A highly efficient catalytic kinetic resolution of 2,3-epoxy 3-aryl ketones via asymmetric ring-opening with pyrazole derivatives has been achieved by using a chiral N,N′-dioxide–Sc(iii) complex as the catalyst.
Asymmetric epoxidation of α,β-unsaturated ketones catalyzed by rare-earth metal amides RE[N(SiMe<sub>3</sub>)<sub>2</sub>]<sub>3</sub>with chiral TADDOL ligands
作者:Haiwen Shan、Chengrong Lu、Bei Zhao、Yingming Yao
DOI:10.1039/d0nj05228k
日期:——
The catalyticasymmetric epoxidation of α,β-unsaturatedketones by tert-butylhydroperoxide (TBHP) has been well established using rare-earth metal amides RE[N(SiMe3)2]3 (RE = La(1), Nd(2), Sm(3), Y(4), Yb(5)) with chiral TADDOL ligands. It was found that the combination of Yb[N(SiMe3)2]3 and chiral TADDOL ligand H2L2 ((4S,5S)-2,2-dimethyl-α,α,α′,α′-tetra-3,5-bis(trifluormethylphenyl)-1,3-dioxolane-4
<font>β</font>-Cyclodextrin in Water: Highly Versatile and Green Approach for Biomimetic Regioselective Ring Opening of Chalcone Epoxides with Nitrogen Heterocycles
作者:Sumit Kumar、Naveen Kumar Konduru、Nishant Verma、Naseem Ahmed
DOI:10.1080/00397911.2015.1093142
日期:2015.11.17
The formation of new C-C bond through highly regioselectiveringopening of chalcone epoxides to nitrogen-containing heterocycles has been effectively worked out in impressive yields with heterocyclic nucleophiles such as pyrrole, indole, and 2-methyl indole in the presence of β-cyclodextrin using water as solvent at room temperature within 25–50 min. Water, an environmentally friendly reaction medium
摘要 使用杂环亲核试剂如吡咯、吲哚和 2-甲基吲哚,在 β-环糊精存在下,通过查耳酮环氧化物高度区域选择性开环形成含氮杂环,形成新的 CC 键已得到有效解决,产率令人印象深刻。水作为溶剂在室温下在 25-50 分钟内。水是一种环境友好的反应介质,首次用于这些杂环亲核试剂与查耳酮环氧化物作为其 β-环糊精配合物的反应,得到 1,3-二芳基-2-羟基-3-(1H-3-吲哚基/2-吡咯基)丙-1-酮(3a-u)。催化剂可以很容易地回收和循环使用多次而不会损失活性。图形概要
Synthesis of N-Containing Heterocycles via Mechanochemical Grinding and Conventional Techniques
作者:Amin F.M. Fahmy、Amira A. El-Sayed、Magdy M. Hemdan、Aya I. Hassaballah、Ahmed F. Mabied
DOI:10.14233/ajchem.2017.20798
日期:——
Mechano heterocyclic chemistry is a recent quickly growing technique draws the attention of hetrocyclic chemists towards the use of grindstone technique in a solvent free green efficient clean synthesis of many heterocyclic systems. a,b-Epoxy ketones were used as a unique scaffold for synthesis of stable hydroxyazoles. The key advantage of grinding technique over the conventional thermal technique includes its simple, solvent free conditions, as well as facile work up with high yield economy. It is also successful in achieving three of the green chemistry objectives of a solvent free, high atom economy, save energy thus combining the features of both economic and environmental advantages.
LiBr/β-CD/IBX/H<sub>2</sub>O-DMSO: A new approach for one-pot biomimetic regioselective ring opening of chalcone epoxides to bromohydrins and conversion to 1,2,3-triketones
作者:Nishant Verma、Sumit Kumar、Naseem Ahmed
DOI:10.1080/00397911.2017.1315537
日期:2017.6.3
ABSTRACT Highly regioselective ring cleavage of chalcone epoxides to bromohydrins has been carried out in good yields with LiBr in the presence of β-CD using DMSO-H2O as solvent system. The ring-opened product, i.e., bromohydrin, was well adapted to IBX-mediated oxidation in such a fashion that the bromohydrins are transformed to their corresponding 1,2,3-triketones in moderate-to-good yields in one