A series of 2-methoxyphenyl-9-dialkylaminoethyl derivatives of imidazo[1,2-a]benzimidazole have been synthesized and their pharmacological properties have been studied. Some of the synthesized compounds exhibit antioxidant, radioprotector, antiarrythmic, spasmolytic, antiaggregant, anticalmodulin, and antisecretory properties. Some substances exhibit the properties of phosphodiesterase inhibitors, decrease calcium ion transport through membranes, increase myocardium resistance to hypoxia, and reduce the arterial pressure. The obtained data show good prospects for the synthesis and screening of biologically active substances in this chemical group.Imidazo[1,2-a]benzimidazole contains a guanidine pharmacophore and is a very promising system in the search for new biologically active compounds [1 -8]. In continuation of the previous investigations, we have synthesized a series of new derivatives of 2-phenylimidazo[1,2-a]-benzimidazole containing one or two methoxy groups in various positions of the phenyl ring. The aim of this study was to determine the effect of these substituents on the manifestations of some particular types of biological activity.2-Methoxyphenyl-substituted 9-dialkylaminoethylimidazo[1,2-a]benzimidazoles (VIII -XII) were synthesized using a somewhat modified standard scheme described previously [1,9], proceeding from 1-dialkylaminoethyl-2-aminobenzimidazoles (Ia -Id) and methoxy-substituted phenacylbromides (IIa -IIe).The process of quaternization of the initial amines I was previously carried out in ethanol. However, the high solubility of the target quaternary salts in this medium complicated isolation of the target components and made necessary their conversion into less soluble hydrobromides, which was achieved by adding HBr. In this study, the reactions were performed in aprotic solvents (acetone or acetonitrile), which led to the precipitation of bromides III -VII from the reaction mixtures with good yields. The only exception is the case of 2,5-dimethoxyphenacylbromides VII, which are readily soluble in acetone.Ia -Id; IIa -IId; III -VII; VIII -XII; XIIIa, XIIIb I, III -XII: R = Net 2 (a), N(CH 2 ) 5 (b), N(CH 2 CH 2 ) 2 O (c), NMe 2 (d); IIa, III, VIII: R 1 = 4-OCH 3 , R 2 = H; IIb, IV, IX: R 1 = 3-OCH 3 , R 2 = H; IIc, V, X: R 1 = R 2 = 3,4-(OCH 3 ) 2 ; IId, VI, XI: R 1 = R 2 = 2,4-(OCH 3 ) 2 ; IIe, VII, XII: R 1 = R 2 = 2,5-(OCH 3 ) 2 ; XIII: R = NEt 2 (a), N(CH 2 ) 5 (b).Compounds III -VII crystallize in the form of 2-aminobenzimidazolium salts. This is confirmed by the IR spectra, where two absorption bands due to stretching vibrations of the primary amino groups are observed at 3100 -3350 cm -1 and the characteristic absorption bands of carbonyl groups are found at 1680 -1700 cm -1 (Table 1). 476 0091-150X/05/3909-0476
