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. ... Tetrahedron Vol. 46, No. 16, pp. 5777-5788,1990 Printed in Great Britain 0040-4020^0 S3.00+.00 1990 Pergamon Press pic A NEW GENERAL AND EFFICIENT SYNTHESIS OF IMIDAZO[4,5-c]PYRAZOLE ...