Eine einheitlich verlaufende aliphatische Benzilsäure‐Typ‐Umlagerung

Abstract

An Uniformly Occurring Aliphatic Benzil‐Benzilic‐Acid‐Type Rearrangement Treatment of 6‐bromo‐2,2,5,5‐tetramethylcyclohex‐3‐enone ( 2 ) with aqueous alkaline and air affords 1‐hydroxy‐2,2,5,5‐tetramethylcyclopent‐3‐enecarboxylic acid ( 8 ) as the major product of a benzil‐benzilic‐acid‐type rearrangement. The key compound is 2,2,5,5‐tetramethylcyclohex‐3‐ene‐1,2‐dione ( 11 ). The by‐product of the reaction is ( E )‐2,2,5,5‐tetramethylhex‐3‐enedioic acid ( 9 ) as the result of an oxidative cleavage of the 6‐membered ring and the isomerization of the double bond.