A new enantiopure d-camphor-derived palladacycle

• d-Camphor O-methyloxime was obtained as a 92:8 mixture of E and Z isomers.
• Reaction of d-camphor O-methyloxime with Na2PdCl4 afforded a coordination complex.
• d-Camphor O-methyloxime reacted with Pd(OAc)2 to give a cyclopalladated complex.
• The crystal structure of the d-camphor-derived cyclopalladated complex is reported.

d-Camphor O-methyloxime (HL, 1) was prepared as a 92:8 mixture of E and Z isomers in 74% yield from d-camphor, methoxyamine hydrochloride and NaOAc in ethanol. Reaction of oxime 1 with Na2PdCl4 in a 2:1 ratio in MeOH at rt provided the coordination complex PdCl2(HL)2 (2) in 67% yield. Cyclopalladation of oxime 1 using Pd(OAc)2 in acetic acid at 80 °C followed by treatment with LiCl furnished the chloro-bridged dimeric cyclopalladated complex [μ-ClPdL]2, 3, in 66% yield. Compound 3 was converted to the mononuclear PPh3 adduct 4 in 98% yield. The proposed structures of new complexes 2–4 were confirmed by 1H, 13C{1H}, DEPT, and 2D NMR spectra. X-ray crystal study of complex 3 revealed the anti geometry of two cyclopalladated ligands as well as the presence of the (sp3)C–Pd bond.

Direct cyclopalladation of readily available d-camphor O-methyloxime with Pd(OAc)2 in acetic acid at 80 °C followed by treatment with LiCl afforded a new chiral complex in a good yield. X-ray crystal structure of the complex revealed its dimeric structure, the anti geometry of two cyclopalladated ligands and the presence of the (sp3)C–Pd bond.Figure optionsDownload as PowerPoint slide