S. AmarasekaraAnanda, PathmasiriW. Wimal
Feb 1, 2000
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Journal
Bulletin of the Chemical Society of Japan
Abstract
Maleimides react with 2-furaldehyde phenylhydrazone 1 at the furan ring to give 4-(phenylhydrazono)methyl-1H-isoindole-1,3(2H)-diones when equimolar mixtures are refluxed in benzene for shorter reaction times. Excess maleimides and longer reaction times give mixtures of 4-(phenylhydrazono)methyl-1H-isoindole-1,3(2H)-diones and 3-(1,3-dihydro-1,3-dioxo-4-isoindolyl)-1,6a-dihydropyrrolo[3,4-c]pyrazolo-4,6(3aH,5H)-diones resulting from [4+2] and [3+2] double-cycloaddition. Reactions of 1 with dimethyl acetylene dicarboxylate give the double-cycloaddition product dimethyl-3[4-hydroxy-2,3-bis(methoxycarbonyl)phenyl]-1-phenylpyrazole-4,5-dicarboxylate. Methyl acrylate and acrylonitrile gives only the [3+2] cycloaddition products, 3-(2-furyl)-1-phenyl-4,5-dihydropyrazole-4-carboxylic methyl ester and 3-(2-furyl)-1-phenyl-4,5-dihydropyrazole-4-carbonitrile, respectively.