Asymmetric Catalytic Syntheses of Pharmaceutically Important<i>β</i>-Amino-<i>α</i>-Hydroxyl Esters by Enantioselective Aminolysis of Methyl Phenylglycidate
作者:Rajkumar Tak、Manish Kumar、Tusharkumar Menapara、Manoj Kumar Choudhary、Rukhsana I. Kureshy、Noor-ul H. Khan
DOI:10.1002/cctc.201601208
日期:2017.1.23
Chiral macrocyclic CrIII salen complexes have been synthesized, characterized, and used as catalysts in the asymmetric aminolysis of aromatic ester epoxides with various anilines to prepare the β‐amino‐α‐hydroxyl esters in very good yield (up to 95 %) along with high diastereo‐ and enantioselectivity (dr>99/1, ee up to 96 %) under the optimized condition particularly with CrIII complex 4, which was
已合成,表征了手性大环Cr III salen配合物,并用作各种苯胺的芳香族酯环氧化物的不对称氨解中的催化剂,制备了β-氨基-α-羟基酯,收率很高(高达95%),而且在优化的条件下,尤其是使用Cr III配合物4时,具有很高的非对映选择性和对映选择性(dr > 99/1,ee高达96%),有效地循环了四次。
Chiral macrocyclic salen Mn(III) complexes catalyzed enantioselective epoxidation of non-functionalized alkenes using NaOCl and urea H2O2 as oxidants
作者:Nabin Ch. Maity、Sayed H.R. Abdi、Rukhsana I. Kureshy、Noor-ul H. Khan、E. Suresh、Ganga P. Dangi、Hari C. Bajaj
DOI:10.1016/j.jcat.2010.10.002
日期:2011.1.3
Two new chiral Mn(III) macrocyclic salen complexes 1a and 1b were prepared for the enantioselective epoxidation of non-functionalized alkenes. A 5 mol% loading of these catalysts in the presence of pyridine N-oxide as an axial base and sodium hypochlorite or urea hydrogen peroxide adduct as oxidant worked well to give respective epoxides in high yields and ee (up to >95% in selected cases). The catalyst
Organic carbonates as solvents in macrocyclic Mn(III) salen catalyzed asymmetric epoxidation of non-functionalized olefins
作者:Nabin Ch. Maity、Ganga V.S. Rao、K.J. Prathap、Sayed H.R. Abdi、Rukhsana I. Kureshy、Noor-ul H. Khan、Hari C. Bajaj
DOI:10.1016/j.molcata.2012.10.021
日期:2013.1
Organic carbonates, e.g., dimethyl carbonate and propylene carbonate were used as reaction media in enantioselective epoxidation of non-functionalized alkenes by using a series of chiral macrocyclic Mn(III) salen complexes (5 mol%) as catalyst with pyridine N-oxide as an axial base. This protocol worked effectively with urea hydrogen peroxide, as well as sodium hypochlorite as oxidants to give respective epoxides in high yields and ee (up to >91% in selected cases). Furthermore kinetic studies of the catalytic epoxidation reaction in dimethyl carbonate:methanol (optimized solvent mixture) with urea hydrogen peroxide as an oxidant showed first order dependence on catalyst and oxidant whereas it is zero order for the substrate, styrene. (c) 2012 Elsevier B.V. All rights reserved.