Abstract: Thermai rearrangements near 190" of various l-methoxy-2-oxobicyclo [3.2. 0] hepta- 3, 6-dienes to 3-methoxy-2-oxobicyclo [3.2. 0] hepta-3, 6-dienes having substituents at positions consistent with a Cope rearrangement formalism were first observed by Miyashi, Nitta, and Mukai in 1967. Similar rearrangements are now reported for l-ethoxybicyclo [3.2. O] hepta-3, 6-diene, 3-ethoxybicyclo [3.2. O] hepta-2, 6-diene, and the degenerate ...