A Straightforward Synthesis of Trideuterated α‐Terpinene for Mechanistic Studies

Abstract

Regiospecifically trideuterated (2,6,6‐2H3)‐α‐terpinene was prepared in six steps and with a deuterium incorporation of >99 % in 24 % yield from 1,4‐cyclohexanedione monoethylene ketal. The synthetic procedure involved twofold cross‐coupling reactions of alkylcuprates (lithium dimethylcuprate and chloromagnesium cyano(isopropyl)cuprate, respectively) with enol triflates to introduce the alkyl substituents on the 1,3‐cyclohexadiene backbone. By changing the alkylcuprates, the synthetic approach could serve as a prototype for the synthesis of various 1,4‐dialkyl‐substituted 1,3‐cyclohexadiene derivatives, which could be deuterium‐labeled as well, for example for mechanistic studies.