Isomerisations acides de cyclobutanones tetrasubstituees

Bourelle-Wargnier, F.; Jeanne-Carlier, R.

doi:10.1016/0040-4020(76)80113-5

Cited by 11 publications

(1 citation statement)

References 23 publications

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“…mol-' et la contribution d'environ 13 k cal.mol-' du groupe ~i n y l e '~) a l'abaissement de l'energie d'activation se combinent partiellement pour faciliter thermiquement cette reaction et la rendre attractive en ~ynthese'~). Actuellement, le debat sur le caractere concert6 du rearrangement reste ouvert malgre les travaux tres nombreux consacres au mecanisme de cette isomerisation") ( ; l'utilisation de sels de sulfonium derives du tetrahydrothiophene permet d'augmenter le rendement en epoxydes (20). Toutes ces methodes fournissent des epoxydes de configuration E sur la double liaison.…”

Section: Le Rearrangement Thermique Du Vinylcyclopropane (X=ch2) En Cunclassified

Agrandissement Thermique de Cycles à Trois Chaînons Vinyliques

Chuche

1981

Bulletin des Soc Chimique

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Section: Le Rearrangement Thermique Du Vinylcyclopropane (X=ch2) En Cunclassified

Agrandissement Thermique de Cycles à Trois Chaînons Vinyliques

Chuche

1981

Bulletin des Soc Chimique

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Halogenierte Cyclobutanone als variationsreiche Vorläufer von Pyrethroiden: Synthesen durch [2+2]‐Cycloadditionen von Haloketenen an 1,1‐disubstituierte Äthylene

Martin

Greuter

Belluš

1981

Helvetica Chimica Acta

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2 + 21-Cycloaddition reactions of the new chloro-(2,2,2-trichloroethyl)ketene (9) with various 1,l-disubstituted ethylenes as well as [2 + 21-cycloadditions of highly halogenated ketenes of type 32 are described. The halogenated cyclobutanones thus obtained represent valuable intermediates in a new synthesis of insecticidal pyrethroids (Scheme 1). Ketene 9, prepared in situ from readily available precursors, parallels, if not exceeds, dichloroketene in its reactivity. With isobutene, the cyclobutanone 10 (a precursor for cis-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid) is obtained in 70% yield. The reaction of 9 with propene is stereospecific and leads to cis-17, exclusively. This result may be explained in terms of the energetically most favourable approach of the reacting molecules in a [,2, + .2,] process.

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Acid‐Catalysed Rearrangements of α‐Vinylcyclobutanones

Jackson

Rey

Dreiding

1985

Helvetica Chimica Acta

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The BF, . Et,O-and the CH,SO,H-catalysed rearrangements of 10 a -vinylcyclobutanones have been examined. With little acid, the j?,j?-dialkyl derivatives 1 were transformed into linear dienones 2 and 3; with more acid, they were converted into cyclopentenones 4 by Nazarou cyclisation of initially formed 2/3. The j?-monoalkyl (including the P,y-dialkyl) derivatives 7 rearranged only with a high acid concentration to afford the cyclopentenones 8 by 1,2-acyl migration. In the case of 7a, the cyclopentenone 8a was accompanied by the unexpected constitutional isomer 98, which is explained by a reversible interconversion of the cyclobutanone 7a with its isomer 19 via a cyclopropane intermediate like 18. In the case of the j?,j?-dialkyl derivative 5, which contains an a-isobutenyl (instead of an a-vinyl) group, the acid-catalysed rearrangement product was the bicyclo[3.1 .O]hexanone derivative 6.

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Isomerisations acides de cyclobutanones tetrasubstituees

Cited by 11 publications

References 23 publications

Agrandissement Thermique de Cycles à Trois Chaînons Vinyliques

Agrandissement Thermique de Cycles à Trois Chaînons Vinyliques

Halogenierte Cyclobutanone als variationsreiche Vorläufer von Pyrethroiden: Synthesen durch [2+2]‐Cycloadditionen von Haloketenen an 1,1‐disubstituierte Äthylene

Acid‐Catalysed Rearrangements of α‐Vinylcyclobutanones

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