A stereoselectivesynthesis of (−)-allosedamine is disclosed. β-Aminosulfoxide 4 was generated stereoselectively by condensation of the sulfinyl anion 2 with N-Ts imine 3. The bromohydrin 5 was obtained by intramolecular sulfinyl group participation and the piperidine ring of allosedamine was elaborated using the ring-closing metathesis (RCM) reaction.
A novel, unprecedented transformation of 8-hydroxysulfoxides into substituted tetrahydrofurans by a silicon promoted Pummerer type reaction is disclosed. The transformation is shown to be general and is brought about under very mild reaction conditions. The products with the Sulfide group at the anomeric carbon provide a suitable handle to carry out further transformations. (C) 2003 Elsevier Ltd. All rights reserved.