title: Asymmetric Pauson-Khand reactions using camphor-derived chelating thiols as chiral controllers.
abstract: A convenient procedure for the preparation of enantiopure 10-(R-thio)-2-exo-bornanethiols from (1S)-camphor-10-thiol has been developed. The ethynyl derivatives of these thiols gave excellent diastereoselectivities (up to 98:2) in Pauson-Khand reactions with norbornene and norbornadiene through the intermediacy of a chelated dicobalt pentacarbonyl complex. Thermal reaction conditions starting from the preformed chelated complex gave better results than N-oxide-promoted runs with in situ generation of the chelated intermediate. The corresponding adducts have been elaborated through a protocol consisting of conjugate addition, samarium iodide-promoted cleavage of the chiral auxiliary, and retro-Diels-Alder reaction to afford 4-substituted 2-cyclopentenones in high enantiomeric purity.
authors.affiliation: Unitat de Recerca en Síntesi Asimètrica, Departament de Química Orgànica, Universitat de Barcelona, Martí i Franqués 1-11, 08028 Barcelona, Spain.
authors.forename: I
authors.initials: I
authors.lastname: Marchueta
authors.forename: E
authors.initials: E
authors.lastname: Montenegro
authors.forename: D
authors.initials: D
authors.lastname: Panov
authors.forename: M
authors.initials: M
authors.lastname: Poch
authors.forename: X
authors.initials: X
authors.lastname: Verdaguer
authors.forename: A
authors.initials: A
authors.lastname: Moyano
authors.forename: M A
authors.initials: MA
authors.lastname: Pericàs
authors.forename: A
authors.initials: A
authors.lastname: Riera