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Title
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Reaction of ethyl 2-(arylidene)acetoacetates, 3-
methyl-1H-pyrazol-5(4H)-one, and ammonium acetate:
Unexpected formation of bis(pyrazolyl)methanes versus
fused pyrazolo-1,4-dihydropyridines
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Abstract
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The reaction of 3-methyl-1H-pyrazol-5(4H)-one, ethyl 2-(arylidene)acetoacetates,
and ammonium acetate in refluxing ethanol leads to the
formation of 4,4′-(arylmethylene)bis(3-methyl-1H-pyrazolyl-5-ol) derivatives
with high yields, instead of the expected fused
pyrazolo-1,4-dihydropyridines. This suggests the presence of a reactive
vinylogous imino derivative as an intermediate.
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