DIETHYL OXALATE AND ACETONE REACTION WITH SUBSEQUENT INTERACTION WITH SUBSTITUTED 7-AMINOINDOLES

Abstract

The study described in the article is a continuation of scientific research on the problem of finding convenient methods for the synthesis of nitrogen-containing heterocyclic compounds with biological activity. This article describes the synthesis of tricyclic nitrogen-containing substances based on the interaction of oxalic acid, acetone and sodium diethyl ether with subsequent introduction of 2,3-dimethyl- or 1,2,3-trimethyl-7-aminoindoles into the reaction system in the presence of acetic acid. The synthesis is carried out in two stages. Both stages are carried out under one-reactor synthesis conditions, where toluene is used as a solvent. So by condensation of acetone with diethyloxalate in the presence of sodium, followed by the action of 1,2,3-trimethyl-7-aminoindole in acetic acid, previously unknown ethyl ester (2Z)-4-oxo-2-[(1,2), 3-trimethyl-1H-indole-7-yl)amino]-2-pentanoic acid with a yield of 28%. Subsequently, the synthesized compound was subjected to acid cyclization (boiling in trifluoroacetic acid, 72 °С), as a result of which 1,2,3,6-tetramethyl-1H-pyrrolo[3,2-h]quinoline-8-carboxylic acid ethyl ester was obtained with a yield of 36%. In the case of the use of 2,3-dimethyl-7-aminoindole, unsubstituted in the first position, (2Z)-5,6-dimethyl-2-(2-oxopropylidene)-1,2-dihydro-3-pyrrolо[1,2,3-de]quinoxalin-3-one with a yield of 37%. Monitoring the progress of the reaction and the purity of the obtained compounds was carried out chromatographically. The structural features of the synthesized compounds were established using UV spectroscopy and 1H NMR spectrometry. In the experimental 1H NMR spectra, the signals of the proton-containing groups of ethyl esters of indolyl carboxylic and pyrroloquinoline of carboxylic acids, as well as pyr-rolo[1,2,3-de]quinoxaline, with comparable integral intensity values are found in the expected region.