Tetrahedron ( IF 2.233 ) Pub Date : 2019-11-18 , DOI: 10.1016/j.tet.2019.130780 Anne-Marie Carroll,Mary McCarthy,Patrick M. Lacey,Cormac P. Saunders,David J. Connolly,Annette Farrell,Balaji V. Rokade,Richard Goddard,Peter Fristrup,Per-Ola Norrby,Patrick J. Guiry
The application of palladium complexes of a modular series of axially chiral phosphinamine ligands, the Quinazolinaps, to the enantioselective alkylation of 1,3-diphenyl-2-propenyl acetate with dimethyl malonate and methyl dimethyl malonate is described. Complete conversions and enantiomeric excesses of up to 91% were obtained. To elucidate the solution structure of these complexes and their dynamic behaviour, 2D COSY and NOESY NMR experiments were carried out. An X-ray crystal structure of a palladacycle derived from 2-phenylQuinazolinap which possesses two Pd3Cl5 units is shown. Computational studies were also undertaken to allow qualitative predictions of diastereomeric ratios. The observed enantioselectivity was then rationalised in terms of combined spectroscopic and theoretical data. The catalytic results obtained are best interpreted by the reaction proceeding with nucleophilic attack on the allyl trans to the phosphorus donor atom of the major diastereomeric intermediate.
描述了模块化系列的轴向手性次膦胺配体喹唑啉类的钯配合物在1，3-二苯基-2-丙烯基乙酸乙酸酯与丙二酸二甲酯和丙二酸二甲酯的对映选择性烷基化中的应用。获得完全转化和对映体过量至多91％。为了阐明这些络合物的溶液结构及其动态行为，进行了2D COZY和NOESY NMR实验。衍生自具有两个Pd 3 Cl 5的2-苯基喹唑啉酮的Palladacycle的X射线晶体结构显示了单位。还进行了计算研究以对非对映异构体比率进行定性预测。然后根据光谱数据和理论数据对观察到的对映选择性进行合理化处理。通过对烯丙基反式转化为主要非对映异构中间体的磷供体原子进行亲核攻击，可以最好地解释所获得的催化结果。