Dramatic Effect of Ancillary NHC Ligand in the Highly Selective Catalytic Oxidative Carbon–Carbon Multiple Bond Cleavage

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• 作者：Suraj K. Gupta ; Sandeep K. Sahoo ; Joyanta Choudhury
• 刊名：Organometallics
• 出版年：2016
• 出版时间：August 8, 2016
• 年：2016
• 卷：35
• 期：15
• 页码：2462-2466
• 全文大小：401K
• 年卷期：0
• ISSN：1520-6041

文摘

Selective and controlled oxidation of olefins to aldehydes is a commonly used important transformation in chemistry. However, chemists still use the dangerous and inconvenient ozonolysis method or the less selective, low-yielding Lemieux–Johnson protocol. In a program of developing effective catalysts for this important reaction, we disclose here that an ancillary ligand can play a dramatic role in the above catalytic phenomenon, depending on the design of the ligand precursor chosen. Proof-of-principle is demonstrated with the help of two newly designed [L_nRu^II-NHC] precatalysts (NHC = an imidazolydene-based NHC, Im-NHC, or a triazolydene-based NHC, Trz-NHC; L_n = para-cymene) for catalytic selective oxidation of olefins/alkynes to carbonyl compounds. With the electron-deficient Trz-NHC ligand, [(para-cymene)Ru^II(Im-Trz)]⁺ precatalyst was found to be an order of magnitude more efficient than the [(para-cymene)Ru^II(Im-NHC)]⁺ precatalyst.