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Kumar Yadav A, Yadav D, Kumar V, Ray S, Singh MS. PIDA-promoted metal-free [3 + 2] heteroannulation of β-ketothioamides with 4-hydroxy coumarins: chemo-/regioselective access to furo[3,2- c]chromen-4-ones at room temperature. Org Biomol Chem 2024; 22:4326-4331. [PMID: 38722080 DOI: 10.1039/d4ob00438h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2024]
Abstract
Herein, we report a viable protocol to access furo[3,2-c]chromen-4-ones by engaging easily accessible 4-hydroxy coumarins as a three-atom CCO unit and thioamides as a C2 coupling partner, mediated by phenyliodine(III) diacetate (PIDA) at room temperature in a highly efficient and pot-/step-economical manner. This strategy not only avoids potential toxicity and tiresome workup conditions, but also features operational simplicity, a broad substrate scope, good functional group tolerance, high yields, easy scalability and exclusive selectivity. A mechanistic study has shown that this metal-free reaction is triggered by PIDA via activation of the β-carbon of 4-hydroxy coumarin, followed by a nucleophilic addition/intramolecular cyclization/dethiohydration cascade. High-resolution mass spectra (HRMS) study confirms the key intermediates involved during the course of the reaction, elucidating the reaction pathways, and demonstrates the excellent regio- and chemoselectivity of this approach.
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Affiliation(s)
- Anup Kumar Yadav
- Department of Chemistry, Institute of Science, Banaras Hindu University, Varanasi 221005, India.
| | - Dhananjay Yadav
- Department of Chemistry, Institute of Science, Banaras Hindu University, Varanasi 221005, India.
| | - Vipin Kumar
- Department of Chemistry, Institute of Science, Banaras Hindu University, Varanasi 221005, India.
| | - Subhasish Ray
- Department of Chemistry, Institute of Science, Banaras Hindu University, Varanasi 221005, India.
| | - Maya Shankar Singh
- Department of Chemistry, Institute of Science, Banaras Hindu University, Varanasi 221005, India.
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2
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Zhuang W, Xiao F, Chen Y, Zhang X, Huang Q. Cascade Electrochemical Aerobic Oxygenation of 2-Substituted Indoles and Electrochemical [5 + 3] Annulation with Amidines: Access to Eight-Membered Benzo[1,3,5]triazocin-6(5 H)-ones. J Org Chem 2024; 89:4673-4683. [PMID: 38478890 DOI: 10.1021/acs.joc.3c02931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/06/2024]
Abstract
The cascade electrochemical C3-selective aerobic oxygenation of 2-substituted indoles and electrochemical [5 + 3] annulation with amidines through an undivided cell galvanostatic method employing molecular oxygen and "electricity" as green oxidants was developed. This protocol provides an efficient and direct approach to eight-membered benzo[1,3,5]triazocin-6(5H)-ones. Mechanistic studies suggested that two subsequent electrochemical processes both proceeded through radical pathways.
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Affiliation(s)
- Weihui Zhuang
- Fujian Provincial Key Laboratory of Advanced Materials Oriented Chemical Engineering, College of Chemistry & Materials Science, Fujian Normal University, Fuzhou, Fujian 350007, PR China
| | - Fengyi Xiao
- Fujian Provincial Key Laboratory of Advanced Materials Oriented Chemical Engineering, College of Chemistry & Materials Science, Fujian Normal University, Fuzhou, Fujian 350007, PR China
| | - Yumei Chen
- Fujian Provincial Key Laboratory of Advanced Materials Oriented Chemical Engineering, College of Chemistry & Materials Science, Fujian Normal University, Fuzhou, Fujian 350007, PR China
| | - Xiaofeng Zhang
- Fujian Provincial Key Laboratory of Advanced Materials Oriented Chemical Engineering, College of Chemistry & Materials Science, Fujian Normal University, Fuzhou, Fujian 350007, PR China
| | - Qiufeng Huang
- Fujian Provincial Key Laboratory of Advanced Materials Oriented Chemical Engineering, College of Chemistry & Materials Science, Fujian Normal University, Fuzhou, Fujian 350007, PR China
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3
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Pali P, Singh MS. Radical-Cascade Avenue to Access 1,2-Dithioles Employing Dithioesters and Edman's Reagent. Org Lett 2023; 25:2258-2263. [PMID: 36966396 DOI: 10.1021/acs.orglett.3c00509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/27/2023]
Abstract
An operationally simple and efficient domino etiquette has been developed for the facile construction of 1,2-dithioles employing easily accessible dithioesters as a three-atom CCS synthon and aryl isothiocyanates as a two-atom CS unit in the absence of any catalyst and additive at room temperature under open air. The reaction proceeded efficiently affording the desired 1,2-dithioles in good yields having various functional groups of a diverse electronic and steric nature. This approach avoids possible toxicity and tiresome workup conditions and features easy to handle, cheap, and readily accessible reagents, O2 as a green oxidant, and gram-scale ability. Notably, the final S-S bond formation and cascade ring construction follow a radical pathway, which has been recognized via a radical trapping experiment with BHT during the course of the reaction. Notably, the exocyclic C═N bond at position 3 of 1,2-dithiole possesses Z stereochemistry.
