Thermal reorganization of α- and β-thujene : A degenerate rearrangement of the vinylcyclopropane type

Abstract α-Thujene (I) racemizes on being heated at 250°. By examination of deuterium-labelled α-thujene, the racemization was demonstrated to be a degenerate example of the vinylcyclopropane type of rearrangement. Thermal reorganization of β-thujene (IV) leads to two products (V and VI), the more rapidly formed of which (V) seems also to arise by a vinylcyclopropane type of rearrangement.