(Hydroxyalkyl)pyridinooxazolines in Palladium-Catalyzed Allylic Substitutions. Conformational Preferences of the Ligand

2-(3‘,4‘-Dihydro-2‘-oxazolyl)-6-(hydroxymethyl)pyridines have been shown by X-ray crystallographic analysis and DFT calculations to exhibit two conformational minima in their complexes with Pd(II) chloride. Theoretical studies of (π-allyl)palladium(II) and (π-olefin)palladium(0) complexes with 2-(3‘,4‘-dihydro-2‘-oxazolyl)-6-(hydroxymethyl)pyridine revealed two minima in each complex. In contrast, in the calculations of the Pd(II) chloride and Pd(II) allyl complexes of 2-(3‘,4‘-dihydro-2‘-oxazolyl)-6-(methoxymethyl)pyridine a single conformational minimum was found. NOE studies of complexes in solution were in agreement with the results obtained by the theoretical studies. The knowledge about the conformational preferences of the palladium complexes with (hydroxyalkyl)pyridinooxazolines and (methoxyalkyl)pyridinooxazolines is used to rationalize the results of palladium-catalyzed allylic alkylations employing the two types of ligands.