Synthesis, evaluation and structure-activity relationships of 5-alkyl-2,3-dihydroimidazo[1,2-c]quinazoline, 2,3-dihydroimidazo[1,2-c]quinazolin-5(6H)-thiones and their oxo-analogues as new potential bronchodilators was written by Bahekar, Rajesh H.;Rao, A. Raghu Ram. And the article was included in Arzneimittel-Forschung in 2001.Computed Properties of C7H4Br2N2 This article mentions the following:
With an aim to obtain potent bronchodilators, 2 series of 5-alkyl-2,3-dihydroimidazo[1,2-c]quinazolines (Va-1), 2,3-dihydroimidazo[1,2-c]quinazolin-5-(6H)-thiones (VIIIa-d) and their oxo-analogs (IXa-d) were designed. The compounds Va-1 were synthesized by two alternative routes. The former (Method A) based on the dehydrocyclization of 4-(1-hydroxyethyl)aminoquinazoline (IV) and the latter (Method B) involves the usage of 2-aminobenzonitrile (VI) which on reaction with ethylenediamine leads to the formation of the key intermediate 2-(2-aminophenyl)-4,5-dihydro-1H-imidazoles (VII). Finally the intermediate VII on condensation with different acid anhydrides yielded the title compound V. In general, method-A resulted the compound V in quantatively higher yields. 2,3-Dihydroimidazo[1,2-c]quinazolin-5 (6H)-thiones (VIII) were obtained by condensing VIi with carbon disulfide and a further oxidation of VIII gave their corresponding oxo-analogs (IX). The title compounds V, VIII and IX were evaluated for their bronchodilator activity using in vitro and in vivo (standard animal models) methods. All the test compounds exhibited bronchodilator activity. The structure activity relationship studies indicated good correlation between the nature of the substituent and bronchodilator activity. In the 5-alkyl substituted compounds V, a longer alkyl chain showed higher bronchodilator activity. Compounds VIII and IX were less potent and replacement of sulfur with oxygen showed no significant effect on the biol. activity. The presence of halogens altered the biol. activity in both the series. Among the compounds tested, 9-iodo-5-(propyl)-2,3-dihydroimidazo[1,2-c]quinazoline (VI) was the most potent (percentage protection = 87.1%; relative activity = 1.1 compared to the standard aminophylline). In the experiment, the researchers used many compounds, for example, 2-Amino-3,5-dibromobenzonitrile (cas: 68385-95-5Computed Properties of C7H4Br2N2).
2-Amino-3,5-dibromobenzonitrile (cas: 68385-95-5) belongs to nitriles. The electronic structure of nitriles is very similar to that of an alkyne with the main difference being the presence of a set of lone pair electrons on the nitrogen. In conventional organic reductions, nitrile is reduced by treatment with lithium aluminium hydride to the amine. Reduction to the imine followed by hydrolysis to the aldehyde takes place in the Stephen aldehyde synthesis, which uses stannous chloride in acid.Computed Properties of C7H4Br2N2
Referemce:
Nitrile – Wikipedia,
Nitriles – Chemistry LibreTexts