were obtained from the reaction of primary nitro compounds [methyl nitroacetate, 2-nitro-1-phenylethanone, (nitromethyl)benzene, 1-nitropropane, and (phenylsulfonyl)nitromethane] with dipolarophiles in refluxing mesitylene in the presence of a small amount of p-toluenesulfonic acid. The formation of these products can be explained in terms of 1,3-dipolar cycloaddition of nitrileoxide generated by a
gel-supported sodium hydrogen sulfate (NaHSO4/SiO2) or Amberlyst 15 as solid acid catalyst, and then the corresponding 3-acylisoxaszoles were obtained by reacting with alkynes via the 1,3-dipolar [3+2] cycloaddition. These heterogeneous catalysts are easily separable from the reaction mixture and reused. This synthetic method provides a facile, efficient, and reusable production of 3-acylisoxazoles.
Application of silica gel-supported polyphosphoric acid (PPA/SiO2) as a reusable solid acid catalyst to the synthesis of 3-benzoylisoxazoles and isoxazolines
3-Benzoylisoxazoles were synthesized by the reaction of alkynes and benzoylnitromethane using silica gel-supported polyphosphoric acid (PPA/SiO2). This reaction provides a convenient, efficient, and reusable synthetic method of isoxazole derivatives. (C) 2011 Elsevier Ltd. All rights reserved.
Synthesis of pyrrolo[2,1-a]isoquinolines from activated acetylenes, benzoylnitromethanes, and isoquinoline
作者:Issa Yavari、Mohammad Piltan、Loghman Moradi
DOI:10.1016/j.tet.2009.01.001
日期:2009.3
Isoquinoline reacts smoothly with aroylnitromethanes in the presence of dialkyl acetylenedicarboxylates and dibenzoylacetylene to produce pyrrolo[2,1,a]isoquinolines in good yields. Quinoline and benzothiazole also react in a similar way. Pyridine and N-methylimidazole catalyze the reaction between nitromethane derivatives with electron-deficient acetylenes to produce highly functionalized isoxazoles. (C) 2009 Elsevier Ltd. All rights reserved.