Preparation of Cyclic .ALPHA.-Hydroxy Ketones from .DELTA.- and .EPSILON.-Keto Acids Induced by the Generation of a Novel Acyl Anion Equivalent from the Carboxyl Group.
作者:Hatsuo MAEDA、Haruka ASHIE、Toshihide MAKI、Hidenobu OHMORI
DOI:10.1248/cpb.45.1729
日期:——
An improved method for the transformation of keto acids into cyclic α-hydroxy ketones, induced by the electrochemical generation of a novel acyl anion equivalent from the carboxy group, has been developed. Both five- and six-membered rings were constructed by constant-current electrolysis of δ- and ε-keto acids in the presence of Bu3P using an undivided cell equipped with a graphite anode and a Pt cathode. Attempts to prepare four- and seven-membered ring carbocycles were unsuccessful. The electrochemical reaction was found to be highly stereoselective when cyclization took place onto cyclopentanone and substituted cyclohexanone rings. Stereochemical aspects of the formation of bicyclic products, especially those having a bicyclo[4.3.0]skeleton, are discussed.
开发了一种改进的方法,通过电化学生成从羧基衍生出的新型酰基阴离子等价物,诱导将酮酸转化为环状α-羟基酮。通过在配有石墨阳极和铂阴极的无隔膜电池中,在Bu3P存在下对δ-和ε-酮酸进行恒流电解,构建了五元和六元环。尝试制备四元和七元环碳环未能成功。当环化反应发生在环戊酮和取代环己酮环上时,发现该电化学反应具有高度立体选择性。讨论了双环产物形成的立体化学方面,特别是具有双环[4.3.0]骨架的产物。