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Synfacts 2015; 11(1): 0109
DOI: 10.1055/s-0034-1379724
DOI: 10.1055/s-0034-1379724
Polymer-Supported Synthesis
Asymmetric α-Benzylation with Cinchonidium Salt Based Polymers
Further Information
Publication History
Publication Date:
15 December 2014 (online)
Significance
Chiral polymers 3 and 5 were prepared from cinchonidine dimers 1 (eqs. 1 and 2). All polymers showed high catalytic performance in the asymmetric α-benzylation of N-diphenylmethylene glycine tert-butyl ester with benzyl bromide (eq. 3, 77–95% yield, 81–92% ee).
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Comment
The polymer catalysts were recovered by filtration and reused without loss of catalytic performance. The reaction also took place at –40 °C to give the product with improved ee (with 3bc: 24 h, 83% yield, 95% ee). The catalytic activity and the stereoselectivity observed with the polymeric catalysts 3 and 5 were comparable to those obtained with the homogeneous catalysts 1.
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