The Phenylsulfonyl Group as an endo Stereochemical Controller in Intramolecular Pauson-Khand Reactions of 3-Oxygenated 1,6-Enynes Financial support of this work by the Ministerio de Educación y Cultura (DGES, project PB96-0021) and Comunidad de Madrid (project 07B/28/1999) is gratefully acknowledged |