The chiral monoaza-15-crown-5 lariat ethers annellated to methyl-4,6-O-benzylidene-α-d-glucopyranoside-1 or mannopyranoside 2 have been applied as phase-transfercatalysts in the epoxidation of substituted chalcones and chalcone analogues with tert-butylhydroperoxide resulting in significant asymmetricinduction. It was found that the position of the substituents in the aromatic ring of the chalcone
Visible light-mediated oxidative quenching reaction to electron-rich epoxides: highly regioselective synthesis of α-bromo (di)ketones and mechanism study
作者:Lin Guo、Chao Yang、Lewei Zheng、Wujiong Xia
DOI:10.1039/c3ob41245h
日期:——
A novel and simple procedure was developed for the regioselective synthesis of α-bromo (di)ketones from electron-rich epoxides viavisiblelightphotoredoxcatalysis. Through optimization of solvent and light source, the reaction can be rapidly achieved under mild conditions. Moreover, the possible reaction mechanism was proposed and further supported by control experiments.
Layered Double Hydroxides-Supported Diisopropylamide: Synthesis, Characterization and Application in Organic Reactions
作者:M. Lakshmi Kantam、A. Ravindra、Ch. Venkat Reddy、B. Sreedhar、B. M. Choudary
DOI:10.1002/adsc.200505266
日期:2006.3
The layereddoublehydroxides-supporteddiisopropylamide (LDH-DA) catalyst is found to be an efficient and selective solid base for aldol, Knoevenagel, Henry, Michael, transesterification and epoxidation reactions under liquid phase conditions. LDH-DA is synthesized by the interaction of lithium diisopropylamide with LDH-NO3 (as-synthesized) and calcined LDH-NO3. The LDH-DA (Mg/Al, 3/1) and their precursors
发现层状双氢氧化物负载的二异丙基酰胺(LDH-DA)催化剂是在液相条件下用于醇醛,Knoevenagel,Henry,Michael,酯交换和环氧化反应的有效且选择性的固体碱。LDH-DA是通过二异丙基氨基锂与LDH-NO 3(合成后)和煅烧的LDH-NO 3相互作用而合成的。通过使用各种仪器技术,如FT-IR,TGA和DTA,粉末XRD,固态27 Al MAS NMR光谱,SEM和XPS(ESCA ),可以很好地表征LDH-DA(Mg / Al,3/1)及其前体)。
Diaryl-2-pyrrolidinemethanols catalyzed enantioselective epoxidation of α,β-enones: new insight into the effect of structural modification of the catalyst on reaction efficiency
作者:Alessandra Lattanzi、Alessio Russo
DOI:10.1016/j.tet.2006.10.005
日期:2006.12
Catalytic enantioselectiveepoxidation of α,β-unsaturated ketones promoted by diaryl-2-pyrrolidinemethanols and tert-butyl hydroperoxide (TBHP) is described. Investigation on structural modifications of the diaryl-2-pyrrolidinemethanols showed that fine tuning of the stereoelectronics of the substituents on the aryl moiety is important to achieve high efficiency. By employing a structurally optimized
An easy access to bioactive 13-hydroxylated and 11,13-dihydroxylated sesquiterpene lactones (SLs) through Michael addition of a nucleophilic hydroxyl group
作者:Francisco A. Macías、María D. García-Díaz、Guillermo M. Massanet、José F. Gómez-Madero、Frank R. Fronczek、Juan C.G. Galindo
DOI:10.1016/j.tet.2008.09.024
日期:2008.12
The addition of a hydroxyl group to α,β-unsaturated carbonyl systems provides a new and easy access to bioactive difunctionalized sesquiterpene lactones (SLs) through a Michael addition to the α-methylene-γ-lactone system. The use of HMPA to enhance the nucleophilic properties of the hydroxyl groups and to stabilize the enolate is discussed. Also, we present a proposal for the mechanism based on the