Design of Highly Stable Iminophosphoranes as Recyclable Organocatalysts: Application to Asymmetric Chlorinations of Oxindoles.
A new family of tartaric acid derived chiral iminophosphoranes has been developed as highly effective organocatalysts in the asymmetric chlorinations of 3-substituted oxindoles with a high level of enantioselectivity. Importantly, these catalysts are air- and moisture-stable. Recovery of the catalyst after simple chromatographic separation for reuse in the model reaction was achieved; the catalyst can be recycled six times without loss of any enantioselectivity. Several advantages of this catalytic process are high conversion after a very short reaction time at ambient temperature, low catalytic loading, and scale-up to multigram quantities with an excellent enantiomeric excess value of >99%, which meets the enantiomeric purity required for pharmaceutical purposes.
Key Laboratory for Advanced Materials and Institute of Fine Chemicals, East China University of Science and Technology , Meilong Road, 130, Shanghai 200237, P. R. China.|Shanghai-Hong Kong Joint Laboratory in Chemical Synthesis, Shanghai Institute of Organic Chemistry, The Chinese Academy of Sciences , 345 Lingling Road, Shanghai 200032, P. R. China.
Xing
X
Gao
Shanghai-Hong Kong Joint Laboratory in Chemical Synthesis, Shanghai Institute of Organic Chemistry, The Chinese Academy of Sciences , 345 Lingling Road, Shanghai 200032, P. R. China.
Jianwei
J
Han
Key Laboratory for Advanced Materials and Institute of Fine Chemicals, East China University of Science and Technology , Meilong Road, 130, Shanghai 200237, P. R. China.
Limin
L
Wang