Enyne [4 + 4] photocycloaddition with polycyclic aromatics

Khatri, Buddha B.; Kulyk, Svitlana; Sieburth, Scott McN.

doi:10.1039/c4qo00190g

Cited by 11 publications

(10 citation statements)

References 18 publications

(18 reference statements)

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“…10 Photo cycloadditions to arenes complement nicely these methods leading to diverse products topology, Scheme 1. 11 Among these, the [3+2] reactions 12 were often used as key steps in the synthesis of natural products, 13 while the [2+2], 14 [4+2], 15 and [4+4] 16 cycloadditions of arenes remain somewhat underutilized. Furthermore, [2+4] photocycloadditions – with arene acting as a 2π “dienophile” – are unknown.…”

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confidence: 99%

Photoassisted Synthesis of Complex Molecular Architectures: Dearomatization of Benzenoid Arenes with Aza‐o‐xylylenes via an Unprecedented [2+4] Reaction Topology

2016

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A new method for photoinduced dearomatization of arenes via an intramolecular cycloaddition with aza-o-xylylenes generated by the excited-state intramolecular proton transfer (ESIPT) in the readily available photoprecursors is developed. The topology of this cycloaddition, [2+4], is unprecedented for photo-dearomatizations of benzenoid aromatic carbocycles. It provides rapid access to novel heterocycles, cyclohexadieno-oxazolidino-quinolinols, as valuable synthons for a broad range of postphotochemical transformations.

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confidence: 99%

Photoassisted Synthesis of Complex Molecular Architectures: Dearomatization of Benzenoid Arenes with Aza‐o‐xylylenes via an Unprecedented [2+4] Reaction Topology

2016

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“…1 → 3 , Scheme ). Recently we reported that 1,3‐enynes can be participants in [4+4] cycloadditions and found them to work well with pyridones ( 4 , 7 ), pyrones and anthracene . The cycloadducts formed in these higher‐order cycloadditions are incapable of isomerizing to arenes however, and unless an alternative pathway to relieve strain is available, the products often undergo dimerization reactions that result in complex mixtures …”

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confidence: 99%

Enyne [4+4] Cycloaddition/Oxidation: Ring Contraction via Cyclopropanones and Their Anionic Ring‐Opening Reactions

2016

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Irradiation of a 1,3‐enyne tethered to a 2‐pyridone, in the presence of oxygen, leads to formation of a seven‐membered ring product, an overall [4+4−1] reaction. This transformation involves two unstable intermediates and a sequence of unusual reactions. An initial [4+4] photocycloaddition of the enyne with the pyridone yields a 1,2,5‐cyclooctatriene. Photooxidation of this triene forms a cyclopropanone and subsequent photoextrusion of carbon monoxide gives the observed 1,4‐cycloheptadiene product. The first‐formed cyclooctatriene and the cyclopropanone could be observed and characterized spectroscopically. The cyclopropanone underwent CO extrusion both photochemically and thermally to give the cycloheptadiene product. Addition of fluoride or acetylide to the most stable cyclopropanone occurred chemoselectively at the two different silicon groups rather than the carbonyl group. The resulting cyclopropanone ring openings gave unsaturated aldehydes.

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“…8 For example, anthracene undergoes a rapid intramolecular cycloaddition with 2-pyridone give 2, Scheme 1. 9 Similarly, a 1-naphthyl group yields a mixture of diastereomers 4 and 5. 10 In contrast, a tethered benzene (6) is inert to these conditions and dimers of the pyridone are the only observed products.…”

Section: Introductionmentioning

confidence: 99%

Photo-[4+4]-cycloaddition (para) of meta-substituted benzenes with 2-pyridones

Khatri

Vrubliauskas

Sieburth

2015

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a b s t r a c tBenzene is unreactive as a photochemistry partner with 2-pyridone, however benzene substitution can allow for an efficient [4+4] (a k a, 'para') photocycloaddition. Productive substituents include alkoxy, cyano, ester, and trifluoromethyl, suggesting that inductively electron-withdrawing groups are sufficient, however a single fluorine substituent does not result in cycloaddition. When the product of this cycloaddition contains a conjugated system (e.g., an unsaturated ester) a secondary photocycloaddition can follow, forming triply bridged all-syn-[3]ladderane products.

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Enyne [4 + 4] photocycloaddition with polycyclic aromatics

Abstract: Polycyclic aromatics undergo [4 + 4] photocycloaddition to give tricyclic polyene products.

Cited by 11 publications

References 18 publications

Photoassisted Synthesis of Complex Molecular Architectures: Dearomatization of Benzenoid Arenes with Aza‐o‐xylylenes via an Unprecedented [2+4] Reaction Topology

Photoassisted Synthesis of Complex Molecular Architectures: Dearomatization of Benzenoid Arenes with Aza‐o‐xylylenes via an Unprecedented [2+4] Reaction Topology

Enyne [4+4] Cycloaddition/Oxidation: Ring Contraction via Cyclopropanones and Their Anionic Ring‐Opening Reactions

Photo-[4+4]-cycloaddition (para) of meta-substituted benzenes with 2-pyridones

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