A unified synthetic strategy toward oroidin-derived alkaloids premised on a biosynthetic proposal

Abstract: Details of the evolution of a synthetic strategy toward the spirocyclic chlorocyclopentane core of oroidin-derived alkaloids, including the axinellamines and potentially adaptable to palau''amine, are described. A proposed refinement of the Kinnel–Scheuer biosynthetic proposal for palau''amine is posited. Studies undertaken to improve the regioselectivity and efficiency of a key Diels–Alder reaction utilizing a novel protecting group strategy, microwave chemistry, and other strategies are described. Further insights regarding the suitability of different protecting groups during the epoxidation/chlorination/ring contraction sequence are disclosed. Several interesting by-products from this reaction sequence are reported. These studies have led to a unified synthetic strategy to the axinellamines and palau''amine. [Copyright &y& Elsevier]