Hypervalent Iodine Chemistry: Mechanistic Investigation of the Novel Haloacetoxylation, Halogenation, and Acetoxylation Reactions of 1,4-Dimethoxynaphthalenes
摘要:
Treatment of 1,4-dimethoxynaphthalenes with iodosobenzene diacetate and trimethylsilyl chloride or bromide furnished the haloacetoxylated, acetoxylated, and halogenated 1,4-dimethoxynaphthalenes in excellent yield. The reaction pathway for each transformation was shown to be a function of reagent stoichiometry. A mechanistic hypothesis is presented that rationalizes the reaction pathways and explains the subtle differences in the halogenation reactions. The acetoxylation, for example, is thought to involve the formation of an iodonium ion that promotes the nucleophilic addition of acetate ion and subsequent 1,2-acetyl migration. Bromination occurs as a direct result of the oxidation of trimethylsilyl bromide to bromine, followed by electrophilic aromatic substitution. Chlorination is thought to proceed via a radical process and not the formation of molecular chlorine from the dissociation of iodosobenzene dichloride. The haloacetoxylation reaction also appears to be fairly specific for 1,4-dimethoxynaphthalenes, since the analogous reaction with a 1,4-dimethoxybenzene derivative was unsuccessful.
Direct Synthesis of Hydroquinones from Quinones through Sequential and Continuous‐Flow Hydrogenation‐Derivatization Using Heterogeneous Au–Pt Nanoparticles as Catalysts
Pt–Au bimetallic nanoparticlecatalysts immobilized on dimethyl polysilane (Pt–Au/(DMPSi‐Al2O3)) have been developed for selective hydrogenation of quinones to hydroquinones. High reactivity, selectivity, and robustness of the catalysts were confirmed under continuous‐flow conditions. Various directderivatizations of quinones, such as methylation, acetylation, trifluoromethanesulfonylation, methacrylation
固定在二甲基聚硅烷上的Pt-Au双金属纳米颗粒催化剂(Pt-Au /(DMPSi-Al 2 O 3))已开发用于将醌选择性加氢为对苯二酚。在连续流动条件下证实了催化剂的高反应活性,选择性和坚固性。在连续和连续流动条件下成功进行了醌的各种直接衍生化反应,例如甲基化,乙酰化,三氟甲磺酰化,甲基丙烯酸化和苯甲酰化,以良好的产率提供了所需的产品,甚至具有优异的收率。尤其是,对空气敏感的氢醌,如蒽氢醌和萘氢醌,可以在封闭的连续和连续流动条件下成功生成并衍生化而不会分解。
Byrde; Woodcock, Annals of Applied Biology, 1953, vol. 40, p. 675,677
作者:Byrde、Woodcock
DOI:——
日期:——
Inoue et al., Yuki Gosei Kagaku Kyokaishi, 1956, vol. 14, p. 622,624
作者:Inoue et al.
DOI:——
日期:——
Inoue et al., Bulletin of University of Osaka Prefecture, Series A: Engineering and Natural Sciences, 1959, vol. <A> 8, p. 31,34, 35