Electric Literature of 19132-06-0, Chemistry is a science major with cience and engineering. The main research directions are chemical synthesis, new energy materials, nano-ceramics, nano-hybrid composite materials, preparation and modification of special coatings. 19132-06-0, Name is (2S,3S)-Butane-2,3-diol,introducing its new discovery.
New enantiopure P,P-bidentate bis(diamidophosphite) ligands. Application in asymmetric rhodium-catalyzed hydrogenation
Two series of new enantiopure bidentate bis(diamidophosphite) ligands with diazaphospholidine and diazaphosphepine heterocyclic backbones were prepared. The ligands have a highly modular structure, which is well suited to the synthesis of a small library of compounds. Preparation was accomplished by the successive addition of enantiomerically pure substituted diamines (N,N?-dibenzylcyclohexane-1,2-diamine (1), N,N?-dimethylcyclohexane- 1,2-diamine (2), and N,N?-dimethyl-1,1?-binaphthyl-2,2?- diamine (3)) and enantiomerically pure diols (butanediol (a), cyclohexanediol (b), di-O-isopropylidenethreitol (c), and binaphthol (d)) to phosphorus trichloride. The corresponding bis(diamidophosphite) selenides were prepared, and the 1JPSe values were calculated in order to evaluate the sigma-donor ability of the new ligands. The cationic Rh(I) complexes [Rh(COD)(P,P)]BF4 were synthesized with 8 of the 12 new bis(diamidophosphite) ligands. The complexes were used as catalytic precursors for the asymmetric hydrogenation of benchmark substrates, namely methyl alpha-acetamidoacrylate (4), methyl (Z)-alpha-acetamidocinnamate (5), and dimethyl itaconate (6). The influence of the nature of both the terminal and bridging fragments of the bis(diamidophosphite) ligands on the asymmetric induction is discussed. Most proved to be effective catalysts for the process, attaining total conversion and excellent enantioselectivity (>99% ee) with the complex containing the (R;Ral,Ral;R)-3c ligand in the hydrogenation of the three substrates. The best performing catalytic precursor [Rh(COD)((R;Ral,Ral;R)-3c)]BF4 was tested in the hydrogenation of selected cyclic enamides (7-9) and beta-acetamidoacrylate (10).
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Reference：
Synthesis and Crystal Structure of a Chiral C3-Symmetric Oxygen Tripodal Ligand and Its Applications to Asymmetric Catalysis,
Chiral lanthanide(III) complexes of sulphur–nitrogen–oxygen ligand derived from aminothiourea and sodium D-camphor-β-sulfonate