One‐Pot Synthesis of Aryl Pyrazole C‐Nucleoside Analogs of Pyrazofurin from Sugar Alkynes

The naturally occurring Pyrazofurin possesses a broad spectrum of marked antitumor and antiviral activities. The aryl pyrazole C-nucleoside analogs of Pyrazofurin have been synthesized in good to excellent yields by one-pot coupling of sugar alkynes, acid chlorides and hydrazine hydrate at rt. The method is general, mild, and efficient and sixty-two examples have been given. The sugar alkynes include acyclic glycosides, furanosides, and pyranosides with free hydroxyl groups, various protecting groups such as benzyl groups, methyl groups, sensitive isopropylidene and sterically bulky triphenylmethyl substituents. The acid chlorides contain electron-donating, electron-neutral and electron-withdrawing groups.