Asymmetric Cyclopropanation with Immobilized Ru(II)-Salen-Py2

C. S. Gill; K. Venkatasubbaiah; C. W. Jones

doi:10.1055/s-0029-1217653

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Synfacts 2009(9): 1050-1050
DOI: 10.1055/s-0029-1217653

Polymer-Supported Synthesis

Asymmetric Cyclopropanation with Immobilized Ru(II)-Salen-Py₂

Contributor(s): Yasuhiro Uozumi, Yoichi M. A. Yamada, Toshihiro Watanabe
C. S. Gill, K. Venkatasubbaiah, C. W. Jones*
Georgia Institute of Technology, Atlanta, USA

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Publication History

Publication Date:
21 August 2009 (online)

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Significance

Polymer-supported ruthenium(II)-salen-py₂ catalysts 2a and 2b were prepared by polymerization of styryl-salen monomers (1a and 1b) and divinylbenzene, followed by treatment with n-BuLi and subsequent complexation with [Ru(Cy)₂Cl₂]₂ in the presence of pyridine. Asymmetric cyclopropanation of styrene (4) with diazo-acetate (5) with 2a gave cyclopropanes in 97% yield with good selectivity (trans/cis ratio 9.1, trans 90% ee, cis 82% ee). Catalyst 2b with a glycol linker provided higher selectivity of the products than 2a [97% yield, trans/cis ratio 10.7, trans 94% ee, cis 90% ee)].