Preparation of Enantiomerically Pure Compounds Employing Anodic Oxidations of Carboxylic Acids – A Late Review of Research Done in the 1980ies

Abstract

AbstractThere are widely unknown enantiopure building blocks and non‐conventional transformations described in this old work that could become useful in today's diversity‐oriented organic synthesis world. Coupling and mixed couplings of functionalized CF3‐substituted chiral radicals by Kolbe electrolysis of carboxylic acids lead to hexafluoro‐hexane‐2,5‐diol and to butyro‐ and valerolactone derivatives with functional‐group relationships that normally require components with reactivity umpolung. Oxidative decarboxylation of amino‐acid and peptide derivatives by Hofer‐Moest electrolyses provide entry into the synthetic use of chiral acyliminium‐ion intermediates. Chiral oxazoline and thioazoline building blocks (from serine, threonine, and cysteine) are accessible for substitutions and cycloadditions. The stereochemical course of oxidative CO2H replacement in serine by nucleophilically introduced groups with retention of configuration is discussed.