Automerization in vinylidenecyclopentadiene and phenylcarbene
Abstract
Flash pyrolysis of vinylidencyclopentadiene at 800–1050°C results in carbon randomization; 2-methyl-vinylidenecyclopentadiene rearranges to styrene and benzocyclobutene, and [1-13C]phenyldiazomethane yields vinylidenecyclopentadiene carrying excess label at C(5) at 590°C and 5–7 mmHg of N2, thus suggesting that the ring contraction is reversible and occurs via bicyclo-[3.2.0]hepta-1,3,6-triene.