Manganese-Catalyzed Direct Oxidation of Methyl Ethers to Ketones
Manganese-Catalyzed Direct Oxidation of Methyl Ethers to Ketones
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DOI：
10.1002/asia.200900420
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发表时间：
2010-01-01
影响因子：
4.1
通讯作者：
Inoue, Masayuki
中科院分区：
文献类型：
--
作者：
Kamijo, Shin;Amaoka, Yuuki;Inoue, Masayuki
Alkyl ether linkages generally exhibit high chemical stability under a wide array of synthetic procedures and reaction conditions. Therefore, such ethers are often employed as protective groups for hydroxyl functionalities,[1] which are present in a number of naturally occurring substances of biological and synthetic interest. During syntheses of multihydroxylated molecules, judicious choice of protective groups, and their selective introduction and removal, are extremely important issues. Accordingly, a number of ethereal protective groups have been designed and developed, and various substituted benzyl ethers are among the most frequently employed in organic synthesis. On the other hand, the simplest, most robust methyl ethers have received less attention mainly owing to the harsh acidic conditions required for deprotection.[2]We envisioned that direct sp3 CÀH oxidation [3] under mild conditions should be useful for oxidative removal of methyl ethers, because CÀH bonds in the position α to the oxygen atom are generally susceptible to oxidation.[4] A number of oxidizing agents have been reported to perform one-step oxidation of dialkyl ethers to the corresponding carbonyl products. Among them, dioxirane [5] and oxaziridine [6] are representative non-metallic stoichiometric reagents for oxidation of dialkyl ethers. Several metal catalysts, such as Ru, Cr, Mn, and Fe, are also reported to oxidize ethers when utilized with a stoichiometric amount of primary oxidant.[4, 7] However, the starting ethers are restricted mainly to cyclic ethers, and systematic studies on metal-catalyzed oxidation of acyclic alkyl ethers are scarce.[8] We herein report a direct oxidation method of methyl ethers to ketones using a newly developed reagent system that involves a catalytic amount of Mn reagent and m-chloroperbenzoic acid (mCPBA).[9, 10]
