|
Isocomene
Isocomene is a sesquiterpene first isolated from the perennial herb southern goldenbush (''Isocoma wrightii''), from which it derives its name. Its unusual structure consisting of three fused cyclopentane rings was first described by Zalkow ''et al.'' in 1977. The first total synthesis of isocomene was published by M.C. Pirrung in 1979. The key steps are a Photocatalysis, photocatalyzed Intramolecular reaction, intramolecular [2 + 2] cycloaddition reaction followed by a rearrangement reaction which forms three contiguous Chirality (chemistry), chiral centers. References {{reflist Sesquiterpenes Cyclopentanes Cyclopentenes Tricyclic compounds ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sesquiterpene
Sesquiterpenes are a class of terpenes that consist of three isoprene units and often have the molecular formula C15H24. Like monoterpenes, sesquiterpenes may be cyclic or contain rings, including many unique combinations. Biochemical modifications such as oxidation or rearrangement produce the related sesquiterpenoids. Sesquiterpenes are found naturally in plants and insects, as semiochemicals, e.g. defensive agents or pheromones. Biosynthesis and examples The reaction of geranyl pyrophosphate with isopentenyl pyrophosphate results in the 15-carbon farnesyl pyrophosphate (FPP), which is an intermediate in the biosynthesis of sesquiterpenes such as farnesene. Cyclic sesquiterpenes are more common than cyclic monoterpenes because of the increased chain length and additional double bond in the sesquiterpene precursors. In addition to common six-membered ring systems such as the ones found in zingiberene and bisacurone, cyclization of one end of the chain to the other end can l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
