Cascade Annulation Reactions To Access the Structural Cores of Stereochemically Unusual Strychnos Alkaloids

A new cascade annulation reaction has been developed to access the core structures of a novel family of strychnos alkaloids with a unique stereochemical arrangement. The new annulation cascade is facilitated by the development of a robust reaction sequence to access extremely sensitive N-acyl-iminium ions. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim Germany, 2009)