Pyrrolizidine Alkaloids via Intramolecular Palladium-Catalysed Allylic Alkylation: Synthesis of (+-)-Isoretronecanol

An efficient and stereoconvergent approach to 3-substituted hexahydroindol-2-one derivatives by palladium-catalysed intramolecular allylic alkylation has been developed. Subsequently, the straightforward conversion of the hexahydroindol-2-one 7d into the alkaloid (±)-isoretronecanol has been performed. The synthesis entails 11 steps starting from 1,3-cyclohexadiene, affording the final target in a 29% overall yield.