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|Section2= |Section7= }} 1,2,3,4,5-Pentamethylcyclopentadiene is a cyclic diolefin with the formula C5Me5H (Me = CH3).〔Overview of Cp * Compounds: Elschenbroich, C. and Salzer, A. Organometallics: a Concise Introduction (1989) p. 47〕 1,2,3,4,5-Pentamethylcyclopentadiene is the precursor to the ligand ''1,2,3,4,5-pentamethylcyclopentadienyl,'' which is often denoted as Cp * (to signify the five methyl groups radiating from the periphery of this ligand as in a five-pointed star). In contrast to less substituted cyclopentadiene derivatives, Cp *H is not prone to dimerization. ==Synthesis== Pentamethylcyclopentadiene is commercially available. It was first prepared from tiglaldehyde via 2,3,4,5-tetramethylcyclopent-2-enone. Alternatively 2-butenyllithium adds to ethylacetate followed by acid-catalyzed dehydrocyclization: :2 MeCH=C(Li)Me + MeC(O)OEt → (MeCH=C(Me))2C(OLi)Me + LiOEt :(MeCH=C(Me))2C(OLi)Me + H+ → Cp *H + H2O + Li+ 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「pentamethylcyclopentadiene」の詳細全文を読む スポンサード リンク
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