Molecularly enlarged S,S-BnTsDPEN ligands for iron-catalyzed asymmetric olefin epoxidation reactions using hydrogen peroxide

V. Yazerski, A. Orue, T. Evers, H. Kleijn, R.J.M. Klein Gebbink

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

A convenient approach for the anchoring of S,S-BnTsDPEN ligands (S,S-N-tosyl-1,2-diphenylethylenediamine) to branched carbosilane scaffolds was investigated. It is based on a high-yielding reductive amination reaction between commercially available S,S-TsDPEN and readily accessible carbosilanes furnished with benzaldehyde terminal fragments. These molecularly enlarged ligands, bearing four S,S-BnTsDPEN units, and their simplified monomeric and “dimeric” analogues were evaluated in iron(III)-catalyzed asymmetric trans-stilbene epoxidation reactions using hydrogen peroxide as an environmentally benign oxidant. The catalytic investigations showed a large degree of variation in the activity and stereoselectivity of the series of DPEN catalysts. In combination with ESI-MS investigations, these data revealed an important role of the ligand orientation in determining the overall activity of the catalyst system. Accordingly, a suitable design of the molecularly enlarged ligands resulted in fully retained activity and selectivity in catalysis. Finally, a number of strategies for the recovery and reuse of the best performing carbosilane-tethered DPEN ligands were explored.
Original languageEnglish
Pages (from-to)2810-2818
Number of pages3
JournalCatalysis Science & Technology
Volume3
Issue number10
DOIs
Publication statusPublished - 2013

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