Products and Reaction Routes in the Diozonolysis of 2,3-Dimethyl-1,3-butadiene in Methanol

Article abstract of DOI:10.1021/jo00222a004

Treatment of 2,3-dimethyl-1,3-butadiene (1) with 2 molar equiv of ozone in methanol afforded the abnormal products acetic acid (12) and methyl acetate (13), which resulted from cleavage of both the double bonds and the single bond of the conjugated diene system.In model experiments it was shown that the reaction proceeds stepwise by formation of an α,β-unsaturated methoxy hydroperoxide (3) in the first and a α-keto methoxy hydroperoxide (8) in the second ozonolysis step.The latter undergoes spontaneous decomposition at ambient temperatures to give rise to the abnormal cleavage products 12 and 13.This cleavage is accompanied by emission signals in the 1H NMR spectrum which are indicative of the occurrence of acetyl radicals and hence suggest at least a partial radical-type cleavage of the α-keto methoxy hydroperoxide 8.