Reductive free-radical alkylations and cyclisations mediated by 1-alkylcyclohexa-2,5-diene-1-carboxylic acids
作者:Paul A. Baguley、John C. Walton
DOI:10.1039/a802024h
日期:——
1-alkylcyclohexa-2,5-diene-1-carboxylic acids were prepared by Birch reduction–alkylation of benzoic acid and their efficiency as mediators of alkyl radical chain addition and cyclisation processes was investigated. Reductive alkylations were respectably successful, even with only one or two equivalents of alkene, for secondary, tertiary and benzylic radicals. Reaction of 1-[2-(cyclohex-2-enyloxy)ethyl]cyclohexa-2
通过对苯甲酸进行Birch还原-烷基化反应,制备了一系列1-烷基环六-2,5-二烯-1-羧酸,并研究了它们作为烷基链加成和环化过程的介质的效率。对于仲,叔和苄基,即使仅使用一或两个当量的烯烃,还原烷基化也相当成功。1-反应[2-(环己-2-烯基氧基)乙基]环己-2,5-二烯-1-羧酸,得到的产品外切- TRIG -cyclisation,即7-氧杂二环[4.3.0]壬烷,在产率与氢化三丁基锡诱导的3-(2'-碘乙氧基)环己烯的环化反应相当。这以及exo-和end的隔离1- [2-(6,6-二甲基双环[3.1.1]庚-2-烯-2-基甲氧基)乙基]环六-2,5-二烯-1-羧酸的环化产物确定闭环也可以用这些试剂令人满意地介导。制剂完全不含金属污染物,并且在添加或环化之前完全不存在烷基的直接还原。然而,所需的产物伴随有烷基苯,以及引发剂分解的副产物,并且这种复杂的后处理。在反式的桦木还原烷基化中未能获得1-