Preparation of intermediates for the synthesis of polycyclic alkaloids: A new access to the azabicyclic core of the Stemona alkaloids

Several isoxazolidines, derived from the 1,3-dipolar cycloaddition of α,β-hexenolides to cyclic nitrones, were converted into the corresponding piperidine- and pyrrolidine-oxepinones by reduction of the nitrogen-oxygen bond. The potential of the resulting amino alcohols as synthetic precursors of polycyclic alkaloids was explored. These intermediates provide a new access to the 1-azabicyclo[5.3.0]decane core of the Sfemona alkaloids. © Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.