Additive Effects of Amines on Asymmetric Hydrogenation of Quinoxalines Catalyzed by Chiral Iridium Complexes
作者:Takuto Nagano、Atsuhiro Iimuro、Rino Schwenk、Takashi Ohshima、Yusuke Kita、Antonio Togni、Kazushi Mashima
DOI:10.1002/chem.201201366
日期:2012.9.10
The additive effects of amines were realized in the asymmetric hydrogenation of 2‐phenylquinoxaline, and its derivatives, catalyzed by chiral cationic dinuclear triply halide‐bridged iridium complexes [Ir(H)[diphosphine]}2(μ‐X)3]X (diphosphine=(S)‐2,2′‐bis(diphenylphosphino)‐1,1′‐binaphthyl [(S)‐BINAP], (S)‐5,5′‐bis(diphenylphosphino)‐4,4′‐bi‐1,3‐benzodioxole [(S)‐SEGPHOS], (S)‐5,5′‐bis(diphenylphosphino)‐2
在手性阳离子双核三卤化物桥联铱络合物[Ir(H)[diphosphine]} 2(μX)3 ] X的催化下,2-苯基喹喔啉及其衍生物的不对称氢化实现了胺的加合作用。(二膦=(S)‐2,2′‐双(二苯基膦基)‐1,1′‐联萘基[(S ‐‐BINAP ],(S)‐5,5′‐双(二苯基膦基)‐4,4′‐ bi-1,3-苯并二恶唑[(S)-SEGPHOS],(S)-5,5'-双(二苯基膦基)-2,2,2',2'-四氟-4,4'-bi-1, 3-苯并二恶唑[(S)-DIFLUORPHOS]; X = Cl,Br,I)生成相应的2-芳基-1,2,3,4-四氢喹喔啉。通过在N-甲基-对-茴香胺(MPA)存在下铱络合物的溶液动力学研究来研究胺的加成作用,该溶液被确定为实现(S)-2高对映选择性的最佳胺添加剂-苯基-1,2,3,4-四氢喹喔啉,并通过标记实验揭示了一个合理的机理,该机理包括两个周期。一个催