engleski

Extended pi-Participation in Biomimetic Cyclization of Squalene Derivatives

Chlorides 1-aryl-1-chloro-5, 9, 14, 18, 22-pentamethyl-5, 9, 13, 17, 21-tricosapentaenes with various phenyl substituents were prepared, and solvolysis rates were measured in 95% (v/v) and 80% (v/v) aqueous ethanol, and in 97% (wt./wt.) aqueous 2, 2, 2-trifluoroethanol. Hammett rho(+)values obtained are -1.86, -1.81 and -1.56, resp., suggesting concerted cyclization of at least two double bonds in the rate determining step.

extended pi-participation; neighboring group participation; concerted reaction; solvolysis; Hammett sigma; rho(+) correlation

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