A Biogenetically Based Strategy Towards the Polycyclic Core Skeleton of Sarain A

An approach to the polycyclic core of sarain A, based upon a proposed biogenetic route, is presented. Condensation of a protected amino acid with a bromoacrylamide and subsequent addition of malonaldehyde sodium salt and methyl iodide afforded, after stereoselective hydrogenation, a highly functionalized diazabicyclo[4.3.0]nonane system 16. This intermediate possesses the stereochemistry required for the synthesis of the core skeleton of sarain A, a model of which (31) was obtained by an allylsilane strategy previously described by Weinreb and co‐workers. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)