The electrochemical cleavage of olefinic bonds in conjugated C5-C7-cycloalkenylbenzenes 1, indene 4a, and 1, 2-dihydronaphthalene (4b) results from anodic oxidation of these compounds in MeOH in an undivided cell. The process includes the formation of (1, 2- dimethoxycycloalkyl) benzenes 2a-c, 1, 2-dimethoxyindan (5a), and 1, 2-dimethoxytetralin (5b) as intermediates and leads to ω, ω-dimethoxy-ω-phenyl-n-C5-C7-alkanal dimethyl ...