The first P-chirogenic mono-and diphosphine ligands supported on the upper rim of a calix[4]arene moiety were synthesized using the ephedrine methodology. The lithiated calix[4]arene mono-and dianions both react with the oxazaphospholidine−borane, prepared from ephedrine, to afford regio-and stereoselectively the corresponding calix[4]arenyl aminophosphine−boranes, by cleavage of the heterocyclic ring at the P−O bond position. Subsequent reactions with HCl and then organolithium reagent and finally decomplexation with DABCO lead to the corresponding calix[4]arenyl mono-or diphosphines. Both enantiomers of the calix[4]arenyl phosphines were obtained either by using (+)-or (−)-ephedrine or by changing the addition order of the organolithium reagents during the synthesis. The enantiomeric excesses of the phosphines were determined either by HPLC on a chiral column of their borane complexes or by 31 P NMR in the presence of a chiral palladium complex. The absolute configurations of the mono-and diphosphinocalix[4]arenes were assigned by X-ray analysis of their crystalline borane complexes. The P-chirogenic calix[4]arenyl phosphines were tested for asymmetric palladium-catalyzed allylic substitution of (E)-1,3-diphenylprop-2-en-1-yl acetate, by dimethyl malonate or benzylamine. When the bismethylphenylphosphino calix[4]arene was used, the allylic products were obtained with 82% and 79% ee, respectively. In both cases, the use of a diphosphine affords better results than using 2 equivalents of monophosphine. Despite the C 2 symmetry of the P-chirogenic diphosphine calix[4]arene ligand, computer modeling of the corresponding Pd(allyl) complex shows a clear dissymmetry of the LUMO, which is in good agreement with a complexed η 1 -allyl moiety and with the regio-and enantioselectivity of the Pd-catalyzed allylations.

New series of Pd-catalysts based N-heterocyclic carbene ligand PEPPSI-Type, (PEPPSI = Pyridine Enhanced Precatalyst Preparation Stabilization and Initiation) with the general formula [Pd(II)Br2(NHC)(pyridine)]. were synthesized, and fully characterized by spectroscopic...

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