a cross-over experiment, spectroscopic data, and DFT calculations, we propose a mechanism that accounts for the observed chemo- and regioselectivity.
Collapse
Affiliation(s)
- Quang Le
- California State University Fresno, 2555 E San Ramon Ave M/S SB70, Fresno, CA 93740, USA.
| | - Christopher C Dillon
- California State University Fresno, 2555 E San Ramon Ave M/S SB70, Fresno, CA 93740, USA.
| | - Dana A Lichtenstein
- California State University Fresno, 2555 E San Ramon Ave M/S SB70, Fresno, CA 93740, USA.
| | - Jeremy W Pisor
- California State University Fresno, 2555 E San Ramon Ave M/S SB70, Fresno, CA 93740, USA.
| | - Kristina D Closser
- California State University Fresno, 2555 E San Ramon Ave M/S SB70, Fresno, CA 93740, USA.
| | - Hubert Muchalski
- California State University Fresno, 2555 E San Ramon Ave M/S SB70, Fresno, CA 93740, USA.
| |
Collapse
|
17
|
Neetha M, Aneeja T, Afsina CMA, Anilkumar G. An Overview of Ag‐catalyzed Synthesis of Six‐membered Heterocycles. ChemCatChem 2020. [DOI: 10.1002/cctc.202000719] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Mohan Neetha
- School of Chemical Sciences Mahatma Gandhi University Priyadarsini Hills P O Kottayam 686560 Kerala India
| | - Thaipparambil Aneeja
- School of Chemical Sciences Mahatma Gandhi University Priyadarsini Hills P O Kottayam 686560 Kerala India
| | - C. M. A. Afsina
- School of Chemical Sciences Mahatma Gandhi University Priyadarsini Hills P O Kottayam 686560 Kerala India
| | - Gopinathan Anilkumar
- School of Chemical Sciences Mahatma Gandhi University Priyadarsini Hills P O Kottayam 686560 Kerala India
- Institute for Integrated Programmes and Research in Basic Sciences (IIRBS) Mahatma Gandhi University Priyadarsini Hills P O Kottayam, 686 560 Kerala India
| |
Collapse
|
18
|
Karuppasamy M, Vachan BS, Jandial T, Babiola Annes S, Bhuvanesh N, Uma Maheswari C, Sridharan V. Palladium(II)‐Catalyzed Direct Access to Indeno[1,2‐
c
]isochromen‐5(11
H
)‐Ones via Intramolecular Oxypalladation‐Initiated Cascade Process. Adv Synth Catal 2020. [DOI: 10.1002/adsc.202000456] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Muthu Karuppasamy
- Department of Chemistry, School of Chemical and BiotechnologySASTRA Deemed University Thanjavur 613401, Tamil Nadu India
| | - B. S. Vachan
- Department of Chemistry, School of Chemical and BiotechnologySASTRA Deemed University Thanjavur 613401, Tamil Nadu India
| | - Tanvi Jandial
- Department of Chemistry and Chemical SciencesCentral University of Jammu, Rahya-Suchani (Bagla), District-Samba Jammu 181143, J&K India
| | - Sesuraj Babiola Annes
- Department of Chemistry, School of Chemical and BiotechnologySASTRA Deemed University Thanjavur 613401, Tamil Nadu India
| | - Nattamai Bhuvanesh
- Department of ChemistryTexas A & M University, College Station Texas 77843 United States
| | - C. Uma Maheswari
- Department of Chemistry, School of Chemical and BiotechnologySASTRA Deemed University Thanjavur 613401, Tamil Nadu India
| | - Vellaisamy Sridharan
- Department of Chemistry, School of Chemical and BiotechnologySASTRA Deemed University Thanjavur 613401, Tamil Nadu India
- Department of Chemistry and Chemical SciencesCentral University of Jammu, Rahya-Suchani (Bagla), District-Samba Jammu 181143, J&K India
| |
Collapse
|
19
|
Gandhi S, Baire B. Fe(III)‐Catalyzed, Cyclizative Coupling between 2‐Alkynylbenzoates and Carbinols: Rapid Generation of Polycyclic Isocoumarins and Phthalides and Mechanistic Study. Adv Synth Catal 2020. [DOI: 10.1002/adsc.202000313] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Soniya Gandhi
- Department of ChemistryInstitute of Technology Madras Chennai 600036
| | - Beeraiah Baire
- Department of ChemistryInstitute of Technology Madras Chennai 600036
| |
Collapse
|
20
|
An X, Zhang B, Li X, Du T, Ai Z, Zhang C, Xu J, Sun F, Zhang Y, Du Y. Construction of 4-(Methylthio)isochromenones Skeleton through Regioselective Intramolecular Cyclization of 2-Alkynylbenzoate Mediated by DMSO/[D6
]DMSO and SOCl2. European J Org Chem 2020. [DOI: 10.1002/ejoc.201901723] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Xuechan An
- School of Pharmaceutical Science and Technology; Tianjin University; 300072 Tianjin China
| | - Beibei Zhang
- School of Pharmaceutical Science and Technology; Tianjin University; 300072 Tianjin China
| | - Xiaoxian Li
