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

Autor:	Matthias Findeisen, Jörg Hofmann, Gerhard Zimmermann, Annett Altmann, Kathrin Schulz
Rok vydání:	1997
Předmět:	Enyne Radical Organic Chemistry chemistry.chemical_element General Chemistry Ring (chemistry) Photochemistry Toluene Nitrogen chemistry.chemical_compound Cycloisomerization chemistry Physical and Theoretical Chemistry Carbene Pyrolysis
Zdroj:	Liebigs Annalen. 1997:2541-2548
ISSN:	1099-0690 0947-3440
DOI:	10.1002/jlac.199719971218
Popis:	The 4-substituted 1-phenyl-1-butene-3-ynes 1a–c and the 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 been isomerized in oxygen-free nitrogen and in nitrogen proportionally substituted by toluene at 700 and 650 °C, respectively. The relative contributions of these isomerizations depend not only on the conversion temperature but also on the substitutent R in 1 or 7.
Databáze:	OpenAIRE
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