Synthesis and spectroscopic characterizations of both 1-ethyl-4,8-dihydro-10-methoxy-3-methyl-8-r<sub>1</sub>-6-r<sub>2</sub>-dipyrazolo[3,4-<i>b</i>:4′,3′-<i>f</i>]-[1,5]diazocin-5(1<i>H</i>)-ones and 1-ethyl-1,4,8,9-tetrahydro-3,9-dimethyl-8-r<sub>1</sub>-6-r<sub>2</sub>-dipyrazolo[3,4-<i>b</i>:4′,3′-<i>f</i>][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