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Das D, Pingoliya RK, Ghorai P. A One-Pot Cascade Strategy toward Organocatalytic Enantioselective Construction of Fused Benzimidazoles. Org Lett 2024; 26:4502-4507. [PMID: 38767405 DOI: 10.1021/acs.orglett.4c01336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Herein, we describe an asymmetric assembly of ortho-aromatic diamines and formyl tethered Michael acceptors forming chiral fused benzimidazoles. A cinchona-alkaloid-derived bifunctional squaramide catalyst enables the methodology through on-site dihydrobenzimidazole formation followed by an aza-Michael addition/oxidation cascade. This protocol stands out for its excellent catalytic efficiency over the background reaction and its mild conditions, making it more practical. Various Michael acceptors, including enones, ester, and thioester, were successful substrates in this study. Additionally, this methodology has demonstrated scalability and successfully showcased postsynthetic transformations.
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Affiliation(s)
- Dipankar Das
- Department of Chemistry, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal By-pass Road, Bhauri, Bhopal-462066, India
| | - Rahul Kumar Pingoliya
- Department of Chemistry, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal By-pass Road, Bhauri, Bhopal-462066, India
| | - Prasanta Ghorai
- Department of Chemistry, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal By-pass Road, Bhauri, Bhopal-462066, India
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2
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Han JW, Kim Y, Kim SG. Organocatalytic Asymmetric [4 + 2]-Cycloadditions of 2-Aminophenyl Enones with Isatin-Derived Ketimines: Diastereo- and Enantioselective Synthesis of Spirooxindole-Tetrahydroquinazolines. Org Lett 2024; 26:252-257. [PMID: 38147651 DOI: 10.1021/acs.orglett.3c03918] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2023]
Abstract
A novel method for the enantioselective synthesis of spiro N,N-heterocyclic oxindoles has been developed, employing asymmetric [4 + 2]-cycloadditions of 2-aminophenyl enones with isatin-derived ketimines. This method employs an organocatalytic approach, utilizing a bifunctional squaramide-based catalyst. It enables the precise synthesis of chiral spirooxindole-tetrahydroquinazolines with intricate structures, featuring chiral quaternary centers. This process achieves remarkable results, including high yields and exceptional levels of enantioselectivity and diastereoselectivity (up to 96% yield, 95% ee, and >20:1 dr).
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Affiliation(s)
- Ji Won Han
- Department of Chemistry, College of Natural Science, Kyonggi University, 154-42, Gwanggyosan-ro, Yeongtong-gu, Suwon, 16227, Republic of Korea
| | - Yoseop Kim
- Department of Chemistry, College of Natural Science, Kyonggi University, 154-42, Gwanggyosan-ro, Yeongtong-gu, Suwon, 16227, Republic of Korea
| | - Sung-Gon Kim
- Department of Chemistry, College of Natural Science, Kyonggi University, 154-42, Gwanggyosan-ro, Yeongtong-gu, Suwon, 16227, Republic of Korea
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3
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Parida C, Pan SC. Organocatalytic Synthesis of Furan-Embedded Styrene Atropisomers. J Org Chem 2023; 88:13358-13370. [PMID: 37675791 DOI: 10.1021/acs.joc.3c01391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/08/2023]
Abstract
Herein, we report the first synthesis of furan-embedded styrene atropisomers via the reaction between 1-(aryl-ethynyl)-naphthalen-2-ol and γ-hydroxyenone. The reaction proceeds through in situ furan formation from γ-hydroxyenone. The styrene derivatives were obtained in moderate to good yields with high diastereoselectivities with a catalytic amount of PTSA. Few applications such as triazole formation and cross-coupling reactions have been demonstrated. A preliminary catalytic asymmetric version was also reported.
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Affiliation(s)
- Chandrakanta Parida
- Department of Chemistry, Indian Institute of Technology Guwahati, North Guwahati, Assam 781039, India
| | - Subhas Chandra Pan
- Department of Chemistry, Indian Institute of Technology Guwahati, North Guwahati, Assam 781039, India
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4
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Gil-Ordóñez M, Martín L, Maestro A, Andrés JM. Organocatalytic asymmetric synthesis of oxazolidino spiropyrazolinones via N, O-acetalization/aza Michael addition domino reaction between N-Boc pyrazolinone ketimines and γ-hydroxyenones. Org Biomol Chem 2023; 21:2361-2369. [PMID: 36847380 DOI: 10.1039/d2ob02290g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
A squaramide-catalyzed asymmetric N,O-acetalization/aza Michael addition domino reaction between N-Boc ketimines derived from pyrazolin-5-ones and γ-hydroxyenones has been developed for the construction of pyrazolinone embedded spirooxazolidines. A hydroquinine derived bifunctional squaramide catalyst was found to be the most effective for this cascade spiroannulation. This new protocol allows the generation of two stereocenters and the desired products are obtained in good yields with moderate to good diastereoselectivities (up to 3.3 : 1 dr) and high enantioselectivities (up to >99% ee) from a range of substituted N-Boc pyrazolinone ketimines and γ-hydroxyenones. The developed protocol is amenable for a scale-up reaction.
