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首页> 外文期刊>Organometallics >Endo-effect-driven regioselectivity in the cyclopalladation of (S)-2-tert-butyl-4-phenyl-2-oxazoline
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Endo-effect-driven regioselectivity in the cyclopalladation of (S)-2-tert-butyl-4-phenyl-2-oxazoline

机译：（S）-2-叔丁基-4-苯基-2-恶唑啉环钯中内驱力驱动的区域选择性

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Direct cyclopalladation of (S)-2-tert-butyl-4-phenyl-2-oxazoline using palladium acetate in acetic acid or acetonitrile provided a mixture of two isomeric compounds, the endo A-AcO dimeric complex with a C(sp(3))-Pd bond and the corresponding exo derivative with a C(sp(2))-Pd bond, with the former being the major product. The A-AcO dimeric complexes were converted to the corresponding A-Cl analogues 3 and 4 by treatment with LiCl in acetone; the latter compounds were transformed to the corresponding PPh3 adducts 5 and 6. The NMR data suggested the puckered structure of the endo palladacycle in complexes 3 and 5, the twisted lambda(S) conformation of the oxazoline ring in 3, 4, and 6, and the delta(S) conformation of the heterocycle in complex 5. The X-ray crystal structure of 5 confirmed the delta(S) conformation of the oxazoline ring in the solid state and the twisted conformation of the palladacycle and revealed a P-propeller chiral configuration of the PPh3 ligand. A series of ab initio quantum chemical calculations were performed on two model compounds generated by replacing the PPh3 ligands with NH3 in complexes 5 and 6. The structures and energies of the two model exo and endo isomers were calculated at the RHF, BLYP, and MP2 levels of theory with a 6-31G* basis for the light atoms and LANL2DZ ECP for the palladium and were found to be comparable. Single point coupled cluster calculations, with single double excitations (CCSD), corroborated the results.
机译：使用乙酸钯在乙酸或乙腈中的（S）-2-叔丁基-4-苯基-2-恶唑啉直接环钯反应提供了两种异构体化合物的混合物，即内聚A-AcO二聚体与C（sp（3 ））-Pd键和具有C（sp（2））-Pd键的相应exo衍生物，前者是主要产物。通过在丙酮中用LiCl处理，将A-AcO二聚体复合物转化成相应的A-Cl类似物3和4。后者的化合物被转化为相应的PPh3加合物5和6。NMR数据表明，配合物3和5中内帕拉达环的褶皱结构，3、4和6中恶唑啉环的扭曲lambda（S）构象。和配合物5中杂环的δ（S）构象。5的X射线晶体结构证实了固态的恶唑啉环的δ（S）构象和保拉达环的扭曲构象，并揭示了P-螺旋桨。 PPh3配体的手性构型。对通过在络合物5和6中用NH3取代PPh3配体而生成的两种模型化合物进行了一系列从头算量子化学计算。在RHF，BLYP和MP2上计算了两种模型外向异构体和内向异构体的结构和能量轻原子的理论水平为6-31G *，钯的理论水平为LANL2DZ ECP，发现具有可比性。单点耦合群集计算和单双激励（CCSD）证实了结果。

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