Synthesis and spectroscopic characterizations of both 1-ethyl-4,8-dihydro-10-methoxy-3-methyl-8-r1-6-r2-dipyrazolo[3,4-b:4′,3′-f]-[1,5]diazocin-5(1H)-ones and 1-ethyl-1,4,8,9-tetrahydro-3,9-dimethyl-8-r1-6-r2-dipyrazolo[3,4-b:4′,3′-f][1,5]diazocine-5,10-diones of pharmaceutical interest

The non-selective methylation of compounds 3a-d using ethereal diazomethane, allowed the synthesis of isomers 4 and 5 which were useful intermediates for the preparation, by a simple approach, of the title compounds 7 and 9. A complete assignment of the chemical shifts to the carbon atoms of the compounds 7 and 9 was performed by different nmr experiments, such as DEPT and XHDEPT for onebond CH correlations and COLOC experiments for long-range C-H correlations.