58712-11-1Relevant academic research and scientific papers
Asymmetric synthesis of tetracyclic benzo[a]quinolizidine targets
Allin, Steven M.,Gaskell, Sean N.,Elsegood, Mark R. J.,Martin, William P.
, p. 6448 - 6451 (2008/12/21)
(Chemical Equation Presented) We report a novel, facile, and asymmetric approach for the synthesis of polycyclic benzo[a]quinolizidine targets. In the formation of more functionalized derivatives, we have observed the generation of an iminium ether salt intermediate, formed during an unprecedented retro-Diels-Alder/N-acyliminium cyclization cascade. The iminium ether intermediate was isolated in good yield, characterized by X-ray crystallography, and subsequently applied as a synthetic building block.
The mechanism of the photochemical cycloaddition reaction between 2-cyclopentenone and polar alkenes: Trapping of triplet 1,4-biradical intermediates with hydrogen selenide
Andrew, David,Hastings, David J.,Weedon, Alan C.
, p. 10870 - 10882 (2007/10/02)
The regiochemistry of the photochemical cycloaddition reaction between 2-cyclopentenone and the polar alkenes 1,1-difluoroethene and methyl acrylate has been investigated. With 1,1-difluoroethene the major cycloaddition product is a cyclobutane adduct possessing head-to-tail regiochemistry; with methyl acrylate the reaction is non-regioselective and a 46.5:53.5 ratio of head-to-head and head-to-tail cyclobutane regioisomers is obtained. These regiochemical outcomes are not those predicted by the Corey - de Mayo mechanism conventionally used to describe the enone - alkene photocycloaddition reaction. The triplet 1,4-biradicals implicated as intermediates in the photocycloaddition reaction between 2-cyclopentenone and the polar alkenes methyl acrylate and ethyl vinyl ether have been trapped quantitatively using hydrogen selenide as a hydrogen atom donor. The structures of the trapped products have been determined and hence the structures of their biradical precursors have been inferred. The yields of the trapped biradicals indicate that in both reactions the product distribution is controlled by the extent to which each of the isomeric biradical intermediates closes to products in competition with fragmentation to its ground state precursors. The product distribution does not reflect the relative rates of formation (and hence the relative amounts) of the isomeric biradical intermediates formed in each reaction. This conclusion is inconsistent with the long held idea that an oriented exciplex intermediate controls the reaction regiochemistry by favoring the formation of some biradicals over others. The structures of the biradical intermediates also reveal that both the 2-position and the 3-position of the enone are involved in forming the first bond to the alkene; with ethyl vinyl ether this bond is to the less substituted end of the alkene exclusively, while with methyl acrylate no selectivity in the site of initial bonding is observed.
Process for preparing cyclopent-2-en-1-one derivatives
-
, (2008/06/13)
A process for preparing cyclopent-2-en-1-one derivatives of the formula STR1 wherein R1 is a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group, and R2 is a hydrogen atom or a substituent which is not substantially brominated under the treating conditions, which comprises treating a cyclopentanone derivative of the formula STR2 wherein R1 and R2 are the same as defined above, with pyridinium hydrobromide perbromide.
