Addition and Cyclization Reactions in the Thermal Conversion of Hydrocarbons with an Enyne Structure, 5. High-Temperature Ring Closures of 1,3-Hexadien-5-ynes to Naphthalenes – Competing Reactions via Isoaromatics, Alkenylidene Carbenes, and Vinyl-type Radicals
作者:Jörg Hofmann、Kathrin Schulz、Annett Altmann、Matthias Findeisen、Gerhard Zimmermann
DOI:10.1002/jlac.199719971218
日期:1997.12
2-ethynylstyrenes 7a–c were subjected to high-temperature pyrolysis. The cycloisomerization products isolated suggest that these are formed by three competing processes: by (i) an electrocyclic or a molecule-induced, (ii) an alkenylidene carbene controlled, and (iii) a radical-controlled ring-closure process. To estimate the relative importance of these three reactions here mentioned, the substrates have
对4-取代的1-苯基-1-丁烯-3-炔1a-c和2-乙炔基苯乙烯7a-c进行了高温热解。分离出的环异构化产物表明,它们是由三个竞争过程形成的:(i)电环或分子诱导的;(ii)链烯基卡宾控制的,和(iii)自由基控制的闭环过程。为了评估此处提到的这三个反应的相对重要性,分别在700和650°C的无氧氮气中和在甲苯中按比例取代的氮气中异构化了底物。这些异构化的相对贡献不仅取决于转化温度,而且还对在取代基- [R 1或7。