Nucleophile-dependent stereodivergence in the Pd-catalyzed intramolecular cyclization of 2-(p-tolylsulfinyl)allylacetates

The palladium-catalyzed intramolecular cyclization of the sodium salts of N-Boc or N-trifluoroacetyl substituted 4-acetoxy-5-(p-tolylsulfinyl)-5-hexenylamines (1a,b) and 5-acetoxy-6-(p-tolylsulfinyl)-6-heptenylamines (2a,b) gives the corresponding 2-(1-(p-tolylsuifinyl)ethenyl)-pyrrolidines (3a,b and 4a,b) and piperidines (5a,b and 6a,b) in 50-88% yield and up to 90% diastereomeric excess. The major cycloadducts obtained in the trifluoroacetamide and NHBoc series were epimeric at the cl-nitrogen stereogenic carbon, thus indicating a stereoselectivity dependence on the nitrogen anionic nucleophile. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.