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Jamwal P, Nganthoinganbi Y, Tsai MK, Gurubrahamam R. Electrophilic Halogenation of Allenoates and 3-Alkynoates: Synthesis of 1,4-Dicarbonyl ( E)-3-Haloalkenes and Mechanistic Investigations. J Org Chem 2025; 90:4545-4559. [PMID: 40138471 DOI: 10.1021/acs.joc.4c02951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/29/2025]
Abstract
Allenoates traditionally provide halobutenolides upon reaction with halonium ions via electrophile-assisted halolactonization. Herein, an unusual electrophilic halogenation of di- and trisubstituted allenoates and 3-alkynoates is demonstrated with N-halosuccinimides under DABCO promotion. The protocol affords densely functionalized 1,4-dicarbonyl 3-haloalkenes in good yields with excellent (E)-stereoselectivity (up to 83% yield, >20:1 dr). The allenoates are presumed to form γ-haloallenoate intermediates, which further react with halonium ions and provide the desired scaffolds. The role of the nucleophilic base in the unusual transformation is demystified through control experiments and computational studies. The deliverables are identified as good synthons for various synthetic group transformations and valuable targets for biologically active pyridazine scaffolds.
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Affiliation(s)
- Paru Jamwal
- Department of Chemistry, Indian Institute of Technology Jammu, NH-44, PO Nagrota, Jagti, Jammu and Kashmir (J&K) 181221, India
| | - Yumnam Nganthoinganbi
- Department of Chemistry and Intelligent Computing for Sustainable Development Research Center, National Taiwan Normal University, Taipei 11677, Taiwan, R.O.C
| | - Ming-Kang Tsai
- Department of Chemistry and Intelligent Computing for Sustainable Development Research Center, National Taiwan Normal University, Taipei 11677, Taiwan, R.O.C
| | - Ramani Gurubrahamam
- Department of Chemistry, Indian Institute of Technology Jammu, NH-44, PO Nagrota, Jagti, Jammu and Kashmir (J&K) 181221, India
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Jamwal P, Sharma A, Gurubrahamam R. Decomposition of Alkynyl Hydrazones: Synthesis of Allenoates, Dihaloallenoates, and Angularly Fused Tricyclic Azepines. Org Lett 2023; 25:6607-6612. [PMID: 37669229 DOI: 10.1021/acs.orglett.3c01994] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/07/2023]
Abstract
An unprecedented decomposition of unprotected alkynyl hydrazones is attempted that has provided allenoates, tetrasubstituted α,γ-dihaloallenoates, and functionalized tricyclic azepines. A reaction of alkynyl hydrazones with N-halosuccinimides captures the electrophile in 2-fold that delivers fully substituted dibromo- and diiodoallenoates in good yields. In addition, a DABCO-promoted Wolff-Kishner reduction of hydrazones, followed by isomerization, provides versatile allenoates under mild conditions. In contrast, a similar decomposition with ambiphilic DBU furnishes a completely different tricyclic azepine scaffold in excellent yield and diastereoselectivity.
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Affiliation(s)
- Paru Jamwal
- Department of Chemistry, Indian Institute of Technology Jammu, NH-44, PO Nagrota, Jagti, Jammu, Jammu and Kashmir 181221, India
| | - Akashdeep Sharma
- Department of Chemistry, Indian Institute of Technology Jammu, NH-44, PO Nagrota, Jagti, Jammu, Jammu and Kashmir 181221, India
| | - Ramani Gurubrahamam
- Department of Chemistry, Indian Institute of Technology Jammu, NH-44, PO Nagrota, Jagti, Jammu, Jammu and Kashmir 181221, India
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Borra S, Kim HY, Oh K. One-Pot Tandem Nickel-Catalyzed α-Vinyl Aldol Reaction and Cycloaddition Approach to [1,2,3]Triazolo[1,5- a]quinolines. Org Lett 2023; 25:288-292. [PMID: 36580377 DOI: 10.1021/acs.orglett.2c04188] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
A one-pot tandem approach to [1,2,3]triazolo[1,5-a]quinolines was developed from (E)-β-chlorovinyl ketones and 2-azidoaryl carbonyls using a sequence of α-vinyl aldol and azide-alkyne cycloaddition reactions. In particular, the intramolecular azide-alkyne cycloaddition of allenol intermediates was readily promoted by a synergistic action of NEt3 and nickel catalysts. Given that the [1,2,3]triazolo[1,5-a]quinolines are useful synthetic precursors to α-diazoimines through ring-chain isomerization process, the subsequent denitrogenative transformations should provide ready access to valuable heterocyclic compounds.
