Au(I)-Catalyzed Cyclization of<i>tert</i>-Butyl Carbonates Derived from Homopropargyl Alcohols: A Catalytic Alternative to Cyclic Enol Carbonates
作者:Seunghoon Shin、Ji-Eun Kang
DOI:10.1055/s-2006-933110
日期:——
Au(I)-complexes catalyze cyclization of tert-butyl carbonates derived from a variety of homopropargyl alcohols. This procedure offers a catalytic alternative to stoichiometric Lewis acids for the preparation of a range of enol carbonates.
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)。
Amine functionalized layered double hydroxide: a reusable catalyst for aldol condensation
作者:Mitarani Sahoo、Sudarshan Singha、K. M. Parida
DOI:10.1039/c1nj20492k
日期:——
Zn : Al layered double hydroxide-supported 3-aminopropyltriethoxysilane (APTES) and N-methyl 3-aminopropyltriethoxy silane (MAPTES) are found to be efficient, environmentally attractive and selective solid base catalysts for liquid phase aldol condensation reactions at room temperature. The organic functionalized solid catalysts were characterized by XRD, FT-IR, Raman, EDX, SEM, TG-DTA, 13C and 29Si CP MAS NMR techniques. The XRD pattern indicated the anti-parallel monolayer arrangements of organic moieties in the interlayer space of LDH. 29Si NMR confirmed that the linking silicon atom is fully condensed in the framework. The reusability study shows consistent activity of the heterogeneous catalyst after several cycles.
Zn:Al层状双氢氧化物负载的3-氨丙基三乙氧基硅烷(APTES)和N-甲基3-氨丙基三乙氧基硅烷(MAPTES)被发现是高效的、环境友好的、选择性的固体碱催化剂,适用于室温下液相醛醇缩合反应。这些有机功能化的固体催化剂通过XRD、FT-IR、拉曼光谱、EDX、SEM、TG-DTA以及13C和29Si CP MAS NMR技术进行了表征。XRD图谱表明有机基团在LDH层间空间呈现反平行单层排列。29Si NMR证实连接的硅原子在框架中完全缩合。重复使用性研究显示出该非均相催化剂在多次循环后的一致活性。
A Selective Direct Aldol Reaction in Aqueous Media Catalyzed byZinc-Proline
The Zn–proline complex is shown to catalyze the aldolreaction of acetone and a wide range of arenecarbaldehydes in aqueous media, accepting even deactivated arenecarbaldehydes such as methoxybenzaldehydes in good yields. Enantiomeric excesses of up to 56 % could be obtained with 5 mol-% of the catalyst at room temperature, and up to 66 %
Highly enantioselective biomimetic intramolecular dehydration: kinetic resolution of β-hydroxy ketones catalyzed by β-turn tetrapeptides
作者:Zhi-Xue Du、Li-Yuan Zhang、Xin-Yuan Fan、Feng-Chun Wu、Chao-Shan Da
DOI:10.1016/j.tetlet.2013.03.087
日期:2013.5
Racemic beta-hydroxy ketones were kinetically resoluted into the enantiopure isomers and (E)-alpha,beta-unsaturated ketones using catalytic asymmetric intramolecular dehydration for the first time. Synthetic tetrapeptides were used to imitate fatty acid dehydratases to efficiently discriminate racemic beta-hydroxy ketones, enantioselectively catalyze the intramolecular dehydration, and result in highly enantioenriched beta-hydroxy and (E)-alpha,beta-unsaturated ketones in the environmentally benign process. Mechanistically, the high discrimination of the racemic substrates and successive enantioselective dehydration are highly dependent on the cooperative catalysis of the NH2 and COOH groups of the peptide. (C) 2013 Elsevier Ltd. All rights reserved.