Planar-chiral cyrhetrenes for the rhodium-catalyzed asymmetric 1,4-addition and the hydrogenation of enamides.
[reaction: see text] The syntheses of novel cyrhetrenes 7a-c and 8a,b are described. These planar-chiral, mono- and diphosphines have been applied as ligands in the Rh-catalyzed 1,4-addition reaction to activated olefins and in the Rh-catalyzed hydrogenation of enamide 12, giving the corresponding products with up to 97 and 93% ee, respectively.
Stemmler
René T
RT
Institut für Organische Chemie der RWTH Aachen, Landoltweg 1, D-52056 Aachen, Germany.
Bolm
Carsten
C