A. I. Bokanov

Pyrazolo[3,4-a]carbazoles: Synthesis, antibacterial and antifungal activity

Pyrazolo[3,4-a]carbazoles constitute a new class of heterocyclic compounds. We obtained the first representatives of this class the 7-R-4,5-dihydropyrazolo[3,4-a]carbazoles (I-VIII) from the corresponding ketocarbazoles (IX, X). Ketocarbazoles IX were condensed with dimethylformamide diethylacetal (XI) and the enamines (XII-XVI) obtained were converted into pyrazolocarbazoles I-V by the action of hydrazine hydrate in boiling ethanol.

Antiviral activity of 1-amino-1,2,3,4-tetrahydrocarbazoles

We have shown in the preceding paper [2] that l-aminotetrahydrocarbazo!es (I-XI) suppress the growth of tuberculosiss myobacteria in in vitro experiments. During more extensive biological studies of compounds I-XI we have found that compounds VIII-XI have an inhibiting action on the reproduction of the herpes virus. Therefore we have also synthesized the l-aminotetrahydrocarbazoles (XI!-XX) and studied their antiviral activity.

Antitubercular, antifungal, and antibacterial activity in vitro of 1-phenethylamino-1,2,3,4-tetrahydrocarbazoles

The biological activity of l-aminotetrahydrocarbazoles was discovered by in vitro experiments in [i, 6]. Of the compounds studied, the most active was 6-methyl-l-phenethylamino1,2,3,4-tetrahydrocarbazole (I). In order to find the relationship between the biological activity and the structure of the compounds, we studied the analogs of compound I: its homologs (II, III), the hydrogenated derivatives (IV, V), and also compounds with various substituents in the 6-position (VI-XI).

Synthesis of 1,6-Carbazoledicarboxylic and 1,2,3,4-Tetracarbazole-1,6-dicarboxylic Acid Esters

The class of derivatives of carbazolecarboxylic acids contains substances combining low toxicity with high antitumor activity [1]. It was found that the synthesis of some compounds of this class can be performed using 1,6-carbazoledicarboxylic acid diethyl ester as the initial reactant. However, methods for the synthesis of 1,6-carbazoledicarboxylic acid and its esters have not be developed. To the best of our knowledge, only one publication [2] points out that 1,6-carbazoledicarboxylic acid diethyl ester (I) can be obtained with a yield of 5% via photochemical oxidation of carbazole in an ethanol – carbon tetrachloride mixture.

Synthesis and pharmacological examination of hydrogenated 8-phenyl-1H-pyrazino-[3,2,1-jk]carbazoles

The pyrazinocarbazoie (IV) was synthesized as follows. Reaction of the diazobiphenyi (VI) with the formyicyciohexanone salt (VII) afforded the cyciohexanedione biphenyiyihydrazone (VIIi), which was then converted into the ketocarbazole (IX) by the Fischer method. The overall yield of the ketone (IX) (calculated on 4-aminobiphenyl) was 70%. Using a method similar to that used for pyrazidoi [i], the ketocarbazoie (IX) was converted via the iminocarbazoies (X) and (XI) into the required compound (IV). The overall yield of the pyrazinocarbazoie (IV) was 44%, calculated on the ketone (IX).

Synthesis of heterocycles on the basis of iminotetrahydrocarbazoles. 1. 3-Benzyl-8-methyl-2-oxo-2,3,3a,4,5,6-hexahydro-1H-pyrazino[3,2,1-j,k]-carbazole

The reaction of 6-methyl-1-oxo-1,2,3,4-tetrahydrocarbazole and benzylamine gave 1-benzylimino-6-methyl-1,2,3,4-tetrahydrocarbazole, which was converted by two methods to a pyrazinocarbazole derivative. The promising character of the use of iminotetrahydrocarbazoles for the synthesis of more complex heterocyclic systems was thereby demonstrated.