The trimethylsiloxydienes (2),(7),(9), and (11), react with tetrachlorocyclopropene (3) at room temperature to give the troponoids (6),(8),(10a), and (12), respectively; bromine oxidation of compound (14), derived from Diels–Alder reaction of diene (13) with dienophile (3), gives α- tropolone (10a) in 76% yield.
