pre-MIBSKは、名古屋大学の石原らが開発した超原子価ヨウ素を有するアルコール酸化触媒です。Dess-Martin試薬に比べ、使用量が触媒量でよく活性種が系中で発生するため、低コストかつ安全に扱うことが可能です。さらに第2級アルコールの酸化も進行することに加え、第一級アルコールの酸化に関しては共酸化剤のOxone®の量を調節することでアルデヒドとカルボン酸の作り分けも可能です。
〈参考文献〉
Uyanik, M., Akakura, M., Ishihara, K. : J. Am. Chem. Soc., 2009, 131, 251. DOI: 10.1021/ja807110n
[2] “2-Iodoxy-5-Methylbenzenesulfonic Acid-Catalyzed Selective Oxidation of 4-Bromobenzyl Alcohol to 4-Bromobenzaldehyde or 4-Bromobenzoic Acid with Oxone”Electron-donating group-substituted 2-iodoxybenzoic acids (IBXs) such as 5-Me-IBX (1g), 5-MeO-IBX (1h), and 4,5-Me2-IBX (1i) were superior to IBX 1a as catalysts for the oxidation of alcohols with Oxone (a trademark of DuPont) under nonaqueous conditions, although Oxone was almost insoluble in most organic solvents. The catalytic oxidation proceeded more rapidly and cleanly in nitromethane. Furthermore, 2-iodoxybenzenesulfonic acid (IBS, 6a) was much more active than modified IBXs. Thus, we established a highly efficient and selective method for the oxidation of primary and secondary alcohols to carbonyl compounds such as aldehydes, carboxylic acids, and ketones with Oxone in nonaqueous nitromethane, acetonitrile, or ethyl acetate in the presence of 0.05−5 mol % of 6a, which was generated in situ from 2-iodobenzenesulfonic acid (7a) or its sodium salt. Cycloalkanones could be further oxidized to α,β-cycloalkenones or lactones by controlling the amounts of Oxone under the same conditions as above. When Oxone was used under nonaqueous conditions, Oxone wastes could be removed by simple filtration. Based on theoretical calculations, we considered that the relatively ionic character of the intramolecular hypervalent iodine−OSO2 bond of IBS might lower the twisting barrier of the alkoxyperiodinane intermediate 16.
Uyanik, M., Ishihara, K. Org. Synth. 2012, 89, 105. DOI:10.15227/orgsyn.089.0105
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