Cross-linked poly(4-vinylpyridine/styrene) copolymers as a support for immobilization of ytterbium triflate
摘要:
Eight cross-linked poly(4-vinylpyridine/styrene) (P/S) resins (as beads) were prepared by radical suspension polymerization. Ytterbium triflate was immobilized in the range of 0.10-0.24 mmol/g by mixing with the P/S resins. The ytterbium triflate-immobilized P/S resins exhibited good activity in two Lewis acid-catalyzed reactions. Low pyridine containing resins were recycled with no loss of activity, while a slight loss of activity was observed with the higher pyridine containing resins. (c) 2005 Elsevier Ltd. All rights reserved.
An efficient and mild bismuth triflate-catalysed three-component Mannich-type reaction
作者:Thierry Ollevier、Etienne Nadeau
DOI:10.1039/b710794c
日期:——
In the presence of a catalytic amount of Bi(OTf)(3).4H(2)O, aldehydes together with amines react with silylenolates to afford the corresponding Mannich-type adducts smoothly. A wide variety of silylenolates derived from ketones, as well as esters and thioesters, react rapidly to afford the beta-amino ketones or the beta-amino esters in high yields (up to 94%).
Molecular Iodine-Catalyzed Imine Activation for Three-Component Nucleophilic Addition Reactions
作者:Kim Janda、Byoung Lee、Suresh Mahajan
DOI:10.1055/s-2005-868487
日期:——
β-Amino ketones and α-amino nitriles were synthesized from silyl enol ethers and trimethylsilyl cyanides, via a three-component nucleophilicadditionreaction with aromaticaldehydes and amines; the reaction was found to be significantly accelerated by molecular iodine under neutral conditions.
Novel method for catalyst immobilization using an ionic polymer: a case study using recyclable ytterbium triflate
作者:Byoung Se Lee、Suresh Mahajan、Kim D. Janda
DOI:10.1016/j.tetlet.2004.12.013
日期:2005.1
A series of ionic polymers prepared by quarternization of cross-linked poly(4-vinylpyridine/styrene) (P/S) resins with several alkylating agents, including short-length PEG mesylate were used as polymeric supports to immobilize Yb(OTf)(3). The efficacy of the polymer-bound catalyst was examined in a Mannich-type reaction. (C) 2004 Elsevier Ltd. All rights reserved.