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Letters in Organic Chemistry
ISSN (Print): 1570-1786
ISSN (Online): 1875-6255
VOLUME: 11
ISSUE: 5
DOI: 10.2174/1570178610666131212231709      Price:  $58









Silica Supported Zr(HSO4)4 Catalyzed Solvent-free Synthesis of [1]Benzopyrano[ 4,3-b][1]benzopyran-6-ones and Xanthenones

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Author(s): Shahrzad Abdolmohammadi
Pages 350-355 (6)
Abstract:
A clean and efficient procedure is described for the synthesis of 7-(4-hydroxy-2-oxo-2H-1-benzopyran-3-yl)- 6H,7H-[1]benzopyrano[4,3-b][1]benzopyran-6-ones and 2-(2,3,4,9-tetrahydro-3,3-dimethyl-1-oxo-1H-xanthen-9-yl)-3- hydroxy-5,5-dimethyl-2-cyclohexen-1-ones from a quasi-Knoevenagel-Michael reaction sequence of salicylaldehydes with compounds having active methylene groups [4-hydroxycoumarin (4-hydroxy-2H-1-benzopyran-2-one) and dimedone (5,5-dimethyl-1,3-cyclohexanedione)] in a ratio of 1:2, in the presence of a catalytic amount of 60% Zr(HSO4)4/SiO2 as an efficient heterogeneous catalyst at 60 °C and under solvent-free conditions.
Keywords:
[1] Benzopyrano[4, 3-b] [1]benzopyran-6-ones, Quasi-Knoevenagel-Michael reaction sequence, silica supported Zr(HSO4)4, solvent-free conditions, xanthenones.
Affiliation:
Department of Chemistry, Faculty of Science, East Tehran Branch, Islamic Azad University, PO Box 33955-163, Tehran, Iran.