SYNTHESIS OF SUBSTITUTED CYCLOOCTATETRAENIDE DIANIONS

Dilithioalkyl and -aryl monosubstituted cyclooctatetraenide dianions (Li2C8H7R; R = methyl, n-butyl, sec-butyl, tert-butyl, phenyl, and benzyl) were synthesized by reaction of the appropriate organolithium reagent with cyclooctatetraene in diethyl ether or tetrahydrofuran. The reaction occurred cleanly and with a good yield of the dilithio monosubstituted cyclooctatetraenide dianion at ambient or lower temperature for all alkyl or aryl organolithium reagents studied except tert-butyllithium. (TMEDA is needed as an activator for CH3Li.) A two-step mechanism for the reaction is proposed that involves addition of the organolithium reagent to cyclooctatetraene followed by proton removal to yield the appropriate dianion. © 1979, American Chemical Society. All rights reserved.