Enantioselektive katalytische Hydrierung von α‐(Acetylamino)‐zimtsäure mit einem Rhodium‐Phosphankomplex in wäßriger Lösung

Abstract

Enantioselective Catalytic Hydrogenation of a-(Acetylamino)cinnamic Acid with a Rhodium Phosphane Complex in Aqueous SolutionThe synthesis of [(3R,4R)-3,4-bis(diphenylphosphino)-l,l-dimethylpyrrolidini~-P,~](l,5-cyc1ooctadiene)rhodium bis(tetrafluoroborate) (5) is described. With this water-soluble catalyst the sodium salt 6c of u-(Acetylamino)cinnamic acid (6a) is hydrogenated in aqueous solution to give (S)-N-acetylphenylalanine with 90% ee.

Towards Sustainable Catalysis – Highly Efficient Olefin Metathesis in Protic Media Using Phase Labelled Cyclic Alkyl Amino Carbene (CAAC) Ruthenium Catalysts

“…In general, two main approaches are applied in the synthesis of aqueous catalyst systems (1) grafting the catalyst to water soluble polymers and (2) synthesis of catalysts containing highly polar, small tags such as cationic quaternary ammonium salts or anionic sulfonyl groups …”

Bisphosphine ligands containing two o-N,N-dimethylanilinyl substituents at each phosphorus atom

“…The amino-bisphosphine systems, which have been reviewed (6), have been developed mainly with the aim of surmounting the severe problem in homogeneous catalysis of separating the catalyst from the reaction products. Approaches to solving this problem, including representative literature references, have been: (i) to "heterogenize" the homogeneous catalyst by incorporating it into an insoluble polymer via attachment through the N atom (5,(7)(8)(9); (ii) to solubilize the catalyst in water (in which the reactants and products are only slightly miscible) by quaternization of the N atom via protonation or alkylation (10)(11)(12)(13)(14)(15)(16); (iii) to water solubilize the catalyst via incorporation of a sulfonate group within an elaborated N-containing functionality (17); and (iv) to extract the catalyst postreaction with aqueous acid in which the product does not dissolve (18,19).…”

Organotransition-metal complexes of multidentate ligands. 10. Steric vs. electronic control on formation of six- and seven-coordinate carbonyl halides of molybdenum(II) and tungsten(II)

“…Atomic positional parameters and selected bond lengths and bond angles are given in Tables I and II, respectively. This Structure of (H2CPz"2)W(CO)3Br2 (7) showing the atomic numbering scheme and 50% probability thermal ellipsoids.…”