Solvent-free microwave synthesis of bis-pyrazolo[3,4-b : 4 ',3 '-e]-pyridines and study of their antifungal properties

The synthesis of a series of bis-pyrazolo[3,4-b:4',3'-e]pyridines (3) in the reaction of 5-amino-3-methyl-1-phenylpyrazole (1) with aldehydes (2) under microwave irradiation and solvent-free conditions is described. The structure elucidation of the products is based on detailed nmr analysis of experiments such as I H-COSY, NOESY, DEPT, HSQC and HMBC. These compounds showed moderate antifungal in vitro activity against dermatophytes.