化学学报 ›› 2015, Vol. 73 ›› Issue (10): 1002-1006.DOI: 10.6023/A15050355 上一篇    下一篇

研究通讯

可再生型高价碘试剂亚碘酰二内酯在高效醇氧化中的应用研究

宋爱茹a,b, 张弛a   

  1. a 南开大学元素有机化学国家重点实验室 天津化学化工协同创新中心 天津 300071;
    b 天津师范大学 天津市水资源与水环境重点实验室 天津 300387
  • 投稿日期:2015-05-24 发布日期:2015-07-17
  • 通讯作者: 张弛 E-mail:zhangchi@nankai.edu.cn
  • 基金资助:

    项目受国家自然科学基金(Nos.21172110,21472094,21421062)资助.

Iodosodilactone as a Recyclable Oxidant for Efficient Oxidation of Alcohols to Carbonyl Compounds

Song Airua,b, Zhang Chia   

  1. a State Key Laboratory of Elemento-Organic Chemistry, Collaborative Innovation Center of Chemical Science and Engineering, Nankai University, Tianjin 300071, China;
    b Tianjin Key Laboratory of Water Resources and Environment, Tianjin Normal University, Tianjin 300387
  • Received:2015-05-24 Published:2015-07-17
  • Supported by:

    Project supported by the National Natural Science Foundation of China (Nos. 21172110, 21472094, 21421062).

利用商品化的高价碘试剂亚碘酰二内酯(Iodosodilactone)作为最终氧化剂, 配合催化量的氮氧自由基2,2,6,6-四甲基哌啶-1-氧自由基(TEMPO)和当量的4-二甲氨基吡啶(DMAP)所组成的反应体系可以将含有不同官能团的伯醇快速高效地氧化为相应的醛且不会发生过度氧化; 将反应体系中的催化剂换为空间位阻较小的氮氧自由基1-甲基-2-金刚烷氮氧自由基(1-Me-AZADO)则可以将仲醇高效地氧化为相应的酮. 值得指出的是, 反应结束后Iodosodilactone的还原态2-碘-间苯二甲酸和DMAP可以通过简单的过滤及酸碱中和处理进行回收, Iodosodilactone的再生可通过用次氯酸钠/盐酸体系氧化2-碘-间苯二甲酸来高效实现.

关键词: 亚碘酰二内酯, 可再生型, 高价碘试剂, 醇氧化, 氮氧自由基

Various primary alcohols can be selectively oxidized to the corresponding aldehydes in excellent yields by iodosodilactone in the presence of a nitroxyl radical catalyst 2,2,6,6-tetramethylpiperidin-1-yloxy (TEMPO) and stoichiometric amount of 4-dimethylaminopyridine (DMAP) in chloroform under reflux. On the other hand, secondary alcohols can be oxidized to the corresponding ketones efficiently with a structurally less hindered nitroxyl radical catalyst 1-methyl-2-azaadamantane N-oxyl (1-Me-AZADO) instead of TEMPO. The mechanism of this alcohol oxidation reaction has been proposed. First, a zwitterion intermediate A was formed after the ligand exchange around the iodine(III) atom; then A would oxidize the nitroxyl radical TEMPO to its oxoammonium salt C, which was responsible for the oxidation of alcohols and was reduced to the hydroxylamine D. Finally, D was oxidized by A to C to re-start the next alcohol oxidation cycle. Note that both DMAP and 2-iodo-isophthalic acid (the reduced form of iodosodilactone) can be recovered easily after reaction. A representative procedure for the alcohols oxidation and the recovery of DMAP and the regeneration of iodosodilactone are as follows: Iodosodilactone (217 mg, 0.75 mmol) was added to a solution of an alcohol (0.5 mmol), TEMPO (7 mg, 0.04 mmol) and DMAP (73 mg, 0.6 mmol) in CHCl3 (5 mL) at room temperature, the reaction mixture was refluxed until the alcohol was no longer detected (TLC). Then the mixture was cooled to room temperature, filtered and washed with CH2Cl2 (60 mL). The filtrate was washed sequentially with 1 mol/L HCl, 10% Na2CO3, and brine. Then the organic layer was dried over anhydrous Na2SO4 and concentrated in vacuum. Flash column chromatography was applied to give the corresponding pure carbonyl compound. The residue collected during the previous filtration step was stirred in aqueous HCl (5%, 50 mL) and then filtered. The obtained aqueous phase was neutralized to pH 8~9 by saturated aqueous NaOH solution to release DMAP, then DMAP was extracted with CH2Cl2 (30 mL×3), the organic layer was dried over anhydrous Na2SO4 and concentrated in vacuum to afford the recovered DMAP in 90% yield. At last, the treatment of the combination of the aqueous phase after CH2Cl2 extraction and the residue collected in the latest filtration with concentrated HCl (2 mL) and aqueous NaClO solution (5.84%, 4 mL) led to the regeneration of oxidant iodosodilactone in 93% yield.

Key words: iodosodilactone, recyclable, hypervalent iodine reagent, alcohol oxidation, nitroxyl radical