A new route to achiral and chiral 1,2-bis(phosphino)ethanes, 1-arsino-2-phosphinoethanes, and 1,3-bis(phosphino)propanes and the molecular structure and catalytic activity of some rhodium(i) complexes derived thereof Dedicated to Professor Wolfdieter A. Schenk, a respected colleague and creative scientist, on the occasion of his 60th birthday.
作者:Guido Fries、Justin Wolf、Kerstin Ilg、Bernhard Walfort、Dietmar Stalke、Helmut Werner
DOI:10.1039/b401585a
日期:——
A series of unsymmetrical 1,2-bis(phosphino)ethanes R2PCH2CH2PR′2
(2a–d) and 1-arsino-2-phosphinoethanes R2AsCH2CH2PR′2
(3a–c) mainly with bulky substituents R and R′ were prepared from the cyclic sulfate 1 by stepwise cleavage of the carbon–oxygen bonds by LiPR2 and LiPR′2 or LiAsR2 and LiPR′2, respectively. Analogously, racemic mixtures of R2PCH2CH(Me)PPh2
(R =
iPr 5a, Cy 5b) as well as the enantiomers (R)-5a, (R)-5b and (R)-tBu2PCH2CH(Me)PPh2
(R)-5c were obtained from the corresponding unsymmetrical cyclic sulfates 4 and (S)-4. On a similar route, the racemates of the 1,3-bis(phosphino)propanes R2PCH2CH2CH(Me)PPh2
(R =
iPr 7, tBu 8), optically pure (R)-8 and (S,S)-iPr2PCH(Me)CH2CH(Me)PPh2
(S,S)-10 were prepared. The reaction of [RhCl(η4-C8H12)}2] with chelating ligands L–L, where L–L is R2PCH2P(men)2
(R =
iPr, Ph; men =
(1S,2R,5S)-menthyl), Cy2AsCH2P(men)2, or (R)-5a, (R)-5b, (R)-5c, (R)-8 and (S,S)-10, in the presence of AgPF6, gave the complexes [Rh(η4-C8H12)(L–L)]PF6
(12a–h) which were used as pre-catalysts in the hydrogenation of the methyl ester of α-acetamidocinnamic acid (ACM). Depending on L–L, the solvent, the temperature and the pressure of H2, optical yields of up to 69% ee were achieved. For two of the rhodium complexes, 12c and 12d, the molecular structures were determined by X-ray crystallography.
一系列不对称的 1、通过 LiPR2 和 LiPR′2 或 LiAsR2 和 LiPR′2逐步裂解碳氧键,从环状硫酸盐 1 制备出了主要带有大取代基 R 和 R′的 1、2-双(膦)乙烷 R2PCH2CH2PR′2 (2a-d)和 1-胂-2-膦乙烷 R2AsCH2CH2PR′2 (3a-c)。同样,从相应的不对称环状硫酸盐 4 和 (S)-4 中得到了 R2PCH2CH(Me)PPh2 的外消旋混合物(R = iPr 5a、Cy 5b)以及对映体 (R)-5a、(R)-5b 和 (R)-tBu2PCH2CH(Me)PPh2 (R)-5c。按照类似的路线,制备了 1,3-双(膦)丙烷 R2PCH2CH2CH(Me)PPh2(R = iPr 7,tBu 8)的外消旋体、光学纯 (R)-8 和 (S,S)-iPr2PCH(Me)CH2CH(Me)PPh2 (S,S)-10。[RhCl(η4-C8H12)}2]与螯合配体 L-L 反应,其中 L-L 是 R2PCH2P(men)2 (R = iPr,Ph;men=(1S,2R,5S)-menthyl)、Cy2AsCH2P(men)2 或 (R)-5a、(R)-5b、(R)-5c、(R)-8 和 (S,S)-10、得到了[Rh(η4-C8H12)(L-L)]PF6(12a-h)复合物,这些复合物被用作 α-乙酰胺肉桂酸(ACM)甲酯氢化反应的前催化剂。根据 L-L、溶剂、温度和 H2 压力的不同,光学产率可达 69% ee。通过 X 射线晶体学,确定了 12c 和 12d 这两种铑络合物的分子结构。