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Recent Advances in Oxa-6π Electrocyclization Reactivity for the Synthesis of Privileged Natural Product Scaffolds. ORGANICS 2021. [DOI: 10.3390/org2040021] [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 stunning advances in understanding the reactivity and selectivity principles of asymmetric pericyclic reactions have had a profound impact on the synthetic planning of complex natural products. Indeed, electrocyclizations, cycloadditions, and sigmatropic rearrangements enable synthetic chemists to craft highly functionalized scaffolds that would not otherwise be possible with a similar atom-, step-, and redox-economy. In this review, selected examples from the last two decades of research (2003–2020) on tandem processes combining oxa-6π electrocyclic reactions are discussed in terms of reactivity challenges, inherent reversibility, and key structural bond formation in the assembly of natural products. A particular emphasis is given to the electrocyclic ring-closures in the tandem processes featuring Knoevenagel-type condensations, Diels–Alder cycloadditions, Stille couplings, and oxidative dearomatizations. The synthetic manifolds reviewed here illustrate how oxa-6π electrocyclizations are intimately linked to the construction of complex natural product scaffolds and have inspired a number of biomimetic syntheses in the laboratory.
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Shao HQ, Wang YX, Sun HY, Wang YC, Sun WJ. Crystal structure of 1,4-bis(4-bromobenzyl)-4-(4-chlorophenyl)-1,4-dihydropyridine-3-carbonitrile, C 26H 19Br 2ClN 2. Z KRIST-NEW CRYST ST 2021. [DOI: 10.1515/ncrs-2021-0068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
C26H19Br2ClN2, triclinic, P
1
‾
$‾{1}$
(no. 2), a = 9.4830(12) Å, b = 10.2313(12) Å, c = 13.5948(18) Å, α = 111.234(2)°, β = 98.025(2)°, γ = 101.707(2)°, V = 1170.6(3) Å3, Z = 2, R
gt
(F) = 0.0444, wR
ref
(F
2) = 0.1273, T = 296 K.
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Affiliation(s)
- Han-Qiao Shao
- School of Pharmacy, North China University of Science and Technology , 063210, Caofeidian District , Tangshan , P. R. China
| | - Yin-Xin Wang
- School of Pharmacy, North China University of Science and Technology , 063210, Caofeidian District , Tangshan , P. R. China
| | - Hai-Yang Sun
- School of Pharmacy, North China University of Science and Technology , 063210, Caofeidian District , Tangshan , P. R. China
| | - Yu-Cai Wang
- School of Continuing Education, Jiamusi University , No. 148 Xuefu St. , Jiamusi , Heilongjiang , P. R. China
| | - Wu-Ji Sun
- School of Pharmacy, North China University of Science and Technology , 063210, Caofeidian District , Tangshan , P. R. China
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Quindt MI, Gola GF, Ramirez JA, Bonesi SM. Photochemical Behavior of Some Estrone Aryl and Methyl Sulfonates in Solution: Preparative and Mechanistic Studies. Photochem Photobiol 2020; 97:8-21. [PMID: 32246460 DOI: 10.1111/php.13272] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 03/23/2020] [Indexed: 11/28/2022]
Abstract
Direct irradiation of estrone aryl and methyl sulfonates in different organic solvents under nitrogen atmosphere was investigated under steady-state conditions. The estrone derivatives reacted efficiently through the photo-Fries rearrangement reaction involving [1;3]-sulfonyl migration providing the ortho-sulfonyl estrone derivatives and estrone as the photoproducts. In addition, estrone and 2-arylsulfonyl estrone derivatives were epimerized involving a Norrish Type-I reaction. Chemical quenching and photosensitization experiments on the photoreaction have been also carried out to establish the photoreactive excited state. Likewise, the solvent effect and the nature of the sulfonyl group on the photoreactions have been also studied.
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Affiliation(s)
- Matías I Quindt
- Facultad de Ciencias Exactas y Naturales, Departamento de Química Orgánica, Universidad de Buenos Aires, Buenos Aires, Argentina.,Centro de Investigaciones en Hidratos de Carbono (CIHIDECAR), CONICET - Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Gabriel F Gola
- Facultad de Ciencias Exactas y Naturales, Departamento de Química Orgánica, Universidad de Buenos Aires, Buenos Aires, Argentina.,Unidad de Microanálisis y Métodos Físicos Aplicados a Química Orgánica (UMYMFOR), CONICET - Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Javier A Ramirez
- Facultad de Ciencias Exactas y Naturales, Departamento de Química Orgánica, Universidad de Buenos Aires, Buenos Aires, Argentina.,Unidad de Microanálisis y Métodos Físicos Aplicados a Química Orgánica (UMYMFOR), CONICET - Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Sergio M Bonesi
- Facultad de Ciencias Exactas y Naturales, Departamento de Química Orgánica, Universidad de Buenos Aires, Buenos Aires, Argentina.,Centro de Investigaciones en Hidratos de Carbono (CIHIDECAR), CONICET - Universidad de Buenos Aires, Buenos Aires, Argentina
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Quindt MI, Gola GF, Ramirez JA, Bonesi SM. Photo-Fries Rearrangement of Some 3-Acylestrones in Homogeneous Media: Preparative and Mechanistic Studies. J Org Chem 2019; 84:7051-7065. [DOI: 10.1021/acs.joc.9b00786] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Matías I. Quindt
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Química Orgánica, Buenos Aires, C1428EGA, Argentina
- CONICET−Universidad de Buenos Aires, Centro de Investigaciones en Hidratos de Carbono (CIHIDECAR), Buenos Aires, C1428EGA, Argentina
| | - Gabriel F. Gola
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Química Orgánica, Buenos Aires, C1428EGA, Argentina
- CONICET−Universidad de Buenos Aires, Unidad de Microanálisis y Métodos Físicos Aplicados a Química Orgánica (UMYMFOR), Buenos Aires, C1428EHA, Argentina
| | - Javier A. Ramirez
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Química Orgánica, Buenos Aires, C1428EGA, Argentina
- CONICET−Universidad de Buenos Aires, Unidad de Microanálisis y Métodos Físicos Aplicados a Química Orgánica (UMYMFOR), Buenos Aires, C1428EHA, Argentina
| | - Sergio M. Bonesi
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Química Orgánica, Buenos Aires, C1428EGA, Argentina
- CONICET−Universidad de Buenos Aires, Centro de Investigaciones en Hidratos de Carbono (CIHIDECAR), Buenos Aires, C1428EGA, Argentina
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