Selective copper(II)-catalyzed aerobic oxidative cleavage of aromatic gem-disubstituted alkenes to carbonyl compounds under neutral and mild conditions

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• 作者：Md. Munkir Hossain ; Shin-Guang Shyu
• 关键词：Alkene ; Aerobic ; Oxidation ; Carbonyl ; Copper
• 刊名：Tetrahedron
• 出版年：14 January, 2014
• 年：2014
• 卷：70
• 期：2
• 页码：251-255
• 全文大小：1254 K

文摘

Three copper(II) catalytic systems, CuCl₂路2H₂O, CuCl₂路2H₂O+phenanthroline, and [Cu(渭-Cl)Cl(phen)]₂ were used to cleave alkenes to their corresponding carbonyl compounds under aerobic and neutral conditions. [Cu(渭-Cl)Cl(phen)]₂ shows enhanced selectivity over the other two catalytic systems. The oxidative cleavage reactions were carried out in mixed H₂O/THF solvent system under oxygen (4聽atm) at 60掳C. The real oxidant is 2-hydroperoxytetrahydrofuran, which is generated in situ in the process through the reaction between THF and oxygen catalyzed by copper(II). The cleavage reactions are selective for aromatic gem-disubstituted alkenes. Aromatic internal alkenes are slow to be oxidized, and both aliphatic terminal and internal alkenes are inert to oxidative cleavage. Free radical scavenger 2,2,6,6, tetramethylpiperidinyl-1-oxyl (TEMPO) deactivates the reaction indicating the involvement of free radical path in the reaction mechanism.