EXTENDED PI-PARTICIPATION IN BIOMIMETIC CYCLIZATION OF SQUALENE DERIVATIVES

Chlorides 4,18,22-pentamethyl-5,9,13,17,21-tricosapentaenes) with vari ous phenyl substituents were prepared, and solvolysis rates were measu red in aqueous ethanol (phi = 95% and 80%) and in aqueous 2,2,2-triflu oroethanol (omega = 97%). Hammett rho(+) values obtained are -1.86, -1 .81 and -1.56, respectively, suggesting concerted cyclization of at le ast two double bonds in the rate determining step.