51593-59-0Relevant academic research and scientific papers
Enantioselective Catalysis, 4. Synthesis of N-Substituted (R,R)-3,4-Bis(diphenylphosphino)pyrrolidines. The Use of their Rhodium Complexes for the Asymmetric Hydrogenation of α-(Acylamino)acrylic Acid Derivatives
Nagel, Ulrich,Kinzel, Elke,Andrade, Juan,Prescher, Guenter
, p. 3326 - 3343 (2007/10/02)
A simple synthesis of (R,R)-3,4-bis(diphenylphosphino)pyrrolidine (6a) and some N-substituted derivatives 6b-m is described. 6l and 6m are optically active tetraphosphanes, composed of two (R,R)-3,4-bis(diphenylphosphino)pyrrolidine units and a dicarboxylic residue.The structure of the parent compound 6a was determined by X-ray diffraction.From the phosphanes 6a-m the cationic 1,5-cyclooctadiene-bisphosphane-rhodium complexes 7a-m were prepared.The complexes 7l and 7m are ligand bridged bis(rhodium) dications.The complexes 7a-m were used for the asymmetric catalytic hydrogenation of the α-(acylamino)acrylic acid derivatives 9a-l.Enantiomeric excesses up to 100percent were achieved.Between 1 and 70 at the optical yields do not depend on the hydrogen pressure.The substrate/catalyst ratio can be as high as 50000/1.
Asymmetric Catalyses. V. Enantioselective Amino Acid Synthesis by Hydrogenation of Prochiral Olefins with Rh-Complexes of the New Optically Active Chelating Phosphane Norphos
Brunner, Henri,Pieronczyk, Willigis,Schoenhammer, Beate,Streng, Karin,Bernal, Ivan,Korp, Jim
, p. 1137 - 1149 (2007/10/02)
Racemic bicyclohept-5-ene-2,3-diylbis(diphenylphosphane oxide), NorphosO, can be resolved with (-)-di-O-benzoyltartaric acid, (-)-DBW.The X-ray structure analysis of the diastereomer (-)-NorphosO/(-)-DBW, which is less soluble in ethanol, exhibits strong hydrogen bonds between the carboxylic groups of DBW and the PO groups.The bonding of the DBW-carboxylic groups to different NorphosO units leads to the formation of infinite close-packed chains.From the internal comparison with (-)-DBW the absolute configuration follows as (2R,3R) for (-)-Norphos.The chelating phosphanes (+)- and (-)-Norphos, obtained by SiHCl3-reduction of (+)- and (-)-NorphosO, respectively, afford neutral and cationic Rh-complexes which, with H2 at room temperature and atmospheric pressure within a few hours, give quantitative hydrogenation of α-(acetylamino)cinnamic acid, α-(acetylamino)acrylic acid and Dopa precursors.The optical yields vary between 79 and 97percent.
