1-Arylbutadiene was obtained when 1-aryl-1-acetoxy-3-butene was flashed through a quartz tube at 500-900°; at a higher temperature range, the Cope reaction occurred to give a cyclized compound (III) and its dehydrogenated product (IV). Pyrolysis of 4-pyridyl derivative (Id) at 830° gave quinoline (20%) besides isoquinoline. Similarly, 2-quinolyl derivative (Ie, 670°) afforded benzo [f] quinoline (10%) along with the normal products (IIe and IIIe). Formation of quinoline and benzo [f] quinoline must presumably involve 10- and 14-membered ring intermediates, respectively. Thus the total energies of 10 isomers expected to arise from 10- and 14-membered ring intermediates were calculated by the ω-method.
