text: In an early example of the use of a chiral auxiliary in asymmetric synthesis, E. J. Corey and coworkers conducted an asymmetric Diels-Alder reaction between (−)-8-phenylmenthol acrylate ester and 5-benzyloxymethylcyclopentadiene. The cycloaddition product was carried forward to the iodolactone shown below, an intermediate in the classic Corey synthesis of the prostaglandins. It is proposed that the back face of the acrylate is blocked by the auxiliary, so that cycloaddition occurs at the front face of the alkene.
  (−)-8-phenylmenthol can be prepared from either enantiomer of pulegone,
  though neither route is very efficient. Because of the widespread utility of the 8-phenylmenthol auxiliary, alternative compounds that are more easily synthesized, such as trans-2-phenyl-1-cyclohexanol 
  and trans-2-(1-pheyl-1-methylethyl)cyclohexanol have been explored.