A new general and efficient synthesis of imidazo[4,5-c]pyrazoles (5) is reported. The key step of this synthetic procedure is the intramolecular cyclodehydration of 5-alkylamino-4-nitrosopyrazoles (4), which affords the title compounds (5) in good yields.
Highly Regioselective One-Pot, Three-Component Synthesis of 1-Aryl-3,4-Substituted/Annulated-5-(Cycloamino)/(Alkylamino)pyrazoles from β-Oxodithioesters
作者:Ganesh C. Nandi、Maya S. Singh、Hiriyakkanavar Ila、Hiriyakkanavar Junjappa
DOI:10.1002/ejoc.201101397
日期:2012.2
An efficient, highlyregioselective protocol for the synthesis of the title compounds is reported. The reaction involves a one-pot, three-component cyclocondensation of β-oxodithioester, amine, and hydrazine in ethanol at reflux in the presence of a catalytic amount of acetic acid. Densely functionalized pyrazoles were constructed through the cyclization of a thioamide intermediate generated in situ