Ein effizienter Zugang zu 1,5-Dihydropentalen und 2-Methyl-1,5-dihydropentalen aus Acrolein und Methacrolein
作者:Axel G. Griesbeck
DOI:10.1055/s-1990-26815
日期:——
Acrolein and methacrolein can be converted into 1,5-dihydropentalene and its 2-methyl derivative, respectively, by a simple, three-step process. [4+2]Cycloaddition of the aldehydes with cyclopentadiene affords 5-formyl-2-norbornenes which readily undergo condensation with cyclopentadiene to give 5-(cyclopentadienylidenemethyl)-2-norbornenes. These protected 6-vinylpentafulvenes undergo retro-cleave to cyclopentadiene and the 1,5-dihydropentalenes on vacuum flash thermolysis.
通过简单的三步法,丙烯醛和甲基丙烯醛可分别转化为 1,5-二氢戊烯及其 2-甲基衍生物。醛与环戊二烯发生 [4+2]环加成反应,生成 5-甲酰基-2-降冰片烯,这些降冰片烯很容易与环戊二烯发生缩合反应,生成 5-(环戊二烯亚甲基)-2-降冰片烯。 这些受保护的 6-乙烯基五烯在真空闪蒸热解过程中会逆裂解为环戊二烯和 1,5-二氢戊烯。