Catalytic transfer hydrogenation of ketones by the use of ruthenium complexes incorporating the new tridentate ligand, bis(2-oxazolin-2-ylmethyl)phenylphosphine
作者:Pierre Braunstein、Michael D. Fryzuk、Frédéric Naud、Steven J. Rettig
DOI:10.1039/a808170k
日期:——
The new heterofunctional phosphine ligand bis(2-oxazolin-2-ylmethyl)phenylphosphine (N,P,N) has been prepared and has allowed the synthesis of the ruthenium complexes fac-[RuCl2(DMSO)(N,P,N)] 1, fac-[RuCl2(PPh3)(N,P,N)] 2, [RuCl(η6-C6H6)(N,P,N)][O3SCF3] 3 and [Ru(η6-C6H6)(N,P,N)][O3SCF3]2 4. When tridentate, as in 1, 2, and 4, this ligand co-ordinates in a facial-type mode. In complex 3, it acts as a P,N-chelate with a dangling oxazoline ring. The structures of the ligand, 2·CH2Cl2·0.25C6H14 and 3 have been determined by X-ray diffraction. Complexes 1–4 catalyse the transfer hydrogenation reaction between propan-2-ol and ketones. Only small differences in reactivity were observed between 3 and 4, despite the different ligand bonding mode in these complexes. For the best catalyst, 2, yields up to 97% were obtained and turnover frequencies may be as high as 112 000 h–1.
新的杂功能膦配体双(2-噁唑啉-2-基甲基)苯基膦(N,P,N)已经制备完成,并合成了钌配合物 fac-[RuCl2(DMSO)(N、P,N)] 1、fac-[RuCl2(PPh3)(N,P,N)] 2、[RuCl(η6-C6H6)(N,P,N)][O3SCF3] 3 和 [Ru(η6-C6H6)(N,P,N)][O3SCF3]2 4。当配体为三叉配体时,如 1、2 和 4,该配体以面型模式配位。在复合物 3 中,它是一个带有悬挂噁唑啉环的 P,N-螯合物。配体、2-CH2Cl2-0.25C6H14 和 3 的结构已通过 X 射线衍射测定。1-4 号络合物可催化丙-2-醇和酮之间的转移加氢反应。尽管 3 和 4 复合物的配体键合方式不同,但它们的反应活性只有很小的差异。最佳催化剂 2 的产率高达 97%,周转率可高达 112 000 h-1。