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Inherently chiral calixarenes by a catalytic enantioselective desymmetrizing cross-dehydrogenative coupling
Ist Teil von
Chemical science (Cambridge), 2023-01, Vol.14 (4), p.827-832
Ort / Verlag
England: Royal Society of Chemistry
Erscheinungsjahr
2023
Quelle
EZB Electronic Journals Library
Beschreibungen/Notizen
Under the catalysis of PdBr
2
and a chiral phosphoramidite ligand, the upper-rim mono (2-bromoaroyl)-substituted calix[4]arene derivatives underwent a facile enantioselective desymmetrization reaction to afford 9
H
-fluorene-embedded inherently chiral calixarenes in good yields with excellent enantioselectivities. The transannular dehydrogenative arene-arene coupling reaction proceeded most probably through an oxidative addition of the C
aryl
-Br bond to a ligated palladium catalyst followed by a sequence of an enantioselective 1,5-palladium migration and an intramolecular C-H arylation sequence. This new family of inherently chiral calixarenes possesses unique chiroptical properties thanks to their highly rigid structure induced by the 9
H
-fluorene segment.
Reported here is the catalytic enantioselective desymmetrization of calixarene skeletons for the construction of inherently chiral calixarenes through a transannular arene-arene dehydrogenative coupling reaction.