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Affiliation(s)
- Marta Gil-Ordóñez
- GIR-SintACat-Instituto Universitario CINQUIMA y Departamento de Química Orgánica, Facultad de Ciencias, Universidad de Valladolid, Paseo Belén 7, 47011 Valladolid, Spain.
| | - Laura Martín
- GIR-SintACat-Instituto Universitario CINQUIMA y Departamento de Química Orgánica, Facultad de Ciencias, Universidad de Valladolid, Paseo Belén 7, 47011 Valladolid, Spain.
| | - Alicia Maestro
- GIR-SintACat-Instituto Universitario CINQUIMA y Departamento de Química Orgánica, Facultad de Ciencias, Universidad de Valladolid, Paseo Belén 7, 47011 Valladolid, Spain.
| | - José M Andrés
- GIR-SintACat-Instituto Universitario CINQUIMA y Departamento de Química Orgánica, Facultad de Ciencias, Universidad de Valladolid, Paseo Belén 7, 47011 Valladolid, Spain.
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Kim Y, Kim SY, Kim SG. Organocatalytic Asymmetric [3 + 2]-Annulations of γ-Sulfonamido/γ-Hydroxy-α,β-Unsaturated Ketones with Cyclic N-Sulfimines: Synthesis of Chiral Polyheterotricyclic Imidazolidines and Oxazolidines. J Org Chem 2023; 88:1113-1127. [PMID: 36580571 DOI: 10.1021/acs.joc.2c02634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The first organocatalytic asymmetric [3 + 2]-annulation of γ-sulfonamido-α,β-unsaturated ketones with cyclic N-sulfimines has been developed, and enantioenriched functionalized polyheterotricyclic imidazolidines were obtained in good yields and with excellent enantioselectivities. This approach was also extended to the asymmetric [3 + 2]-annulation of γ-hydroxy-α,β-unsaturated ketones, affording enantioenriched polyheterotricyclic oxazolidines. In addition, base-catalyzed [3 + 2]-annulations of γ-sulfonamido/γ-hydroxy-α,β-unsaturated ketones with cyclic N-sulfimines were re-investigated under mild reaction conditions for the synthesis of racemic polyheterotricyclic imidazolidines and oxazolidines with excellent diastereoselectivities.
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Affiliation(s)
- Yoseop Kim
- Department of Chemistry, College of Natural Science, Kyonggi University, 154-42 Gwanggyosan-ro, Yeongtong-gu, Suwon 16227, Republic of Korea
| | - Seung Yeon Kim
- Department of Chemistry, College of Natural Science, Kyonggi University, 154-42 Gwanggyosan-ro, Yeongtong-gu, Suwon 16227, Republic of Korea
| | - Sung-Gon Kim
- Department of Chemistry, College of Natural Science, Kyonggi University, 154-42 Gwanggyosan-ro, Yeongtong-gu, Suwon 16227, Republic of Korea
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Shukla K, Khushboo, Mahto P, Singh VK. Enantioselective synthesis of tetrahydrofuran spirooxindoles via domino oxa-Michael/Michael addition reaction using a bifunctional squaramide catalyst. Org Biomol Chem 2022; 20:4155-4160. [PMID: 35521781 DOI: 10.1039/d2ob00633b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An enantioselective approach for the synthesis of tetrahydrofuran spirooxindoles via domino oxa-Michael/Michael addition reaction of γ-hydroxyenones to isatylidene malononitriles, using a cinchona derived bifunctional squaramide catalyst has been developed. The methodology is the first success of enantioselective oxa-Michael addition to isatylidene malononitriles. The spiro products were obtained in excellent yields with moderate to good enantio- and diastereoselectivities. Scale-up of the reaction and synthetic transformation of the spiro product into structurally complex molecules have been performed.
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Affiliation(s)
- Khyati Shukla
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208 016, India.
| | - Khushboo
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208 016, India.
| | - Pratibha Mahto
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208 016, India.
| | - Vinod K Singh
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208 016, India.
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