Six‐Membered Rings with One Oxygen: Pyrylium Ion, Related Systems and Benzo‐Derivatives

Santamarı́a, Javier; Valdés, Carlos

doi:10.1002/9783527637737.ch18

Cited by 19 publications

(5 citation statements)

References 186 publications

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“…One of the most employed methods for the synthesis of chromones involves the reaction of ortho-hydroxyacetophenones with several acid anhydrides, followed by intra-molecular cyclization and subsequent dehydration [15][16][17][18]. The preparation of new 2-trifluoromethylchromones using the above method with trifluoroacetic ethyl ester has been reported by Sosnovskikh's group [19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

A detailed experimental and theoretical study of two novel substituted trifluoromethylchromones. The influence of the bulky bromine atom on the crystal packing

León

Echeverría

Piro

et al. 2015

Spectrochimica Acta Part A: Molecular and Biomolecular Spectros

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The new 3-methyl-2-trifluoromethylchromone (1) and 3-bromomethyl-2-trifluoromethylchromone (2) compounds were synthesized and characterized by vibrational (IR, Raman), UV-Vis and NMR ((1)H, (13)C and (19)F) spectroscopy and MS spectrometry. The crystal structures of 1 and 2 were determined by X-ray diffraction methods. Both compounds crystallize in the monoclinic P21/c space group with Z=4 molecules per unit cell. The structures were solved from 1423 (1) and 1856 (2) reflections with I>2σ (I) and refined by full-matrix least-squares to agreement R1-values of 0.0403 (1) and 0.0554 (2). Because of π-bonding delocalization, the organic molecular skeletons are planar and the molecular bonding structures can be described by formally single, double and resonant bonds. In 2, the CF3 group revealed a strong rotational disorder around the CCF3 bond, which could be explained in terms of four split positions with about uniform angular distribution. The vibrational, electronic and NMR, spectra were discussed and assigned with the assistance of DFT calculations.

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Section: Introductionmentioning

confidence: 99%

A detailed experimental and theoretical study of two novel substituted trifluoromethylchromones. The influence of the bulky bromine atom on the crystal packing

León

Echeverría

Piro

et al. 2015

Spectrochimica Acta Part A: Molecular and Biomolecular Spectros

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“…Isobenzopyrylium ions have emerged as a unique type of reactive cyclic oxonium intermediates that have been shown to participate in a range of cascade reactions affording natural products and bioactive molecules . In contrast, catalytic enantioselective cascade reactions with isobenzopyrylium ions remain significantly less developed .…”

Section: Introductionmentioning

confidence: 99%

“…2 Isobenzopyrylium ions have emerged as a unique type of reactive cyclic oxonium intermediates that have been shown to participate in a range of cascade reactions affording natural products and bioactive molecules. 3 In contrast, catalytic enantioselective cascade reactions with isobenzopyrylium ions remain significantly less developed. 4 The inherent challenges in their use arises from the high reactivity, aromatic planar structure, and the lack of a Lewis basic site needed for interactions with a potential catalyst.…”

Section: ■ Introductionmentioning

confidence: 99%

Organocatalytic Asymmetric Multicomponent Cascade Reaction for the Synthesis of Contiguously Substituted Tetrahydronaphthols

et al. 2021

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Isobenzopyrylium ions are unique, highly reactive, aromatic intermediates which are largely unexplored in asymmetric catalysis despite their high potential synthetic utility. In this study, an organocatalytic asymmetric multicomponent cascade via dienamine catalysis, involving a cycloaddition, a nucleophilic addition, and a ring-opening reaction, is disclosed. The reaction furnishes chiral tetrahydronaphthols containing four contiguous stereocenters in good to high yield, high diastereoselectivity (up to >20:1), and excellent enantioselectivity (93−98% ee). The obtained products are important synthetic intermediates, and it is demonstrated that they can be used for the generation of frameworks such as octahydrobenzo[h]isoquinoline and [2.2.2]octane scaffolds. Furthermore, mechanistic experiments involving oxygen-18-labeling studies and density functional theory calculations provide a vivid picture of the reaction mechanism. Finally, the bioactivity of 16 representative tetrahydronaphthol compounds has been evaluated in U-2OS cancer cells with some compounds showing a unique profile and a clear morphological change.

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“…The pyrylium salts have been classically employed as photosensitizers in the photoinduced electron transfer (PET) mediated cycloadditions . Further, pyrylium salts or pyrylium intermediates have also found use as dienes in the hetero-Diels–Alder reactions and as dipolarophiles in cycloaddition reactions . However, to the best of our knowledge, there is no report suggesting the dual role of pyrylium salts as photosensitizer and dipolarophile in a 1,3-dipolar cycloaddition sequence.…”

Section: Introductionmentioning

confidence: 99%

Redox-Neutral 1,3-Dipolar Cycloaddition of 2H-Azirines with 2,4,6-Triarylpyrylium Salts under Visible Light Irradiation

et al. 2021

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A novel visible light mediated redox-neutral 1,3-dipolar cycloaddition of 2H-azirines with 2,4,6-triarylpyrylium tetrafluoroborate salts providing tetrasubstituted pyrroles has been developed. The 2,4,6-triarylpyrylium salt acts as dipolarophile as well as photosensitizer in the reaction, under blue light irradiation. The control experiments indicated single electron oxidation of 2H-azirines by photoexcited pyrylium salts, followed by coupling between an azaallenyl radical cation and triarylpyranyl radical as the key mechanistic feature. The mild conditions, wide substrate scope, and complete regioselectivity are the noticeable attributes of the reaction.

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Six‐Membered Rings with One Oxygen: Pyrylium Ion, Related Systems and Benzo‐Derivatives

Cited by 19 publications

References 186 publications

A detailed experimental and theoretical study of two novel substituted trifluoromethylchromones. The influence of the bulky bromine atom on the crystal packing

A detailed experimental and theoretical study of two novel substituted trifluoromethylchromones. The influence of the bulky bromine atom on the crystal packing

Organocatalytic Asymmetric Multicomponent Cascade Reaction for the Synthesis of Contiguously Substituted Tetrahydronaphthols

Redox-Neutral 1,3-Dipolar Cycloaddition of 2H-Azirines with 2,4,6-Triarylpyrylium Salts under Visible Light Irradiation

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