Microwave-assisted regioselective one-pot synthesis of trisubstituted pyridine scaffolds using K<sub>5</sub>CoW<sub>12</sub>O<sub>40</sub>.3H<sub>2</sub>O under solvent free conditions
作者:Srinivas Kantevari、Mahankhali Venu Chary、Srinivasu V. N. Vuppalapati、N. Lingaiah
DOI:10.1002/jhet.5570450424
日期:2008.7
A highly efficient, microwave-assisted, regioselectivesynthesis of 2,3-disubstituted-6-arylpyridines and new series of 7,7-dimethyl-2-aryl-5,6,7,8-tetrahydroquinoline-5-ones from enaminones in the presence of K5CoW12O40.3H2O (1.0 mol %) as heterogeneous catalyst undersolventfreeconditions is reported.
高效的微波辅助区域选择性合成的2,3-二取代的6-芳基吡啶和新的7,7-二甲基2-芳基5,6,7,8-四氢喹啉5-酮从氨基酮中合成。据报道在无溶剂条件下存在K 5 CoW 12 O 40 .3H 2 O(1.0 mol%)作为非均相催化剂。
Cu-Catalyzed Three-Component Cascade Annulation Reaction: An Entry to Functionalized Pyridines
A concise copper-catalyzed N-O bond cleavage/C-C/C-N bond formation procedure has been described for the synthesis of multisubstituted pyridines. Various oxime acetates, activated methylene compounds, and a wide range of aldehydes bearing aryl, heteroaryl, vinyl, and trifluoromethyl groups were employed to provide the tri- or tetrasubstituted pyridines with flexible substitution patterns. Moreover, this method features inexpensive catalysts, no need for extra oxidant, and high step-enconomy, which make it pratical and attractive.
A highly efficient regioselective one-pot synthesis of 2,3,6-trisubstituted pyridines and 2,7,7-trisubstituted tetrahydroquinolin-5-ones using K5CoW12O40·3H2O as a heterogeneous recyclable catalyst
A systematic investigation into the regioselective one-pot, three-component condensation of enaminones la-g, beta-dicarbonyl compounds 2a-c, and ammonium acetate in the presence of a catalytic amount of K5CoW12O40 center dot 3H(2)O (0.01 equiv or 1.0 mol %) under solvent free conditions, as well as in refluxing isopropanol, has been reported. The reaction was highly efficient to produce 2,3,6-trisubstituted pyridines 3a-g, 4a-g, and novel 2,7,7-trisubstituted-5,6,7,8-tetrahydroquinoline-5-ones 5a-g in excellent yields. The present procedure offers advantages of short reaction time, simple work-up, and the catalyst exhibited remarkable reusable activity. (c) 2007 Elsevier Ltd. All rights reserved.