454183-08-5Relevant articles and documents
Immobilization of (l)-valine and (l)-valinol on SBA-15 nanoporous silica and their application as chiral heterogeneous ligands in the Cu-catalyzed asymmetric allylic oxidation of alkenes
Samadi, Saadi,Ashouri, Akram,Rashid, Hersh I,Majidian, Shiva,Mahramasrar, Mahsa
, p. 17630 - 17641 (2021/10/04)
SBA-15 nanoporous silica was synthesized by hydrothermal method using P123 surfactant and tetraethoxyortosilicate in acidic condition and then functionalized by 3-chloropropyltrimethoxysilane. Next, by immobilization of chiral amino acid (S)-2-amino-3-methyl butanoic acid (l-valine) and chiral amino alcohol (S)-2-amino-3-methylbutane-1-ol (l-valinol), preparedviathe reduction ofl-valine by NaBH4/I2in THF, on functionalized-SBA-15, chiral heterogeneous ligands AL*-i-Pr-SBA-15 and AA*-i-Pr-SBA-15 were prepared and characterized by FT-IR, XRD, TGA, EDX, SEM, BET-BJH techniques. The asymmetric allylic oxidation of alkenes was done using copper-complexes of these ligands and the as-synthesized peresters. The reactions were optimized by varying various parameters such as temperature, solvent, amount of chiral heterogeneous ligand, as well as the type and amount of copper salt. Under optimized conditions, 6 mg of AL*-i-Pr-SBA-15 and 3.2 mol% of Cu(CH3CN)4PF6in acetonitrile at 50 °C, the chiral allylic ester was obtained with 80% yield and 39% enantiomeric excess in 24 h. The recyclability of the chiral heterogeneous catalysts was also evaluated without significant reduction in the reaction results up to three runs.
Heterogenization of chiral mono oxazoline ligands by grafting onto mesoporous silica MCM-41 and their application in copper-catalyzed asymmetric allylic oxidation of cyclic olefins
Samadi, Saadi,Jadidi, Khosrow,Khanmohammadi, Behnam,Tavakoli, Niloofar
, p. 344 - 353 (2016/07/06)
A series of chiral 4-oxazolinylaniline ligands 8 were conveniently synthesized on a gram scale from inexpensive and commercially available 4-aminobenzoic acid in four steps. The obtained organic chiral ligands have been covalently grafted onto ordered mesoporous silicas MCM-41 and the resulting inorganic–organic hybrid materials have been characterized by thermogravimetric analysis (TGA), differential thermal analysis (DTA), powder X-ray diffraction, BET and BJH nitrogen adsorption–desorption methods, energy-dispersive X-ray spectroscopy (EDX), CHN analysis, scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FT-IR). The catalytic and induced asymmetric effects of the chiral copper (I) complexes of these new chiral supported heterogeneous catalysts on the asymmetric allylic oxidation of cycloolefins were investigated under different conditions. Reactions using the catalyst exhibited moderate to good enantioselectivities, up to 80%, and good yields, up to 95% better than the corresponding homogeneous reaction. The catalyst could be recovered easily and reused five times without remarkable loss of reactivity, yield, or enantioselectivity. This is, to the best of our knowledge, the first heterogenization of chiral 4-oxazolinylaniline ligands on an inorganic (silica) surface and their application as a heterogeneous catalyst in the asymmetric Kharash–Sosnovsky reaction.
A significant improvement in enantioselectivity, yield, and reactivity for the copper-bi-o-tolyl bisoxazoline-catalyzed asymmetric allylic oxidation of cyclic olefins using recoverable SBA-15 mesoporous silica material
Samadi, Saadi,Nazari, Saber,Arvinnezhad, Hamid,Jadidi, Khosrow,Notash, Behrouz
supporting information, p. 6679 - 6686 (2013/07/26)
A series of chiral bi-o-tolyl bisoxazoline ligands 1 and 2 were conveniently synthesized on a gram scale from inexpensive and commercially available 3-methyl benzoic acid in eight steps. The catalytic and induced asymmetric effects of the chiral copper (I) complexes of these ligands on the asymmetric allylic oxidation of cycloolefins were investigated in the presence of various nano-sized additives. When SBA-15 mesoporous silica was used in conjunction with these ligands very highly enantioselectivities (up to 97% ee) and excellent yields (up to 99%) of the corresponding chiral allylic esters were obtained in a reasonably short period of time.
