95884-18-7Relevant academic research and scientific papers
Reactions of Glyoxals with Hydrazones: A New Route to 4-Hydroxypyrazoles
Begtrup, Mikael,Nytoft, Hans Peter
, p. 81 - 86 (2007/10/02)
N-Substituated hyrazones of aldehydes react with glyoxals under non-aqueous conditions to give N-substituted 4-hydroxypyrazoles; fourteen such products are described.In the presence of water, N-substituted 3-acyl-4-hydroxypyrazoles are produced from 2-oxoaldehyde hydrazones and glyoxals.It is shown that glyoxals combine in a 1:1 ratio with N-monosubstituted hydrazones to give 2-hydrazonoaldehydes as the kinetically controlled products.At room temperature or lower, these hydrazonoaldehydes rearrange to the more stable 2-oxoaldehyde hydrazones and react with glyoxals to give N-substituted 3-acyl-4-hydroxypyrazoles; sixteen such products are described.This synthesis, involving easily accessible starting materials, opens up a new, and for certain derivatives exclusive, route to 4-hydroxypyrazoles.
