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Pyrazolo[5,1-b]quinazolinones were synthesized by consecutive pyrazole and quinazolinone ring closures in a new catalyst-free microwave-promoted domino reaction of hydrazine with 2-cyano-3-(methylthio)-3-(2-methoxycarbonylphenylamino)acrylates, which were prepared from methyl anthranilate and 2-cyano-3,3-bis(methylthio)acrylates. When… Click to show full abstract
Pyrazolo[5,1-b]quinazolinones were synthesized by consecutive pyrazole and quinazolinone ring closures in a new catalyst-free microwave-promoted domino reaction of hydrazine with 2-cyano-3-(methylthio)-3-(2-methoxycarbonylphenylamino)acrylates, which were prepared from methyl anthranilate and 2-cyano-3,3-bis(methylthio)acrylates. When 2-cyano-3,3-bis(methylthio)acrylates reacted directly with anthranilic acid hydrazide, the arylamino group remained intact, while hydrazide moiety transformed into 1-acylpyrazoles and further to (1,3,4-oxadiazolidene)-2-cyanoacetates. The structures of representatives from each group of the prepared heterocyclic compounds were examined in detail by X-ray crystallography.
Journal Title: Synthesis
Year Published: 2023
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