Chemistry of Humulene Epoxides

Abstract

First paragraph: During the latter half of the 19th century there was considerable interest amongst chemists in those compounds derived from natural sources. In particular, the essential oils of a number of plants and related species provided a rich source of such compounds, principally of the terpene type. Within this group of naturally-occurring compounds the C15 sesquiterpenes were of particular interest largely as a result of their relatively high abundance. In 1895 , Chapman presented evidence of a new sesquiterpene, humulene, which he isolated from oil of hops. By the preparation of various derivatives, he was able to distinguish this hydrocarbon, previously called a-caryophyllene, from caryophyllene. However, largely because of the lack of spectroscopic techniques, it was not until much later that the structure of humulene was solved. Although it was commonly accepted in the early 1950’s that humulene embodied an eleven-membered ring with three double bonds, the exact juxtaposition of these olefinic linkages was the subject of much debate.