Caryophyllene

 Caryophyllen or (−)-β-caryophyllene, is a natural bicyclic sesquiterpene that is a constituent of many essential oils, especially clove oil, the oil from the stems and flowers of Syzygium aromaticum (cloves),[3] the essential oil of It is usually found as a mixture with isocaryophyllene (the. cis double bond isomer) and α-humulene (obsolete name: α-caryophyllene), a ring-opened isomer. Caryophyllene is notable for having a cyclobutane ring, as well as a trans-double bond in a 9-membered ring, both rarities in nature.

The first total synthesis of caryophyllene in 1964 by E.J. Corey was considered one of the classic demonstrations of the possibilities of synthetic organic chemistry at the time.