95979-82-1Relevant academic research and scientific papers
Highly efficient Rh-catalyzed asymmetric hydrogenation of α,β-unsaturated nitriles
Yan, Qiaozhi,Kong, Duanyang,Li, Meina,Hou, Guohua,Zi, Guofu
, p. 10177 - 10181 (2015/09/01)
A highly efficient enantioselective hydrogenation of α,β-unsaturated nitriles catalyzed by Rh-(R,R)-f-spiroPhos complex has been developed. With Rh-(R,R)-f-spiroPhos catalyst and under mild conditions, a wide range of α,β-unsaturated nitriles including the (E)- and (Z)-isomers of 3-alkyl-3-aryl, 3,3-diaryl, and 3,3-dialkyl α,β-unsaturated nitriles were hydrogenated to the corresponding chiral nitriles with excellent enantioselectivities (up to 99.9% ee) and high turnover numbers (TON up to 10,000).
Catalytic asymmetric formation of δ-Lactones from Unsaturated acyl halides
Tiseni, Paolo S.,Peters, Rene
supporting information; experimental part, p. 2503 - 2517 (2010/09/03)
Previously unexplored enantiopure zwitterionic ammonium dienolates have been utilized in this work as reactive intermediates that act as diene components in hetero-Diels-Alder reactions (HDAs) with aldehydes to produce optically active δ-lactones, subunits of numerous bioactive products. The dienolates were generated in situ from E/Z mixtures of a,b- unsaturated acid chlorides by use of a nucleophilic quinidine derivative and Sn (OTf)2 as co-catalyst. The latter component was not directly involved in the cycloaddition step with aldehydes and simply facilitated the formation of the reactive dienolate species. The scope of the cycloaddition was considerably improved by use of a complex formed from Er- (OTf)3 and a simple commercially available norephedrine-derived ligand that tolerated a broad range of aromatic and heteroaromatic aldehydes for a cooperative bifunctional Lewis-acid-/ Lewis-base-catalyzed reaction, providing a,b-unsaturated d-lactones with excellent enantioselectivities. Mechanistic studies confirmed the formation of the dienolate intermediates for both catalytic systems. The active ErIII complex is most likely a monomeric species. Interestingly, all lanthanides can catalyze the title reaction, but the efficiency in terms of yield and enantioselectivity depends directly on the radius of the Ln III ion. Similarly, use of the pseudolanthanides ScIII and YIII also resulted in product formation, whereas the larger La III and other transition metal salts, as well as main group metal salts, proved to be inefficient. In addition, various synthetic transformations of 6- CCl3- or 4-silyl-substituted α,β-unsaturated d-lactones, giving access to a number of valuable δ-lactone building blocks, were investigated.
Catalytic asymmetric formation of δ-lactones by [4+2] cycloaddition of zwitterionic dienolates generated from α,β-unsaturated acid chlorides
Tiseni, Paolo S.,Peters, Rene
, p. 5325 - 5328 (2008/03/18)
Smooth elaboration: Versatile δ-lactone building blocks are provided by tertiary amine-catalyzed asymmetric [4+2] cycloadditions of α,β-unsaturated acid chlorides and the electron-poor aldehyde chloral (see scheme). Silyl-substituted acid chlorides (R1 = R 3Si) can be used for the diastereoselective synthesis of β-hydroxy-δ-lactones possessing quaternary stereocenters. (Chemical Equation Presented).
Enantioselective Conjugate Reduction of α,β-Unsaturated Carboxamides with Semicorrin Cobalt Catalysts
Matt, Peter von,Pfaltz, Andreas
, p. 691 - 700 (2007/10/02)
Chiral semicorrin cobalt complexes, prepared in situ from cobalt(II) chloride and the free ligands, are efficient, highly enantioselective catalysts for the conjugate reduction of α,β-unsaturated carboxamides with sodium borohydride.Enantiomeric excesses of up to 99percent, essentially quantitative yields, and high substrate/catalyst ratios (1000-10 000:1) are attractive attributes of this catalytic process.
