Tetraarylphosphonium inner-salts (TAPIS) as both Lewis base catalyst and phase tag
摘要:
Tetraarylphosphonium inner-salts (TAPIS) have been designed, synthesized and verified as recyclable and reusable Lewis base catalysts. The resulted TAPIS catalyst has been successfully applied in Michael addition, cyanation and trifluoromethylation reactions. (C) 2017 Elsevier Ltd. All rights reserved.
Addition of a variety of 1,3-dicarbonyl derivatives to conjugated nitroalkenes was efficiently performed under heterogeneous catalysis by acidic alumina in the presence of a minimum amount of solvent (Et2O, 0.5 mL/mmol). The procedure allows satisfactory to good yields of a diastereomeric mixture (Ë1:1) of polyfunctionalized adducts. Moreover, work-up can be avoided since the reaction mixture can be directly charged into a chromatographic column for immediate purification.
The lipase-catalyzed asymmetric C–C Michael addition
作者:Jian-Feng Cai、Zhi Guan、Yan-Hong He
DOI:10.1016/j.molcatb.2010.11.011
日期:2011.3
The example of enzyme-catalyzed asymmetric C-C Michael addition was observed using Lipozyme TLIM (immobilized lipase from Thermomyces lanuginosus) in organic medium in the presence of water. This biocatalysis is applicable to the Michael additions of a wide range of 1,3-dicarbonyl compounds and cyclohexanone to aromatic and heteroaromatic nitroolefins and cyclohexenone. The enantioselectivities up to 83% ee and yields up to 90% were achieved. The enzyme can be reused for three cycles. (C) 2010 Elsevier B.V. All rights reserved.
Agarwal, Jyoti; Naganaboina, Ram Tilak; Peddinli, Rama Krishna, Indian Journal of Chemistry - Section B Organic and Medicinal Chemistry, 2013, vol. 52, # 4, p. 511 - 518
Tris-ureas as versatile and highly efficient organocatalysts for Michael addition reactions of nitro-olefins: Mechanistic insight from in-situ diagnostics
作者:Milan Bera、Tamal Kanti Ghosh、Bidyut Akhuli、Pradyut Ghosh
DOI:10.1016/j.molcata.2015.01.004
日期:2015.11
Tris(2-aminoethyl)-amine, TREN based tris-ureas (1a-1d) and tris-thiourea (1e) have been explored towards a wide range of catalytic Michael addition reactions. These tris-ureas, 1a-1d efficiently catalyze the addition reaction of beta-nitro styrenes (2a-2d) with various nucleophiles such as beta-ketoesters (3a-3c), 1,3-dicarbonyl compound (3d), a cyanoester (3e) and a nitroester (3f) under ambient conditions to produce corresponding nitro alkanes in high yields. Pentafluorophenyl attached tris-urea, 1d is found to be the most effective catalyst in the series that yields 78-98% products conversion. In case of the reaction between beta-nitro styrenes and malononitrile (3g) in presence of 1d, 2-amino-5-nitro-4,6-diphenylcyclohex-1-ene-1,3,3-tricarbonitriles are also isolated as a minor product along with the corresponding Michael adduct. The added advantage of bridge-head nitrogen center in tris-urea organocatalysts, 1a-1d has been established by studying analogous benzene platform based tris-ureas (1f, 1g, 1h) in similar experimental conditions. Furthermore, a plausible reaction mechanism has also been established based on in-situ H-1 NMR kinetic studies. (C) 2015 Elsevier B.V. All rights reserved.