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Affiliation(s)
- Satheesh Borra
- Center for Metareceptome Research, Graduate School of Pharmaceutical Sciences, Chung-Ang University, 84 Heukseok-ro, Dongjak, Seoul 06974, Republic of Korea
| | - Hun Young Kim
- Department of Global Innovative Drugs, Chung-Ang University, 84 Heukseok-ro, Dongjak, Seoul 06974, Republic of Korea
| | - Kyungsoo Oh
- Center for Metareceptome Research, Graduate School of Pharmaceutical Sciences, Chung-Ang University, 84 Heukseok-ro, Dongjak, Seoul 06974, Republic of Korea
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Borra S, Chae S, Kim HY, Oh K. Continuous Flow Synthesis of 1,4-Benzothiazines Using Ambivalent Reactivity of ( E)-β-Chlorovinyl Ketones: A Point of Reaction Control Enabled by Flow Chemistry. Org Lett 2022; 24:5287-5292. [PMID: 35848887 DOI: 10.1021/acs.orglett.2c01865] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
A continuous flow system to 1,4-benzothiazines was developed using the point of reaction control, where the ambivalent (E)-β-chlorovinyl ketones and 2,2'-dithiodianilines were confined in a diffusion controlled flow setting. The successful segregation of reactive chemical species in a flow setting allowed more defined reaction pathways that are not feasible in traditional batch reaction conditions. The point of reaction control in flow systems helps to execute the reactions often plagued with the concurrent generation of multiple chemical species.
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Affiliation(s)
- Satheesh Borra
- Center for Metareceptome Research, Graduate School of Pharmaceutical Sciences, Chung-Ang University, 84 Heukseok-ro, Dongjak, Seoul 06974, Republic of Korea
| | - Soyeon Chae
- Department of Global Innovative Drugs, Chung-Ang University, 84 Heukseok-ro, Dongjak, Seoul 06974, Republic of Korea
| | - Hun Young Kim
- Department of Global Innovative Drugs, Chung-Ang University, 84 Heukseok-ro, Dongjak, Seoul 06974, Republic of Korea
| | - Kyungsoo Oh
- Center for Metareceptome Research, Graduate School of Pharmaceutical Sciences, Chung-Ang University, 84 Heukseok-ro, Dongjak, Seoul 06974, Republic of Korea
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Bhatt D, Chae S, Kim HY, Oh K. One-Pot Synthesis of N-Hydroxypyrroles via Soft α-Vinyl Enolization of ( E)-β-Chlorovinyl Ketones: A Traceless Arylsulfinate Mediator Strategy. Org Lett 2022; 24:2636-2640. [PMID: 35385289 DOI: 10.1021/acs.orglett.2c00649] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
A traceless arylsulfinate mediator strategy has been developed to switch the reaction course of β-chlorovinyl ketones with N-hydroxyamine. The soft α-vinyl enolization of (E)-β-chlorovinyl ketones was conducted in the presence of sodium arylsulfinate to give transient alkenyl sulfones that in turn reacted with NH2OH to give novel access to N-hydroxypyrroles. The mechanistic studies revealed the initial formation of oxazine intermediates that rearranged to thermodynamically stable aromatic products, N-hydroxypyrroles, under microwave-assisted heating conditions.
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Affiliation(s)
- Divya Bhatt
- Center for Metareceptome Research, Graduate School of Pharmaceutical Sciences, Chung-Ang University, 84 Heukseok-ro, Dongjak, Seoul 06974, Republic of Korea
| | - Soyeon Chae
- Department of Global Innovative Drugs, Chung-Ang University, 84 Heukseok-ro, Dongjak, Seoul 06974, Republic of Korea
| | - Hun Young Kim
- Department of Global Innovative Drugs, Chung-Ang University, 84 Heukseok-ro, Dongjak, Seoul 06974, Republic of Korea
| | - Kyungsoo Oh
- Center for Metareceptome Research, Graduate School of Pharmaceutical Sciences, Chung-Ang University, 84 Heukseok-ro, Dongjak, Seoul 06974, Republic of Korea
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