- School of Pharmaceutical Science and Technology; Tianjin University; 300072 Tianjin China
| | - Tianshu Du
- School of Pharmaceutical Science and Technology; Tianjin University; 300072 Tianjin China
| | - Zhenkang Ai
- School of Pharmaceutical Science and Technology; Tianjin University; 300072 Tianjin China
| | - Chenglin Zhang
- School of Pharmaceutical Science and Technology; Tianjin University; 300072 Tianjin China
| | - Jun Xu
- School of Pharmaceutical Science and Technology; Tianjin University; 300072 Tianjin China
| | - Fengxia Sun
- College of Chemical and Pharmaceutical Engineering; Hebei University of Science and Technology; Hebei Research Center of Pharmaceutical and Chemical Engineering; 050018 Shijiazhuang China
| | - Yilin Zhang
- C. Eugene Bennett Department of Chemistry; West Virginia University; 26506-6045 Morgantown West Virginia United States
| | - Yunfei Du
- School of Pharmaceutical Science and Technology; Tianjin University; 300072 Tianjin China
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin); 300072 Tianjin China
| |
Collapse
|
21
|
Zhang X, Wan X, Cong Y, Zhen X, Li Q, Zhang-Negrerie D, Du Y, Zhao K. Lactonization of 2-Alkynylbenzoates for the Assembly of Isochromenones Mediated by BF 3·Et 2O. J Org Chem 2019; 84:10402-10411. [PMID: 31328911 DOI: 10.1021/acs.joc.9b01601] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
A general and efficient lactonization method of readily available 2-alkynylbenzoates affording biologically important isochromenones has been realized via a solely BF3·Et2O-mediated 6-endo-dig cyclization process under mild conditions. An alternative mechanistic pathway in which BF3·Et2O activates the carbonyl of the ester moiety, rather than the alkyne triple bond, was postulated on the basis of control experiment results. Gram-scale reaction and further application for the assembly of more complex molecules demonstrated the practicability of the protocol.
Collapse
Affiliation(s)
- Xiang Zhang
- Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, School of Pharmaceutical Science and Technology , Tianjin University , Tianjin 300072 , China
| | - Xintong Wan
- Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, School of Pharmaceutical Science and Technology , Tianjin University , Tianjin 300072 , China
| | - Ying Cong
- Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, School of Pharmaceutical Science and Technology , Tianjin University , Tianjin 300072 , China
| | - Xiaohua Zhen
- Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, School of Pharmaceutical Science and Technology , Tianjin University , Tianjin 300072 , China
| | - Qiao Li
- Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, School of Pharmaceutical Science and Technology , Tianjin University , Tianjin 300072 , China
| | - Daisy Zhang-Negrerie
- Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, School of Pharmaceutical Science and Technology , Tianjin University , Tianjin 300072 , China
| | - Yunfei Du
- Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, School of Pharmaceutical Science and Technology , Tianjin University , Tianjin 300072 , China.,Collaborative Innovation Center of Chemical Science and Engineering (Tianjin) , Tianjin 300072 , China
| | - Kang Zhao
- Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, School of Pharmaceutical Science and Technology , Tianjin University , Tianjin 300072 , China
| |
Collapse
|
22
|
Wang YH, Qiu G, Zhou H, Xie W, Liu JB. Regioselective cyclization of 2-alkynylbenzoic acid in water for the synthesis of isocoumarin. Tetrahedron 2019. [DOI: 10.1016/j.tet.2019.06.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
|
23
|
Yuan J, Zeng F, Mai W, Yang L, Xiao Y, Mao P, Wei D. Fluorination-triggered tandem cyclization of styrene-type carboxylic acids to access 3-aryl isocoumarin derivatives under microwave irradiation. Org Biomol Chem 2019; 17:5038-5046. [PMID: 31045201 DOI: 10.1039/c9ob00509a] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A practical and straightforward synthetic route through a fluorination-triggered tandem cyclization of styrene-type carboxylic acids was developed to construct a variety of 4-fluoro-3-aryl-3,4-dihydroisocoumarins and 3-arylisocoumarins under microwave irradiation. This novel protocol features mild reaction conditions and operational simplicity, with good yields.
