| Affiliation: | 1. Institute of Chemical Research of Catalonia (ICIQ), CERCA, Barcelona Institute of Science and Technology, Av. Països Catalans 16, 43007 Tarragona, Spain;2. Institute of Chemical Research of Catalonia (ICIQ), CERCA, Barcelona Institute of Science and Technology, Av. Països Catalans 16, 43007 Tarragona, Spain Departament de Química Analítica i Química Orgànica, Universitat Rovira i Virgili, C/Marcel⋅lí Domingo s/n, 43007 Tarragona, Spain |
| Abstract: | Two different classes of stereoselective cyclizations have been developed using a chiral auxiliary approach with commercially available [JohnPhosAu(MeCN)SbF6] as catalyst. First, a stereoselective cascade cyclization of 1,5-enynes was achieved using the Oppolzer camphorsultam as chiral auxiliary. In this case, a one-pot cyclization-hydrolysis sequence was developed to directly afford enantioenriched spirocyclic ketones. Then, the stereoselective alkoxycyclization of 1,6-enynes was mediated by an Evans-type oxazolidinone. A reduction-hydrolysis sequence was selected to remove the auxiliary to give enantioenriched β-tetralones. DFT studies confirmed that the steric clash between the chiral auxiliary and alkene accounts for the experimentally observed diastereoselective cyclization through the Si face. |
