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Cyclopropylmethyl-Allylmethyl Systems

Cyclobutyl-Cyclopropylmethyl-Allylmethyl Systems. The long-accepted picture that interconversions amongst the cations in this system take place via a rapid equilibrium of classical structures has recently been criticized by Olah. He has argued, on the basis of n.m.r. evidence, in favour of non-classical a-delocalized structures for primary cyclopropylcarbinyl cations, although recognizing that localized, and even static, structures are involved in secondary and tertiary cases, and especially in the 8,9-dehydro-2-adamantyl series. Hehre and Hiberty have now questioned the (T-delocalized picture of the parent ion presented by Olah, and provide ab [Pg.158]

Evidence for the bisected structure of cyclopropylcarbinyl cations has been provided by solvolysis of deuterium-labelled derivatives. Attempts to determine the stereochemistry of the degenerate rearrangement of cyclohexenyl cations via cyclopropylcarbinyl intermediates have not been successful.  [Pg.158]

Solvolysis of homoallylic tosylates with cyclopropylcarbinyl participation has also been reported.  [Pg.158]

Cyclopropylmethanol derivatives (750 X = COPh, CO Me, CONH2, NOj, or NO) have been synthesized by the silver-ion-assisted acetolysis of a-substituted bromocyclobutanes (749). In the case of (749 X = COPh), the allylcarbinyl acetate (751) was also formed, along with (750). [Pg.158]

Zon and Paquette have examined the synthetic utility of the Ag -promoted ionization of cyclopropylcarbinyl alkyl ethers. The cycloheptene (753) was the main product obtained on heating (752) with silver perchlorate in benzene, and (754) and [Pg.158]


Allylmethyl-Cyclopropylmethyl-Cyclobutyl Systems. A further note of caution has been sounded on the use of coupling constants as criteria for the presence,... [Pg.76]

Allylmethyl-Cyclopropylmethyl-Cyclobutyl Systems. The cyclopropylmethyl cation has been the subject of semi-empirical natural orbital analysis, and the bonding analysis supports the suggestion that there is delocalization of charge throughout the species. MINDO/3 geometries have been obtained for both planar and non-planar homotropylium cation, and the results of the study show the ion to be best represented as an open species and not as a delocalized bicyclo[5,l,0]octadienyl cation, as previously suggested. ... [Pg.79]

Electrophilic ring opening of bicyclo[l. 1.0]butanes generally leads to mixtures of cyclobutyl, cyclopropylmethyl and allylmethyl compounds, among which the first two products dominate.The parent bicyclo[1.1.0]butane (1) is converted into cyclobutanol and cyclo-propanemethanol, without formation of any but-3-en-l-ol, upon treatment with 0.001 N sulfuric acid. Acetolysis of bicyclo[1.1.0]butane affords a mixture of all three acetates. In general, the product ratio is highly dependent on the substitution pattern of the bicyclic system. [Pg.1249]


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