Donor-Stabilized Phosphenium Adducts as New Efficient and Immobilizing Ligands in Palladium-Catalyzed Alkynylation and Platinum-Catalyzed Hydrogenation in Ionic Liquids
were tested in palladium‐catalyzed aryl alkynylation and in the platinum‐catalyzed selective hydrogenation of chloronitrobenzenes, both in an ionicliquid phase. In CC bond cross‐coupling we observed that the increase of the π‐acceptor character in ligand 3d, due to the introduction of an additional electron‐withdrawing group, provides a very efficient catalyst in the alkynylation reaction of aryl bromides
描述了通过将溴代呋喃基膦加到1,3-二甲基咪唑-2-羧酸酯1中来直接合成新的供体稳定的d配体3d。所获得的配体表现出非常强的π受体特性,与亚磷酸三苯酯[P(OPh)3 ]或三卤代膦的π受体特性相当,其三羰基镍配合物的v CO(A 1)在2087 cm -1。在离子液相中,在钯催化的芳基炔基化反应和铂催化的氯硝基苯选择性加氢反应中测试了该配体以及从氯二苯膦获得的相关3a。在CC键交叉耦合我们观察到,由于引入了另一个吸电子基团,配体3d中π受体特性的增加为芳基溴化物与苯乙炔的炔基化反应(包括失活的)提供了非常有效的催化剂。 4-溴茴香醚或位阻2-溴萘。由于配体对离子相中质子化的敏感性,催化活性随再循环而降低。相反,通过铂催化的间氯硝基苯加氢,可以在非酸性介质中实现金属/配体系统的多次循环。通过使用氯化铂(II)与3a [反式-PtCl 2的配合物]获得的催化结果(3a)2 ]与非离子相关的反