Highly enantioselective epoxidation of olefins by H ₂ O ₂ catalyzed by a non-heme Fe(ii) catalyst of a chiral tetradentate ligand

Summary, in English

The chiral tetradentate N4-donor ligand, 1-methyl-2-({(S)-2-[(S)-1-(1-methylbenzimidazol-2-yl methyl)pyrrolidin-2-yl]pyrrolidin-1-yl}methyl) benzimidazole (S,S-
^PDBz
L), based on a chiral dipyrrolidine backbone, has been synthesized and its corresponding Fe(ii) complex has been prepared and characterized. The X-ray structure of the complex reveals that the Fe(ii) ion is in a distorted octahedral coordination environment with two cis-oriented coordination sites occupied by (labile) triflate anions. The ability of the iron complex to catalyze asymmetric epoxidation reactions of olefins with H
₂
O
₂
was investigated, using 2-cyclohexen-1-one, 2-cyclopenten-1-one, cis-β-methylstyrene, isophorone, chalcones and tetralones as substrates. Different carboxylic acids were used as additives to enhance yields and enantioselectivities, and 2-ethylhexanoic acid was found to give the best results. The catalysis results indicate that the Fe(ii) complex is capable of effecting comparatively high enantioselectivities (>80%) in the epoxidation reactions.

• Author: Mainak Mitra; Olaf Cusso; Satish S. Bhat; Mingzhe Sun; Marco Cianfanelli; Miquel Costas; Ebbe Nordlander
• Department/s: Chemical Physics; Centre for Analysis and Synthesis
• Publishing year: 2019
• Language: English
• Pages: 6123-6131
• Publication/Series: Dalton Transactions
• Volume: 48
• Issue: 18
• Links: http://dx.doi.org/10.1039/c8dt04449j
• Document type: Journal article
• Publisher: Royal Society of Chemistry
• Topic: Chemical Sciences
• Status: Published
• ISBN/ISSN/Other: ISSN: 1477-9226