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Six- versus five-membered ring formation in radical cyclization of 1-vinyl-5-methyl-5-hexenyl radicals

✍ Scribed by Ana M. Gómez; Marı́a D. Company; Clara Uriel; Serafı́n Valverde; J.Cristóbal López

Publisher
Elsevier Science
Year
2002
Tongue
French
Weight
74 KB
Volume
43
Category
Article
ISSN
0040-4039

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✦ Synopsis

Radical cyclization of 1-vinyl-5-methyl-5-hexenyl radicals (radical numbering) affords six-membered ring products prevailing over the isomeric five-membered ring compounds; the former are generated through two reaction pathways: 6-endo-trig ring closure and rearrangement of intermediate methylenecyclopentyl radicals obtained by 5-exo-trig cyclization.

📜 SIMILAR VOLUMES

Five vs six membered ring formation in t
Five vs six membered ring formation in the vinyl radical cyclization
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The ratio of methylenecyclopentane to methylenecyclohexane derivatives observed in the vinyl radical cyclization increases with the concentration of substrate and tin hydride.

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## Abstract 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 alkeny