Trinuclear Non-Heme Iron Complexes Based on 4-Substituted 2,6-Diacylpyridine Ligands as Catalysts in Aerobic Allylic Oxidations
✍ Scribed by Volker Rabe; Wolfgang Frey; Angelika Baro; Sabine Laschat
- Publisher
- John Wiley and Sons
- Year
- 2012
- Tongue
- German
- Weight
- 261 KB
- Volume
- 95
- Category
- Article
- ISSN
- 0018-019X
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✦ Synopsis
Abstract
Taking the regio‐ and chemoselectivities of our iron complex precursors with pyridine core in aerobic oxidations into account, we envisioned a more effective influence on catalytic properties by the introduction of different substituents in 4‐position of the pyridine moiety. The synthesis of these novel 4‐substituted (pyridine‐2,6‐diyl)dipropanoic acids 4 is described. Analogously to the unsubstituted derivative, ligands 4 reacted with Fe(ClO~4~)~3~ to form trinuclear Fe~3~(μ~3~‐O) complexes 3, which were tested in the aerobic Gif‐type oxidation of α‐pinene to myrtenol, verbenone, myrtenal, and pinene oxide. The electronic nature of the substituents was found to slightly effect the ratio of allylic oxidation/epoxidation, whereas its influence on the oxidation preference of secondary to primary CH bonds is negligible as compared to the unsubstituted complex.