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Kumari R, Jha AK, Khan AGH, Easwar S. Mechanistic Investigations on the Interaction of Morita-Baylis-Hillman Ketones with 2-Aminothiophenol. J Org Chem 2024; 89:7263-7269. [PMID: 38684077 DOI: 10.1021/acs.joc.3c02993] [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
The reaction of Morita-Baylis-Hillman ketones with 2-aminothiophenol mediated by Cs2CO3 results in an oxidative cyclization to 2,2-disubstituted dihydro-1,4-benzothiazines, with the structure of the product indicating the occurrence of an aza-Michael addition along the pathway. In contrast, in the absence of a base, the parent compounds interact to produce a thia-Michael adduct instead. A deeper mechanistic study improved our understanding of the apparent contradiction and provided insight into the base-dependent switch in reactivity.
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Affiliation(s)
- Rajkiran Kumari
- Department of Chemistry, School of Chemical Sciences and Pharmacy, Central University of Rajasthan, NH-8, Bandarsindri District, Ajmer, Rajasthan 305817, India
| | - Ajit Kumar Jha
- Department of Chemistry, School of Chemical Sciences and Pharmacy, Central University of Rajasthan, NH-8, Bandarsindri District, Ajmer, Rajasthan 305817, India
| | - Akram Gulam Hussain Khan
- Department of Chemistry, School of Chemical Sciences and Pharmacy, Central University of Rajasthan, NH-8, Bandarsindri District, Ajmer, Rajasthan 305817, India
| | - Srinivasan Easwar
- Department of Chemistry, School of Chemical Sciences and Pharmacy, Central University of Rajasthan, NH-8, Bandarsindri District, Ajmer, Rajasthan 305817, India
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Kumari R, Jha AK, Goyal S, Maan R, Reddy SR, Easwar S. Acyl Transfer-Driven Rauhut-Currier Dimerization of Morita-Baylis-Hillman Ketones. J Org Chem 2023; 88:2023-2033. [PMID: 36753536 DOI: 10.1021/acs.joc.2c02244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
A serendipitous Rauhut-Currier dimerization of 1,1-disubstituted activated olefins derived from Morita-Baylis-Hillman adducts was observed in the presence of DABCO. The reaction is driven by the migration of an acyl group and produces multifunctionalized enol esters in yields greater than 90% in most cases, without necessitating column chromatographic purification. The acyl transfer is thought to proceed via a transition state typical of a Morita-Baylis-Hillman (MBH) reaction, supported by a brief mechanistic study involving computational calculations.
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Affiliation(s)
- Rajkiran Kumari
- Department of Chemistry, School of Chemical Sciences and Pharmacy, Central University of Rajasthan, NH-8, Bandarsindri, Ajmer 305817, Rajasthan, India
| | - Ajit Kumar Jha
- Department of Chemistry, School of Chemical Sciences and Pharmacy, Central University of Rajasthan, NH-8, Bandarsindri, Ajmer 305817, Rajasthan, India
| | - Sophiya Goyal
- Department of Chemistry, School of Chemical Sciences and Pharmacy, Central University of Rajasthan, NH-8, Bandarsindri, Ajmer 305817, Rajasthan, India
| | - Reena Maan
- Department of Chemistry, School of Chemical Sciences and Pharmacy, Central University of Rajasthan, NH-8, Bandarsindri, Ajmer 305817, Rajasthan, India
| | - S Rajagopala Reddy
- Department of Chemistry, School of Chemical Sciences and Pharmacy, Central University of Rajasthan, NH-8, Bandarsindri, Ajmer 305817, Rajasthan, India
| | - Srinivasan Easwar
- Department of Chemistry, School of Chemical Sciences and Pharmacy, Central University of Rajasthan, NH-8, Bandarsindri, Ajmer 305817, Rajasthan, India
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Jha AK, Kumari R, Easwar S. Synthesis of 2,2-Disubstituted Dihydro-1,4-benzothiazines from Morita-Baylis-Hillman Ketones by an Oxidative Cyclization. J Org Chem 2022; 87:5760-5772. [PMID: 35441520 DOI: 10.1021/acs.joc.2c00087] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
An oxidative cyclization ensued upon interaction of Morita-Baylis-Hillman (MBH) ketones with 2-aminothiophenol in the presence of Cs2CO3, resulting in the formation of new 2,2-disubstituted dihydro-1,4-benzothiazines. The reaction features an aza-Michael addition and an oxidative cyclization involving the formation of a carbon-sulfur bond and works well over a wide range of MBH ketones to deliver the dihydrobenzothiazines in good yields in reasonable reaction times under mild conditions.
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Affiliation(s)
- Ajit Kumar Jha
- Department of Chemistry, School of Chemical Sciences and Pharmacy, Central University of Rajasthan, NH-8, Bandarsindri, Ajmer, Rajasthan 305817, India
| | - Rajkiran Kumari
- Department of Chemistry, School of Chemical Sciences and Pharmacy, Central University of Rajasthan, NH-8, Bandarsindri, Ajmer, Rajasthan 305817, India
| | - Srinivasan Easwar
- Department of Chemistry, School of Chemical Sciences and Pharmacy, Central University of Rajasthan, NH-8, Bandarsindri, Ajmer, Rajasthan 305817, India
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Kumar Jha A, Deeksha, Inani H, Easwar S. An isatin Aldol Adduct as a precursor to α,α’-Difunctionalized Methyl Vinyl Ketones. RESULTS IN CHEMISTRY 2022. [DOI: 10.1016/j.rechem.2022.100339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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α-Substituted β-mercapto ketone based synthesis of 3-alkyl-3-[(alkylsulfanyl)methyl]-2-methyl-3H-indoles. Chem Heterocycl Compd (N Y) 2021. [DOI: 10.1007/s10593-021-02940-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Jin J, Li Y, Xiang S, Fan W, Guo S, Huang D. Selectfluor facilitated bridging of indoles to bis(indolyl)methanes using methyl tert-butyl ether as a new methylene precursor. Org Biomol Chem 2021; 19:4076-4081. [PMID: 33978036 DOI: 10.1039/d1ob00120e] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A novel, green and efficient method is developed for the synthesis of methylene bridged bis(indolyl)methanes in good to excellent yields. The reaction employs methyl tert-butyl ether (MTBE) as the methylene source and selectfluor as an oxidizing agent. The scope and versatility of the methods have been successfully demonstrated with 48 examples. The metal-free transformation process is suitable for scale-up production. A selectfluor-promoted oxidative reaction mechanism is proposed based on the results of the experimental studies.
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Affiliation(s)
- Jiang Jin
- College of Chemistry, Fuzhou University, Fuzhou, Fujian 350108, P. R. China
| | - Yinghua Li
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, China.
| | - Shiqun Xiang
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, China.
| | - Weibin Fan
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, China.
| | - Shiwei Guo
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, China.
| | - Deguang Huang
- College of Chemistry, Fuzhou University, Fuzhou, Fujian 350108, P. R. China and State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, China.
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Jha AK, Sarita, Easwar S. Unsymmetrical N,N'-functionalization of hydrazine by insertion into Morita–Baylis–Hillman ketones. Tetrahedron Lett 2021. [DOI: 10.1016/j.tetlet.2021.152971] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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