7-Dimethylvinylidene-1-methoxybicyclo[4.1.0]heptane and Ethyl 1-Ethoxy-2-methylcyclopropane-3-carboxylate

Wenkert, Ernest; Chou, Kechia J.; Hatch, Robert P.

doi:10.1080/00397917708050767

Cited by 12 publications

(3 citation statements)

References 5 publications

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“…The ability of silicon to stabilize an α‐anion is well known, but the extent of this stabilization is limited . The absence of stereochemistry at the cyclopropanone carbonyl of 14 unfortunately does not allow a study of a conrotatory ring‐opening pathway for this cyclopropanone …”

Section: Methodsmentioning

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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Section: Methodsmentioning

confidence: 99%

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

2016

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“…Forr ingopening products from 14,asilicon group is the sole anionstabilizing substituent. [29,31] Fort he unusual 1,2,5-cyclooctatrienes discussed here, oxidation of the allene,e ither with dioxirane or by photocycloaddition in the presence of oxygen, results in isomerization to the corresponding cyclopropanone.W eh ave not observed oxidation of the more stable allenes,s uch as 8,o n exposure to oxygen in the absence of light. [30] Theabsence of stereochemistry at the cyclopropanone carbonyl of 14 unfortunately does not allow as tudy of ac onrotatory ring-opening pathway for this cyclopropanone.…”

Section: Angewandte Chemiementioning

confidence: 98%

“…[30] Theabsence of stereochemistry at the cyclopropanone carbonyl of 14 unfortunately does not allow as tudy of ac onrotatory ring-opening pathway for this cyclopropanone. [29,31] Fort he unusual 1,2,5-cyclooctatrienes discussed here, oxidation of the allene,e ither with dioxirane or by photocycloaddition in the presence of oxygen, results in isomerization to the corresponding cyclopropanone.W eh ave not observed oxidation of the more stable allenes,s uch as 8,o n exposure to oxygen in the absence of light. Expulsion of carbon monoxide,either photochemically or through heating, leads to formation of ac ycloheptadiene.O verall, the threestep transformation with loss of ar ing carbon represents a[4+ +4À1] combination of an enyne with a2-pyridone to yield aseven-membered ring.…”

Section: Angewandte Chemiementioning

confidence: 98%

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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Gasphasensynthese reaktiver Moleküle mit adsorbierten Reagentien

Billups

McCord

1994

Angewandte Chemie

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Baseninduzierte Eliminierungen haben für die Synthese gespannter Alkene breite Anwendung gefunden. Diese Methode wird häufig durch eine Konkurrenzreaktion erschwert, beider das anfänglich gebildete Alken durch nucleophile Addition der Base abgefangen wird. Neuere Untersuchungen haben gezeigt, daß bimolekulare Nebenreaktionen vermieden werden können, wenn Basen wie Kalium‐tert‐butylalkoholat auf einen Träger mit inerter Oberfläche wie Kieselgel aufgebracht sind und die Umsetzung im Vakuum durchgeführt wird. Dieses VGSR‐Verfahren (VGSR = vacuum gas‐solid reaction) hat außerdem den Vorteil, daß sehr instabile Verbindungen unter Bedingungen isoliert werden können, bei denen sich ihre physikalischen und chemischen Eigenschaften untersuchen lassen. Der Anwendungsbereich dieser Methode wurde dahingehend erweitert, daß auf Glashelices aufgebrachtes festes Fluorid zur Eliminierung von β‐Halogensilanen eingesetzt wurde. Dieser Fluoridweg zu gespannten Alkenen ist besonders attraktiv, da die Reaktion bei sehr milden Temperaturen durchgeführt werden kann und die Ausgangsverbindungen leicht zugänglich sind. Dieser Übersichtsartikel beschreibt die Entwicklung des Vakuum‐Gasphasen‐Verfahrens und seine Anwendung bei der Synthese und Charakterisierung von kleinen Cyclo‐ und Bicycloalkenen wie Methylencyclopropen, Spiropentadien, den Bicyclopropenylen, 1,2‐ und 1, 3‐verbrückten Cyclopropenen und anderen einfachen Cyclopropenen.

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7-Dimethylvinylidene-1-methoxybicyclo[4.1.0]heptane and Ethyl 1-Ethoxy-2-methylcyclopropane-3-carboxylate

Cited by 12 publications

References 5 publications

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

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

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

Gasphasensynthese reaktiver Moleküle mit adsorbierten Reagentien

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