Regiochemistry of the ring expansion of unsymmetrically substituted ketones involving β-hydroxyalkylselenides
作者:A. Krief、J.L. Laboureur
DOI:10.1016/s0040-4039(01)81038-8
日期:1987.1
β-hydroxyalkylselenides derivedfrom unsymmetrically substituted ketones have been rearranged to substituted ketones in the presence of soft electrophiles such as silver tetrafluoraborate or dichlorocarbenes. Although the migration of the more substituted carbon often prevails, subtle variations have been observed depending upon the structure of the starting material and the experimental conditions
The results reported seem to indicate, that in the presence o: a nucleophilic base intramolecularalkylation is the normal reaction mode of tosyloxymethylcyclanones of type 14 and that the fragmentation reaction of five-membered compounds is the exception, probably because of the high steric energy of the alkylation transition states, e.g. of type E.
Aldol-type condensation vs. vinyl selenide formation from selenoacetals
作者:K. M. Nsunda、L. Hevesi
DOI:10.1039/c39870001518
日期:——
Rapid addition of a tertiary amine to tin(IV) chloride–selenoacetal mixtures leads to the corresponding vinylselenides in good yield, whereas slow addition of the amine base gives aldol condensation products.
Connective (C–C) route to hindered epoxides and olefins from hindered ketones
作者:Deniel Labar、Alain Krief
DOI:10.1039/c39820000564
日期:——
Hinderedketones have been transformed into hinderedepoxides (5) and olefins (6) with the concomitant formation of new carbon–carbon bonds using β-hydroxyselenides as key intermediates; the unusual reactivity of such crowded molecules is reported.