Complexes of PdCl2 with chiral oximes of α-(o-anisidino)caranone and α-(o-anisidino)pinanone: synthesis and crystal structures

Synthesis and crystal structures of palladium complexes based on α-amino-oximes derived from (R)-limonene and their application in allylic alkylation of 1,3-dioxo compounds

“…Concerning the 13 C NMR spectra, a similar behaviour is observed around the carbon atoms linked to the N atoms (δ Cq-NOH 164.79 to 171.37 ppm and δ Cq-NH 56.66 to 73.16 ppm from the free ligand to the complex). These values are in total agreement with data collected for L 2 PdCl 2 complexes (L = α-(o-anisidino)caranone and α-(oanisidino)pinanone) [10]. In the case of the ligand L3 and the corresponding complex C3, as described by Royo [19], similar observations could be made: the resonance of the proton of the N-OH shifted from 9.30 ppm in the ligand to 8.62 ppm for the complex.…”

“…Unexpectedly, analysis of the 1 H NMR spectrum of the complex C2 showed two broad signals at δ 9.96 and 9.80 ppm assigned to the OH protons of two diastereoisomers C2 and C 2 present in solution. Kokina observed such results with complexes of PdCl 2 coordinated by amino-oximes ligand issued from carene [10]. He proposed that the two diastereoisomers differ by the configuration of the N atom of the NH group.…”

“…In that context, the family of natural terpenes is a convenient source to produce ligands [7,8]. Among the large variety of ligands issued from terpenes, α-amino-oximes ligands have been synthesized and used with different metals [9] such as Pd [10], Zn and Pt [11], Cu [12], Co [13], or Ni [14] in several fields, from biochemistry and pharmacology applications [15] to organometallic catalysis and asymmetric synthesis. As an example, they have already been applied in catalytic reactions such as homocoupling of amines [16] and epoxidation of olefins [17].…”