The case of the missing acetylene. The mechanism of an intramolecular SN(V) reaction and a new route to 1-methylbenzo[de]quinolines
作者:David R. W. Hodgson、Anthony J. Kirby、Neil Feeder
DOI:10.1039/a900090i
日期:——
1-Halogeno-2-(1-naphthyl)alkenes with a dimethylamino group in the peri position are smoothly converted to 1-methylbenzo[de]quinoline under mild conditions, in a process involving the loss of MeBr rather than HBr. The Z-bromide is 45 times more reactive than its E-isomer, and 7 times more reactive than the Z-chloride. These systems were designed to show efficient elimination of HBr, but acetylene is not a likely intermediate. There is good evidence to support both of two alternative addition–elimination mechanisms: a 6-endo-dig route which would involve a “normal” addition–elimination process in an unusual setting; and a tandem 5-exo-dig Michael addition–carbene rearrangement. The evidence so far does not permit a final choice between the two.
邻位具有二甲氨基的 1-卤代-2-(1-萘基)烯烃在温和条件下顺利转化为 1-甲基苯并[去]喹啉,该过程涉及损失 MeBr 而不是 HBr。 Z-溴化物的反应性是其E-异构体的45倍,是Z-氯化物的反应性的7倍。这些系统旨在有效消除 HBr,但乙炔不太可能是中间体。有充分的证据支持两种替代的添加 - 消除机制: 6-endo-dig 路线将涉及不寻常环境中的“正常”添加 - 消除过程;以及串联的 5-exo-dig 迈克尔加成-卡宾重排。迄今为止的证据还不允许在两者之间做出最终选择。