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Synthesis of 2-(2-hydroxy-3-amino)propyl derivatives of 4-alkoxy-6-methyl-1H-pyrrolo[3,4-c]pyridine-1,3(2H)-diones (24-35) is described. The chlorides used in the above synthesis exist mainly in the cyclic forms (18, 20-23). Only chloride with benzhydryl substituent at the nitrogen atom of piperazine has the chain structure (19). Among the studied imides the most active analgesics in the "writhing" syndrome test proved to be compounds 30 and 31 (with LD50 > 2000 mg/kg) containing 4-benzylpiperidino group. Furthermore, all imides suppressed significantly spontaneous locomotor activity of mice.

A UV spectrophotometric analysis of 4-methoxy-2-(3 (4-phenyl-1-piperazinyl)) propyl-2,3-dihydro-6-methyl-1,3-dioxo-1H-pyrrolo [3,4-c] pyridine (II) in HCI (0.01 mole/L) was performed by determining the values of specific absorption coefficients at the following analytical wavelengths: 225, 285 and 350 nm. The separation by means of TLC of compound II and of its five decomposition products was also studied. Silica gel coated plates (60 F254) were used and the mobile phase consisted of butanol--acetic acid--water. A validated RP-HPLC method for the determination or purity evaluation of II, with phenacetin as an internal standard, is described. The solution of II in HCI (0.01 mole/L) was chromatographed on an octadecyl column (LiChrosorb 100 RP-18 column 250 x 4.0 mm I.D., dp = 5 microm) using an eluent composed of the mixture acetonitrile--phosphate buffer pH = 2. Ultraviolet detection was used at an operation wavelength of 239 nm. The HPLC method was validated by determination of the following parameters: selectivity, precision, accuracy, linearity, stability of the analite, LOD and LOQ. Kinetic studies of the decomposition process of II in both acidic and alkaline environments demonstrated the instability of the imide group.