A Simple and Improved Procedure for the Conversion of Alkynes to 1,2-Diketones by Indirect Electrooxidation With Ruthenium Tetroxide as a Mediator
作者:Sigeru Torii、Tsutomu Inokuchi、Youzou Hirata
DOI:10.1055/s-1987-27950
日期:——
Indirect electrooxidation of alkynes 1 using ruthenium tetroxide as a mediator, leading to 1,2-diones 2 in 72-87%, is described. The electrolysis is carried out in the presence of a catalytic amount of ruthenium dioxide dihydrate in a two phase system of saturated aqueous sodium chloride and carbon tetrachloride. The overoxidation of 1,2-diones to the corresponding carboxylic acid, an unavoidable drawback generally encountered in the metal oxidation of acetylenes, is suppressed greatly by maintaining the pH of the aqueous phase at 4 and conducting the reaction at 0-5°C. The synthetic utility of this electrochemical oxidation is exemplified by the preparation of 2i (82%), a key intermediate for the synthesis of furaneol 4, from the commercially available 1i.
使用四氧化钌作为介质,对炔烃1进行间接电氧化,以72-87%的产率得到1,2-二酮2。电解在含有催化量二氧化钌二水合物的水和四氯化碳两相体系中进行,使用饱和氯化钠水溶液。通过将水相的pH维持在4,并在0-5°C下进行反应,可以大大抑制1,2-二酮过氧化成相应的羧酸,这是通常在金属氧化炔烃中遇到的一个不可避免的缺点。这种方法的合成实用性通过从市售的1i制备关键中间体2i(产率82%)来证明,2i是合成furaneol 4的重要中间体。