Collapse
Affiliation(s)
- Jinwei Yuan
- School of Chemistry & Chemical Engineering, Henan University of Technology, Zhengzhou 450001, P. R. China.
| | - Fanlin Zeng
- School of Chemistry & Chemical Engineering, Henan University of Technology, Zhengzhou 450001, P. R. China.
| | - Wenpeng Mai
- School of Material and Chemical Engineering, Henan Institute of Engineering, Zhengzhou 451191, P. R. China
| | - Liangru Yang
- School of Chemistry & Chemical Engineering, Henan University of Technology, Zhengzhou 450001, P. R. China.
| | - Yongmei Xiao
- School of Chemistry & Chemical Engineering, Henan University of Technology, Zhengzhou 450001, P. R. China.
| | - Pu Mao
- School of Chemistry & Chemical Engineering, Henan University of Technology, Zhengzhou 450001, P. R. China.
| | - Donghui Wei
- College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou 450001, P. R. China
| |
Collapse
|
24
|
Xing L, Zhang Y, Li B, Du Y. Synthesis of 4-Chloroisocoumarins via Intramolecular Halolactonization of o-Alkynylbenzoates: PhICl2-Mediated C–O/C–Cl Bond Formation. Org Lett 2019; 21:1989-1993. [DOI: 10.1021/acs.orglett.9b00047] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Linlin Xing
- Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China
| | - Yong Zhang
- Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China
| | - Bing Li
- Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China
| | - Yunfei Du
- Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072, China
| |
Collapse
|
25
|
Curti F, Tiecco M, Pirovano V, Germani R, Caselli A, Rossi E, Abbiati G. p
-TSA-Based DESs as “Active Green Solvents” for Microwave Enhanced Cyclization of 2-Alkynyl-(hetero)-arylcarboxylates: an Alternative Access to 6-Substituted 3,4-Fused 2-Pyranones. European J Org Chem 2019. [DOI: 10.1002/ejoc.201801884] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Fabiola Curti
- Dipartimento di Scienze Farmaceutiche; Sezione di Chimica Generale e Organica “Alessandro Marchesini”; Università degli Studi di Milano; Via Venezian 21 - 20133 Milano - Italy
| | - Matteo Tiecco
- Dipartimento di Farmacia Università di Chieti-Pescara “G. D'Annunzio”; Via dei Vestini 31 - 66100 Chieti - Italy
| | - Valentina Pirovano
- Dipartimento di Scienze Farmaceutiche; Sezione di Chimica Generale e Organica “Alessandro Marchesini”; Università degli Studi di Milano; Via Venezian 21 - 20133 Milano - Italy
| | - Raimondo Germani
- Dipartimento di Chimica; Università di Perugia; Biologia e Biotecnologie 06123 Perugia - Italy
| | - Alessandro Caselli
- Dipartimento di Chimica; Università degli Studi di Milano; Via Golgi 19 - 20133 Milano - Italy
| | - Elisabetta Rossi
- Dipartimento di Scienze Farmaceutiche; Sezione di Chimica Generale e Organica “Alessandro Marchesini”; Università degli Studi di Milano; Via Venezian 21 - 20133 Milano - Italy
| | - Giorgio Abbiati
- Dipartimento di Scienze Farmaceutiche; Sezione di Chimica Generale e Organica “Alessandro Marchesini”; Università degli Studi di Milano; Via Venezian 21 - 20133 Milano - Italy
| |
Collapse
|
26
|
Dubovtsev AY, Dar'in DV, Krasavin M, Kukushkin VY. Gold-Catalyzed Oxidation of Internal Alkynes into Benzils and its Application for One-Pot Synthesis of Five-, Six-, and Seven-Membered Azaheterocycles. European J Org Chem 2019. [DOI: 10.1002/ejoc.201900108] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Alexey Yu. Dubovtsev
- Saint Petersburg State University; Universitetskaya Nab. 7/9 199034 Saint Petersburg Russian Federation
| | - Dmitry V. Dar'in
- Saint Petersburg State University; Universitetskaya Nab. 7/9 199034 Saint Petersburg Russian Federation
| | - Mikhail Krasavin
- Saint Petersburg State University; Universitetskaya Nab. 7/9 199034 Saint Petersburg Russian Federation
| | - Vadim Yu. Kukushkin
- Saint Petersburg State University; Universitetskaya Nab. 7/9 199034 Saint Petersburg Russian Federation
| |
Collapse
|
27
|
Dillon CC, Keophimphone B, Sanchez M, Kaur P, Muchalski H. Synthesis of 2-substituted benzo[b]thiophenes via gold(i)-NHC-catalyzed cyclization of 2-alkynyl thioanisoles. Org Biomol Chem 2018; 16:9279-9284. [PMID: 30484460 DOI: 10.1039/c8ob02196a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Benzo[b]thiophene heterocycles are important components of many important small molecule pharmaceuticals and drug candidates as well as organic semiconducting materials. Many methods have been developed for the construction of a benzo[b]thiophene core via cyclization reaction of alkynes. Although few catalytic reactions were disclosed, most methods rely on stoichiometric activation of alkynes. Here we report an efficient method for the synthesis of 2-substituted benzo[b]thiophenes from 2-alkynyl thioanisoles catalyzed by a gold(i)-IPr hydroxide that is applicable to a wide range of substrates with diverse electronic and steric properties. Additionally, we demonstrate experimentally that the acid additive and its conjugate base are essential to catalyst turnover.
Collapse
Affiliation(s)
- Christopher C Dillon
- California State University Fresno, 2555 E San Ramon Ave M/S SB70, Fresno, CA 93740, USA.
| | | | | | | | | |
Collapse
|