|
|Section2= |Section3= }} Humulene, also known as α-humulene or α-caryophyllene, is a naturally occurring monocyclic sesquiterpene (C15H24), containing an 11-membered ring and consisting of 3 isoprene units containing three nonconjugated C═C double bonds, two of them being triply substituted and one being doubly substituted. It was first found in the essential oils of ''Humulus lupulus'' (hops), from which it derives its name.〔Glenn Tinseth, "Hop Aroma and Flavor", January/February 1993, Brewing Techniques. ==Preparation and synthesis== Humulene is one of many sesquiterpenoids that are derived from farnesyl diphosphate (FPP). The formation of humulene from FPP is catalyzed by sesquiterpene synthesis enzymes.〔Moss, G.P., "Humulene derived sesquiterpenoid biosynthesis." International Union of Biochemistry and Molecular Biology Enzyme Nomenclature. Accessed April 10, 2011. http://www.enzyme-database.org/reaction/terp/humul.html〕 This biosynthesis can be mimicked in the laboratory by preparing allylic stanane from farnesol, termed Corey synthesis. There are diverse ways to synthesize humulene in the laboratory, involving differing closures of the C-C bond in the macrocycle. The McMurry synthesis uses a titanium-catalyzed carbonyl coupling reaction; the Takahashi synthesis uses intramolecular alkylation of an allyl halide by a protected cyanohydrin anion; the Suginome synthesis utilizes a geranyl fragment; and the de Groot synthesis synthesizes humulene from a crude distillate of eucalyptus oil.〔Goldsmith, David. "The total synthesis of natural products". Canada: John Wiley & Sons. 1997 pp 129-133〕 Humulene can also by synthesized using a combination of four-component assembly and palladium-mediated cyclization, outlined below. This synthesis is noteworthy for the simplicity of the C−C bond constructions and cyclization steps, which it is believed will prove advantageous in the synthesis of related polyterpenoids. :left To understand humulene's regioselectivity,the fact that one of the two triply substituted C═C double bonds is significantly more reactive,its conformational space was explored computationally and four different conformations were identified. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Humulene」の詳細全文を読む スポンサード リンク
|
