Metalation at the allylic site (Me group) of (Z)-RCH:CHMe (R = alkyl) is more rapid than with the E-isomers regardless of the configuration in which the resultant organometallic is more thermodn. stable. Thus, (Z)-Me3CCH:CHCH2K is formed 15 times faster than its E-isomer, although the latter is thermodn. favored. Isomerization of the allylpotassium compds. in THF is very slow, but may be catalyzed by trace impurities, e.g., O. [on SciFinder (R)]