Inherently Chiral Calixarenes from Catalytic Enantioselective Transannular Arene-Arene Cross-Coupling Reaction



Under the catalysis of PdBr2 and a chiral phosphoramidite ligand derived from R-3,3'-bis(trifluoromethyl)-[1,1'-binaphthalene]-2,2'-diol, the upper-rim mono (2-bromoaroyl)-substituted calix[4]arene derivatives underwent facile enantioselective desymmetrization reaction to afford 9H-fluorene-embedded inherently chiral cyclophanes in good yields with ee up to 94%. The transannular arene-arene cross coupling reaction proceeded most probably through an oxidation addition of Caryl-Br bond to ligated palladium catalyst, an unusual long range 1,5-palladium migration fol-lowed by the intramolecular arylation sequence. Because of the macrocyclic strain, the newly formed 9H-fuorene segment adopts curved structure, rendering highly rigid inherently chiral macrocycles unique chiroptical property.


Supplementary material

Supporting information
supporting information containing experimental procedures and characterization data, copies of 1H and 13C NMR spectra.Photophysical and chiroptical prop-erties.