Asymmetric Epoxidation of cis/trans‐β‐Methylstyrene Catalysed by Immobilised Mn(Salen) with Different Linkages: Heterogenisation of Homogeneous Asymmetric Catalysis. Issue 25 (23rd May 2014)

• Record Type: Journal Article
• Authors: Zhang, Haidong; Zou, Yu; Wang, Yi‐Meng; Shen, Yu; Zheng, Xuxu
• Is Part Of: Chemistry. Volume 20:Issue 25(2014)
• Page Start: 7830
• Page End: 7841
• Publication Date: 2014-05-23
• Subjects: asymmetric catalysis -- epoxidation -- heterogeneous catalysis -- immobilization -- supported catalysis -- surface chemistry; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201402136
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: Immobilised Mn(salen) catalysts with two different linkages were studied in the asymmetric epoxidation of cis / trans ‐β‐methylstyrene using NaClO as oxidant. The immobilised Mn(salen) complexes inside nanopores can lead to different catalytic behaviour compared with that of homogeneous Jacobsen catalyst. The rigidity of the linkage was found to be a key factor affecting the catalytic performance of immobilised catalysts. The immobilised catalyst with a rigid linkage exhibited comparable chemical selectivity, enantioselectivity and cis / trans ratio of product formation to that obtained with homogeneous Jacobsen catalysts. In contrast, the immobilised catalyst with a flexible linkage gave remarkably lower chemical selectivity, enantioselectivity and inverted cis / trans ratio compared with the results obtained with the homogeneous Jacobsen catalyst and the immobilised catalyst with rigid linkage. Thus, for immobilised Mn(salen) catalysts, a rigid linkage connecting active centres to the support is essential to obtain activity and enantioselectivity as high as those obtained in homogeneous systems. Abstract : Getting it fixed : For immobilised Mn(salen) catalysts, a rigid linkage connecting active centres to a support surface is essential to obtain activity and enantioselectivity as high as those obtained in homogeneous systems (see scheme).