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

Naturally occurring pyrazofurin has a wide range of antitumor and antiviral activities. Aryl pyrazole C-nucleoside analogs of pyrazofurin have been synthesized in good to excellent yields by a one-pot coupling reaction of sugar alkynes, acid chlorides, and hydrazine hydrate at room temp. The method is general, mild, and efficient, and 62 examples are given. The sugar alkynes include acyclic sugars, furanosides, and pyranosides, with free hydroxyl groups, and various protecting groups, such as benzyl groups, methyl groups, sensitive isopropylidene groups, and sterically bulky triphenylmethyl substituents. The acid chlorides contain electron-donating, electron-neutral, and electron-withdrawing groups.