60046-47-1Relevant academic research and scientific papers
Synthesis, characterization and first application of chiral C2-symmetric bis(phosphinite)-Pd(II) complexes as catalysts in asymmetric intermolecular Heck reactions
Karaka?, Duygu Elma,Durap, Feyyaz,Aydemir, Murat,Baysal, Akin
, p. 193 - 198 (2016/04/05)
A series of new chiral C2-symmetric bis(phosphinite) ligands and their palladium(II) complexes have been synthesized and for the first time used as catalysts in the palladium-catalysed asymmetric intermolecular Heck coupling reactions of 2,3-dihydrofuran with iodobenzene or aryl triflate. Under optimized conditions, products were obtained with high conversions and moderate to good enantioselectivities. The new C2-symmetric bis(phosphinite) ligands and their palladium(II) complexes were characterized using multinuclear NMR and Fourier transform infrared spectroscopies and elemental analysis.
Bis(phosphinite) with C2-symmetric axis; Effects on the ruthenium(II)-catalyzed asymmetric transfer hydrogenation of acetophenone derivatives
Aydemir, Murat,Durap, Feyyaz,Kayan, Cezmi,Baysal, Akin,Turgut, Ylmaz
, p. 2777 - 2784 (2013/02/22)
Chiral ruthenium catalyst systems generated in situ from [Ru(η6-p-cymene)(μ-Cl)Cl]complex and chiral Csymmetric bis(phosphinite) ligands based on amino alcohol derivatives were employed in the asymmetric transfer hydrogenation of aromatic ketones to give the corresponding optically active alcohols in high yield. The best results were obtained in the [Ru(η6-p-cymene)(μ-Cl)Cl]and (2S)-2-[benzyl(2-{benzyl[(2S)-1- [(diphenylphosphanyl)oxy]-3-phenyl propan-2-yl]amino}ethyl)amino]-3-phenylpropyl diphenylphosphinite or (2R)-2-[benzyl(2-{benzyl[(2R)-1-[(diphenylphosphanyl) oxy]-3-phenylpropan-2-yl]amino}ethyl)amino]-3-phenylpropyl diphenylphosphinite catalytic systems, which gave enantioselectivities of up to 93% ee and 99% conversion. Copyright
Pyridine containing chiral macrocycles: Synthesis and their enantiomeric recognition for amino acid derivatives
Deniz, Pinar,Turgut, Yilmaz,Togrul, Mahmut,Hosgoren, Halil
, p. 6227 - 6232 (2011/09/19)
Four novel C2-symmetric enantiomerically pure, chiral pyridine-18-crown-6 type macrocycles containing lipophilic chains at the stereogenic centers were prepared. The enantioselectivity of the new ligands toward the enantiomers of d-,l-amino acid methyl ester derivatives were also determined by 1H NMR titration method. These novel macrocycles have been showed to be strong complexing agents for d- and l-amino acid methyl ester hydrochloride salts (with Kass up to 13590 M-1 and G 0 up to 23.3 kJ mol-1 and selectivity ratio: 80:20) by 1H NMR titration methods. These macrocyclic hosts exhibited enantioselective binding towards the d-enantiomer of valine methyl ester hydrochloride with Kd/Kl up to 5.08 in CDCl3 with 0.25% CD3OD.
A short enantioselective synthesis of (-)-bestatin via l-proline-catalyzed α-amination of an aldehyde
George, Shyla,Suryavanshi, Gurunath S.,Sudalai, Arumugam
scheme or table, p. 6791 - 6793 (2009/04/06)
A short and high yielding enantioselective synthesis of (-)-bestatin, a naturally occurring aminopeptidase inhibitor, is described via l-proline-catalyzed asymmetric α-amination of 3-phenylpropionaldehyde as the key reaction. The methodology also involves a Pd-catalyzed intramolecular cyclization of an allylic acetate giving a trans-oxazoline in a highly diastereoselective manner (dr > 14:1).
Combining Magnetic Resonance Spectroscopies, Mass Spectrometry, and Molecular Dynamics: Investigation of Chiral Recognition by 2,6-di-O-Methyl-β-cyclodextrin
Franchi, Paola,Lucarini, Marco,Mezzina, Elisabetta,Pedulli, Gian Franco
, p. 4343 - 4354 (2007/10/03)
EPR spectroscopy has been employed to investigate the formation of complexes between heptakis-(2,6-O-dimethyl)-β-cyclodextrin (DM-β-CD) and different enantiomeric pairs of chiral nitroxides of general structure PhCH2N(O·)CH(R)R′. Accurate equilibrium measurements of the concentrations of free and included radicals afforded the binding constant values for these nitroxides. The relationship between the stereochemistry of the DM-β-CD complexes and the thermodynamics of complexation was elucidated by correlating EPR data with 1H-1H NOE measurements carried out on the complexes between DM-β-CD and the structurally related amine precursors of nitroxides. NOE data suggested that inclusion of the stereogenic center in the DM-β-CD cavity occurs only when the R substituent linked to the chiral carbon contains an aromatic ring. For these types of complexes, molecular dynamics simulation indicated that the depth of penetration of the stereogenic center into the cyclodextrin cavity is determined by the nature of the second substituent (R′) at the asymmetric carbon and is responsible for the observed chiral selectivity. Analysis of mass spectra showed that, for the presently investigated amines, electrostatic external adducts of CDs with protonated amines are detected by ESI-MS.
Lipase-catalyzed resolution and desymmetrization of 2-hydroxymethylaziridines
Davoli, Paolo,Caselli, Emilia,Bucciarelli, Maria,Forni, Arrigo,Torre, Giovanni,Prati, Fabio
, p. 1948 - 1953 (2007/10/03)
The Amano PS lipase-catalyzed acetylation of 2-hydroxymethylaziridines 1a-e has been investigated in order to evaluate the effect of ring substituents on the enantioselectivity of the reaction and to assess the stereochemical preference of the enzyme. N-Benzyl-3-substituted cis-aziridines displayed high enantioselectivity and higher E values were found when the bulkiness of the substituent in position 3 was increased. In contrast, the corresponding trans isomers showed only poor enantioselectivity, regardless of the steric hindrance of the substituent at C3. Removal of the N-benzyl group proved to be detrimental to the enantioselectivity. In addition, desymmetrization of meso dimethanolic cis-aziridine 1f was successfully accomplished, and the corresponding monoacetylated product 2f, which is related to a key intermediate used in the total synthesis of the mitomycin antibiotic FR-900482, was obtained in excellent yield and nearly enantiomerically pure form. Moreover, the absolute configuration of enantiomerically pure cis-aziridines was determined by chemical correlation and/or chiroptical techniques, thus showing the stereochemical preference of Amano PS lipase for the 2S enantiomer.
