Macrocyclic compounds. Part XIII. Isomerisation of macrocyclic alkadienes by potassium dispersed on alumina

Abstract

Data for the isomerisation at 25° of cyclic alkadienes with ring sizes from C₁₀ to C₂₆ complements the data obtained earlier (200°) with triethylborane as catalyst. Although no true equilibrium could be reached on the potassium–alumina catalyst used (the conjugated isomer was slowly reduced to the cyclic alkene), the positional isomer distribution in the stationary state confirms that conformational preferences for certain isomers are more accentuated at this low temperature.