An effective and convenient protocol has been developed for the conversion of D-glucose and 6-O-α-D-glucopyranosyl-D-fructose (palatinose®, isomaltulose) into 5-[(1'S)-1','2/-dihydroxyethyl]-1-phenylpyrazole-3-carboxaldehyde (4) and 5-[(1'S)-2-(α-D-glucopyranosyloxy)-1-hydroxethyl])-1-phenylpyrazole-3 -carboxaldehyde (5), key steps being the acetic anhydride-promoted dehydrative cyclization of the respective phenylosazones, and subsequent liberation of the N-acetylphenylhydrazone-blocked aldehyde function. Exploitation of the ensuing chemistry of 4 and 5 led to a variety of pyrazole building blocks with a diverse level of hydrophilic substituents (hydroxymethyl, dihydroxyethyl or glucosyl residues) and useful functional groups, such as chloro, cyano, aminomethyl, vinyl and acryloyl moieties.
Oikawa, N., Müller, C., Kunz, M., & Lichtenthaler, F. W. (1998). Hydrophilically functionalized pyrazoles from sugars. Carbohydrate Research, 309(3), 269–279. https://doi.org/10.1016/S0008-6215(98)00137-2