Design of Highly Stable Iminophosphoranes as Recyclable Organocatalysts: Application to Asymmetric Chlorinations of Oxindoles
作者:Xing Gao、Jianwei Han、Limin Wang
DOI:10.1021/acs.orglett.5b02323
日期:2015.9.18
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.
Axially chiral BINIM and Ni(II)-catalyzed asymmetric chlorination of 3-substituted oxindoles
作者:De Wang、Jia-Jun Jiang、Rui Zhang、Min Shi
DOI:10.1016/j.tetasy.2011.06.021
日期:2011.5
Axially chiral BINIM-Ni(II) complexes are effective catalysts in the asymmetric chlorination of 3-substituted oxindoles and give the corresponding chlorinated adducts in good yields and up to 88% ee. (C) 2011 Elsevier Ltd. All rights reserved.