Titanium Salan/Salalen Complexes: The Twofaced Janus of Asymmetric Oxidation Catalysis

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• 作者：Evgenii P. Talsi ; Anna A. Bryliakova and Konstantin P. Bryliakov
• 关键词：asymmetric oxidation ; chirality ; esomeprazole ; hydrogen peroxide ; titanium
• 刊名：The Chemical Record
• 出版年：2016
• 出版时间：April 2016
• 年：2016
• 卷：16
• 期：2
• 页码：924-939
• 全文大小：1100K
• ISSN：1528-0691

文摘

Optically pure chiral epoxides and sulfoxides are ubiquitous building blocks in fine organic synthesis, employed in the pharmaceutical, agrochemical, and cosmetic industries. On the road to chiral epoxides and sulfoxides, efficient and stereoselective transition metal-based catalysts are the most promising guides. Among transition metals, we favor titanium for its cheapness and availability, nontoxicity, and well-known ability to catalyze a variety of stereoselective transformations, including oxidations with environmentally benign H₂O₂. In this personal account, we summarize the state-of-the-art of rational design of chiral titanium(IV) salan and salalen catalysts, and investigations of their catalytic reactivities and stereoselectivities in the epoxidations of olefins and oxidations of thioethers, unraveling the peculiarities and mechanisms of their catalytic action.