Hydrolysis of hedycaryol: the origin of the eudesmols in the Myrtaceae

The steam distillates of the family Myrtaceae are often found to contain the three isomeric sesquiterpene alcohols, α-, β- and γ-eudesmol. Associated with these alcohols but not steam-distilled with them are two hydrates of eudesmol, cryptomeridiol and 4-epicryptomeridiol, compounds which have not been previously reported in the Myrtaceae. These five alcohols are the major by-products of the hydrolysis of hedycaryol, which can occur during leaf ageing or distillation. The use of H218O during distillation implicated the presence of hedycaryol prior to distillation by trapping the eudesmyl-carbocation formed during the hydrolysis.