摘要
The tetracyclic nucleus of puupehenone, 15-oxopuupehenol and other sesquiterpene–phenol natural products can be assembled stereoselectively in three steps, the last of these being the 6-endo-trig cyclisation of an alpha-keto radical generated from a substituted 2-(2-cyclohexenyl)ethyl 3-bromo-4-chromanone under metal-free conditions.