Konfigurative Zuordnung über sterisch definierte Epoxidringe. XI. Glycidonitrile. IV.1. Synthese von 1α‐Methyl‐2α‐aryl‐cyclohexan‐1ß‐carbonsäuren aus 4α‐Aryl‐2‐methyl‐1α‐oxaspiro. octan‐2‐nitrilen

Abstract

Determination of Configurations by the Aid of Sterically Corresponding Epoxides. XI. Glycidic Nitriles. IV. Synthesis of 1α‐Methyl‐2α‐aryl‐cyclohexane‐1ß‐carboxylic Acids from 4α‐Aryl‐2‐methyl‐1α‐oxaspiro[2, 5]octane‐2‐nitrilesThe opening of an epoxide ring of the C‐2‐isomeric glycidic nitriles 1a–b with anhydrous HCl in dry Et2O yields the corresponding chlorocyanohydrines 2a–b. Treatment of these chlorocyanohydrines with diluted NaOH does not give the expected α‐chloroketones 3a–b, but only the original glycidic nitriles. Dehydrocyanation of the chlorocyanohydrines 2a–b is carried out by column chromatography on silica or neutral Al2O3. Favorskii rearrangement of the resulting α‐chloroketones 3a–b gives the angular methylated carboxylic acid methyl esters 4a–b, which are converted to the acids 5a–b by saponification with NaOH in quantitative yield.Better reaction conditions for the Favorskii rearrangement of 1‐acetyl‐1‐chloro‐cyclohexanes are described.