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Affiliation(s)
- Pragya Pali
- Department of Chemistry, Institute of Science, Banaras Hindu University, Varanasi 221005, India
| | - Maya Shankar Singh
- Department of Chemistry, Institute of Science, Banaras Hindu University, Varanasi 221005, India
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4
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Khan S, Ansari MA, Singh MS. Access to Functionalized Thiazolothiadiazoles via the Chemoselective Cascade Heteroannulation of Thioamides with Hypervalent Iodine Reagents. Org Lett 2023; 25:642-646. [PMID: 36656125 DOI: 10.1021/acs.orglett.2c04223] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
We describe herein a chemo- and regioselective cascade annulation between β-ketothioamides and diazo-substituted hypervalent iodine reagents under transition-metal-free and base-free conditions at room temperature. Thus, a divergent construction of fused-heterocyclic scaffold thiazolothiadiazoles has been achieved with the advantages of operational simplicity, scalability, broad substrate compatibility, and mild reaction conditions. This one-pot strategy not only avoids potential toxicity but also broadens the arsenal of synthetic methods to obtain fused N,S-heterocyclic frameworks.
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Affiliation(s)
- Shahnawaz Khan
- Department of Chemistry, Institute of Science, Banaras Hindu University, Varanasi, Uttar Pradesh221005, India
| | - Monish Arbaz Ansari
- Department of Chemistry, Institute of Science, Banaras Hindu University, Varanasi, Uttar Pradesh221005, India
| | - Maya Shankar Singh
- Department of Chemistry, Institute of Science, Banaras Hindu University, Varanasi, Uttar Pradesh221005, India
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Meng X, Guo W, Nan G, Li M. Synthesis of pyrrole disulfides via umpolung of β-ketothioamides. Org Biomol Chem 2022; 20:7609-7612. [PMID: 36156622 DOI: 10.1039/d2ob01506d] [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 Na2CO3-promoted reaction of β-ketothioamides (KTAs) and cyanoacetates was developed for the synthesis of pyrrole disulfides using air as a green oxidant. This protocol features a broad substrate scope and mild reaction conditions. Preliminary mechanistic studies indicate that the reaction involves a tandem unusual umpolung of KTAs, N-cyclization, tautomerization and oxidative coupling process.
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Affiliation(s)
- Xiangrui Meng
- Key Lab of Natural Product Chemistry and Application in Xinjiang, School of Chemistry and Environmental Science, Yili Normal University, Yining 835000, P. R. China.
| | - Weisi Guo
- College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042, P. R. China.
| | - Guangming Nan
- Key Lab of Natural Product Chemistry and Application in Xinjiang, School of Chemistry and Environmental Science, Yili Normal University, Yining 835000, P. R. China.
| | - Ming Li
- Key Lab of Natural Product Chemistry and Application in Xinjiang, School of Chemistry and Environmental Science, Yili Normal University, Yining 835000, P. R. China. .,College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042, P. R. China.
