Synthetic Methods for the Preparation of Norcarane Scaffolds. A Review

Eugui, Macarena; Parpal, Florencia; Radcenco, Andrés López; Moyna, Guillermo

doi:10.1080/00304948.2018.1462048

Cited by 5 publications

(3 citation statements)

References 94 publications

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“…Based on preceding photochemical transformations, we believed that the dihydrohomobarrelenones 4 would be eligible for photoisomerizations, forming complex polycyclic compounds . The formed norcarane derivates would include fully substituted chiral cyclopropanes, which are often considered challenging synthetic targets . To our delight, the photoisomerization proceeded smoothly when subjecting a mixture of cycloadduct 4 e / 4 e′ to light in CHCl 3 (3 x 3 W, 365 ± 5 nm), yielding the tetracyclic norcarane 8 in 47 % yield, >20:1 d.r., and maintaining the enantiomeric excess (Scheme a).…”

Section: Figurementioning

confidence: 96%

Catalytic Asymmetric [4+2]‐Cycloadditions Using Tropolones: Developments, Scope, Transformations, and Bioactivity

et al. 2018

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An organocatalyzed asymmetric [4+ +2]-cycloaddition between tropolones and electron-deficient dienophiles is presented. Complex and biologically interesting dihydrohomobarrelenone scaffolds are formed through aD iels-Alder reaction utilizing bifunctional Brønsted-base catalysis,affording the corresponding bridged bicyclic cycloadducts in up to quantitative yields with good enantio-(up to 92 %e e) and diastereoselectivity (up to > 20:1 d.r.). The synthetic value of the obtained products is explored by downstream transformations,i ncluding photoisomerizations,a nd their biological relevancy by in vivo testing in MCF-7 cancer cells.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

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Section: Figurementioning

confidence: 96%

Catalytic Asymmetric [4+2]‐Cycloadditions Using Tropolones: Developments, Scope, Transformations, and Bioactivity

et al. 2018

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“…[5d, 11] Thef ormed norcarane derivates would include fully substituted chiral cyclopropanes,w hich are often considered challenging synthetic targets. [12] To our delight, the photoisomerization proceeded smoothly when subjecting amixture of cycloadduct 4e/4e' ' to light in CHCl 3 (3 x3W, 365 AE 5n m), yielding the tetracyclic norcarane 8 in 47 %y ield, > 20:1 d.r.,a nd maintaining the enantiomeric excess (Scheme 7a).…”

Section: Methodsmentioning

confidence: 91%

Catalytic Asymmetric [4+2]‐Cycloadditions Using Tropolones: Developments, Scope, Transformations, and Bioactivity

et al. 2018

View full text Add to dashboard Cite

An organocatalyzed asymmetric [4+2]-cycloaddition between tropolones and electron-deficient dienophiles is presented. Complex and biologically interesting dihydrohomobarrelenone scaffolds are formed through a Diels-Alder reaction utilizing bifunctional Brønsted-base catalysis, affording the corresponding bridged bicyclic cycloadducts in up to quantitative yields with good enantio- (up to 92 % ee) and diastereoselectivity (up to >20:1 d.r.). The synthetic value of the obtained products is explored by downstream transformations, including photoisomerizations, and their biological relevancy by in vivo testing in MCF-7 cancer cells.

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“…This reaction sequence accomplishes the formation of three new C–C bonds to achieve the norcarane structure with up to five stereocenterswith two being all carbon quaternary stereocenters at ring junctions . The formed structural scaffold can be used to generate complex ring structures through simple transformations ( vide infra ), and its norcarane ring core is a structural element present in naturally occurring products such as merulactone and (−)-sterepolide (Scheme , green) …”

mentioning

confidence: 99%

Asymmetric Organocatalyzed Cascade Reactions─Merging the pseudo-Halogen and Halogen Effect with Dienamine Catalysis

et al. 2023

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The combination of asymmetric organocatalysis with the (pseudo)-halogen effect enables the formation of chiral norcarane scaffolds in high yields and selectivities (up to 92% yield, >99% ee, and >95:5 d.r.). This was achieved by reacting (pseudo)-halogenated 3-vinyl chromones with in situ generated chiral dienamines in an inverse electron demand [4 + 2] cycloaddition followed by an intramolecular S N 2 reaction. These scaffolds could easily undergo photoinduced rearrangements or lactonization to form intricate chiral ring structures.

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Synthetic Methods for the Preparation of Norcarane Scaffolds. A Review

Cited by 5 publications

References 94 publications

Catalytic Asymmetric [4+2]‐Cycloadditions Using Tropolones: Developments, Scope, Transformations, and Bioactivity

Catalytic Asymmetric [4+2]‐Cycloadditions Using Tropolones: Developments, Scope, Transformations, and Bioactivity

Catalytic Asymmetric [4+2]‐Cycloadditions Using Tropolones: Developments, Scope, Transformations, and Bioactivity

Asymmetric Organocatalyzed Cascade Reactions─Merging the pseudo-Halogen and Halogen Effect with Dienamine Catalysis

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