Improved methods for the preparation of methylene-bridged diphosphine ligands are described. Both enantiomers of the key intermediate tert-butylmethylphosphine–borane were prepared via resolution or by the conversion of one enantiomer into the opposite enantiomer. The precursor borane complexes of bis(tert-butylmethylphosphino)methane (t-Bu-MiniPHOS), bis((1,1,3,3-tetramethylbutyl)methylphosphino)methane
Utilization of optically active secondary phosphine–boranes: synthesis of P-chiral diphosphines and their enantioinduction ability in rhodium-catalyzed asymmetric hydrogenation
作者:Tsuneo Imamoto、Yumi Horiuchi、Eri Hamanishi、Satoshi Takeshita、Ken Tamura、Masashi Sugiya、Kazuhiro Yoshida
DOI:10.1016/j.tet.2015.05.088
日期:2015.9
have been used for the synthesis of P-chiral diphosphines and/or their borane complexes. The enantiopure borane complex of 1,2-bis(tert-butylmethylphosphino)ethane (t-Bu-BisP∗) was prepared in high yield from the secondary phosphine–borane and 1,2-dichloroethane. A mono-chelated Rh-complex of t-Bu-MiniPHOS was prepared and its catalytic activity was examined in the asymmetric hydrogenation of some representative