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Zhang Y, Li K, Gao W, Liu X, Yuan H, Tang L, Fan Z. Tandem Synthesis of 1,2,3-Thiadiazoles with 3,4-Dichloroisothiazoles and Hydrazines under External Oxidant- and Sulfur-Free Conditions. Org Lett 2022; 24:6599-6603. [PMID: 36054902 DOI: 10.1021/acs.orglett.2c02595] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
1,2,3-Thiadiazoles are among the most important heterocyclic motifs, with wide applications in natural products and medicinal chemistry. Herein, we disclose a tandem reaction for the synthesis of structurally diverse 1,2,3-thiadiazoles from 3,4-dichloroisothiazol-5-ketones and hydrazines. This method is characterized by mild external oxidant- and sulter-free reaction conditions, a broad substrate scope, and easy purification.
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Affiliation(s)
- Yue Zhang
- State Key Laboratory of Elemento-Organic Chemistry, Research Institute of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, People's Republic of China
| | - Kun Li
- State Key Laboratory of Elemento-Organic Chemistry, Research Institute of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, People's Republic of China
| | - Wei Gao
- State Key Laboratory of Elemento-Organic Chemistry, Research Institute of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, People's Republic of China
| | - Xiaoyu Liu
- State Key Laboratory of Elemento-Organic Chemistry, Research Institute of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, People's Republic of China
| | - Haolin Yuan
- State Key Laboratory of Elemento-Organic Chemistry, Research Institute of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, People's Republic of China
| | - Liangfu Tang
- State Key Laboratory of Elemento-Organic Chemistry, Research Institute of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, People's Republic of China.,Frontiers Science Center for New Organic Matter, College of Chemistry, Nankai University, Tianjin 300071, People's Republic of China
| | - Zhijin Fan
- State Key Laboratory of Elemento-Organic Chemistry, Research Institute of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, People's Republic of China.,Frontiers Science Center for New Organic Matter, College of Chemistry, Nankai University, Tianjin 300071, People's Republic of China
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Pali P, Yadav D, Sahoo SC, Shankar Singh M. Metal-Free One-Pot Annulative Coupling of 2-Hydroxybenzaldehydes with β-Ketothioamides: Access to Diverse 2-Arylimino-2 H-Chromenes. J Org Chem 2022; 87:12342-12351. [PMID: 36037527 DOI: 10.1021/acs.joc.2c01581] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A concise and practical one-pot sustainable approach for expedient synthesis of 2-arylimino-2H-chromenes by two-component cascade [4 + 2] annulative coupling of easily available 2-hydroxybenzaldehydes with β-ketothioamides has been developed in good yields for the first time. Remarkably, metal- and additive-free conditions, use of simple K2CO3 as a mild base, open atmosphere, exclusive regioselectivity, step/atom economy, nonhazardous reagents, and easy purification are added characteristics to the strategy. This annulative protocol will not only provide an efficient method to access diverse chromene scaffolds, but also enrich the research domain of β-ketothioamides.
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Affiliation(s)
- Pragya Pali
- Department of Chemistry, Institute of Science, Banaras Hindu University, Varanasi 221005, India
| | - Dhananjay Yadav
- Department of Chemistry, Institute of Science, Banaras Hindu University, Varanasi 221005, India
| | - Subash C Sahoo
- Department of Chemistry, Panjab University, Chandigarh 160014, India
| | - Maya Shankar Singh
- Department of Chemistry, Institute of Science, Banaras Hindu University, Varanasi 221005, India
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Shukla G, Yadav D, Singh S, Shankar Singh M. Access to Nitrones from Amines via Electrocatalysis at Room Temperature. Adv Synth Catal 2022. [DOI: 10.1002/adsc.202200188] [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)
- Gaurav Shukla
- Department of Chemistry Institute of Science Banaras Hindu University Varanasi 221005 India
| | - Dhananjay Yadav
- Department of Chemistry Institute of Science Banaras Hindu University Varanasi 221005 India
| | - Saurabh Singh
- Department of Chemistry Institute of Science Banaras Hindu University Varanasi 221005 India
| | - Maya Shankar Singh
- Department of Chemistry Institute of Science Banaras Hindu University Varanasi 221005 India
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