Chiral Wide-Bite-Angle Diphosphine Ligands: Synthesis, Coordination Chemistry, and Application in Pd-Catalyzed Allylic Alkylation
Chiral Wide-Bite-Angle Diphosphine Ligands: Synthesis, Coordination Chemistry, and Application in Pd-Catalyzed Allylic Alkylation
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手性宽咬角二膦配体：合成、配位化学及其在 Pd 催化烯丙基烷基化中的应用
DOI：
10.1021/om5008055
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发表时间：
2015
期刊：
影响因子：
2.8
通讯作者：
Czauderna C
中科院分区：
文献类型：
--
作者：
Czauderna C
合成了一系列含酯基和醚基二苯醚骨架的双膦配体。在引入膦之前，通过简单的四步合成方案在相对于二苯基膦基团的邻位引入羧酸或醚助剂。通过红外光谱和~（31）P核磁共振谱分别测定了Ni（CO）_2（PP）分子的羰基伸缩频率和硒化膦衍生物的磷-硒偶合常数，研究了这些主链修饰的DPEPhos配体的电子性质.此外，双（羰基）镍（0）物种与配体之一的X-射线结构的报告。用多核核磁共振（NMR）对[Pd（η3-allyl）（PP）]配合物进行了表征，并将其应用于丙二酸二甲酯与1，3-二苯基-2-丙烯基乙酸酯和环己-2-烯基乙酸酯的不对称烯丙基烷基化反应，考察了其催化活性.的对映体选择性（范围从3至70%）被发现取决于大小的手性助剂内引入的二苯醚骨架和其接近的磷供体基团，因此活性金属中心。
A series of diphosphine ligands bearing ester- and ether-modified diphenylether backbones have been prepared. The introduction of carboxylic acid or ether auxiliaries in theortho-positions relative to the diphenylphosphine groups was achieved via straightforward four-step synthetic protocols, prior to introduction of the phosphines. The electronic properties of these backbone-modified DPEPhos ligands were evaluated by probing the relevant carbonyl stretching frequencies (νCO) of Ni(CO)2(PP) species (PP = diphosphine) using IR spectroscopy and by determining the phosphorus–selenium coupling constantJSe–Pof phosphine selenide derivatives using31P{1H} NMR spectroscopy. Also, the X-ray structure for the bis(carbonyl)nickel(0) species with one of the ligands is reported. The [Pd(η3-allyl)(PP)] complexes were characterized by multinuclear NMR spectroscopy and applied in the asymmetric allylic alkylation of l,3-diphenyl-2-propenyl acetate and cyclohex-2-enyl acetate with dimethyl malonate in order to benchmark their catalytic potential. The enantioselectivity (ranging from 3 to 70%) was found to depend on the size of the chiral auxiliary introduced within the diphenyl ether backbone and its proximity to the phosphorus donor groups and hence to the active metal center.