Synthesis, antiviral activity and structure-activity relationship of 1-(1-aryl-4,5-dihydro-1H-imidazoline)-3-chlorosulfonylureas and products of their cyclization

Novel 1-(1-aryl-4,5dihydro-1H-imidazoline)-3-chlorosulfonylourea derivatives 3a-3f were synthesized in the reaction of 1-aryl-4,5-dihydro-1H-imidazol-2-amines with chlorosulfonyl isocyanate. The second series of compounds 4a-4f was prepared from the respective 1-(1-aryl-4,5-dihydro-1H-imidazoline)-3-chlorsulfonylureas 3a-3f and 1,1'-carbonyldiimidazole (CDI). The selected compounds were tested for their activity against Herpes simplex virus and coxsackievirus B3 (CVB3). It was determined that three derivatives, i.e 3d, 4a and 4d are active against Herpes simplex virus (HSV-1). Compounds 3d and 4c are active against CVB3. Their favorable activity can be primarily attributed to their low lipophilicity values. Moreover, the lack of substituent in the phenyl moiety or 4-methoxy substitution can be considered as the most beneficial for the antiviral activity.

Synthesis and antiviral activity of 1-(1,3-disubstitutedimidazolidyn-2-ylidene)-3-ethoxycarbonylmethylurea derivatives

Novel 1-(1,3-disubstituted-imidazolidyn-2-ylidene)-3-ethoxycarbonylmethylurea derivatives (3a-3j) were obtained from appropriate 1-aryl-3-arylsulfonyl-1H-imidazolidine-2-imines (1a-1j) and ethyl isocyanatoacetate (2), which were subjected to condensation. Seven compounds were tested for their antiviral activity against HSV-1 and CVB3 viruses. Among the tested compounds, 3c was found to be active against HSV-1, proving that 4-methoxy substituent as R and 4-methyl substituent as R1 are most beneficial for activity against this virus. Furthermore, 3e and 3g were active against CVB3, which demonstrated that both 4-methyl and 4-chloro substitution is tolerated as R1, whereas 4-chloro and 2-methoxy substituents are best as R. It was also shown that the active compounds are characterized by relatively big surface area, small ovality, and greatest HOMO and LUMO energies in comparison to the rest of the compounds.

Synthesis, central nervous system activity and structure-activity relationships of novel 1-(1-Alkyl-4-aryl-4,5-dihydro-1H-imidazo)-3-substituted urea derivatives

A series of 10 novel urea derivatives has been synthesized and evaluated for their central nervous system activity. Compounds 3a-3h were prepared in the reaction between the respective 1-alkyl-4-aryl-4,5-dihydro-1H-imidazol-2-amines 1a and 1b and appropriate benzyl-, phenethyl-isocyanate or ethyl 4-isocyanatobenzoate and ethyl isocyanatoacetate 2 in dichloromethane. Derivatives 4c and 4g resulted from the conversion of 3c and 3g into the respective amides due to action of an aqueous ammonia solution. The results obtained in this study, based on literature data suggest a possible involvement of serotonin system and/or the opioid system in the effects of tested compounds, and especially in the effect of compound 3h. The best activity of compound 3h may be primarily attributed to its favourable ADMET properties, i.e., higher lipophilicity (related to lower polar surface area and greater molecular surface, volume and mass than for other compounds) and good blood-brain permeation. This compound has also the greatest polarizability and ovality. The HOMO and LUMO energies do not seem to be directly related to activity.

Synthesis, central nervous system activity, and structure-activity relationship of 1-aryl-6-benzyl-7-hydroxy-2,3-dihydroimidazo[1,2-a]pyrimidine-5(1H)-ones

A series of 24 1-aryl-6-benzyl-7-hydroxy-2,3-dihydroimidazo[1,2-a]pyrimidine-5(1H)-ones was designed as antinociceptive compounds acting through opioid receptors with additional serotoninergic activity. The compounds, similarly as previously published series, lack the protonable nitrogen atom which is a part of classical opioid receptor pharmacophore and is necessary to interact with the conserved Asp(3.32) in the opioid receptor binding pocket. The compounds were obtained in one-step cyclocondensation of 1-aryl-4,5-dihydro-1H-imidazol-2-amines diethyl 2-benzylmalonate or diethyl 2-(2-chlorobenzyl)malonate under basic conditions. Almost all the tested compounds exerted strong antinociceptive activity, but surprisingly, it was not reversed by naloxone; thus, it is not mediated through opioid receptors. It makes it possible to conclude that addition of one more aromatic moiety to the non-classical opioid receptor pharmacophore results in the compounds which are not opioid receptor ligands. The lack of activity of one of the tested compounds may be attributed to low blood–brain barrier permeation or unfavorable distribution of electrostatic potential and HOMO and LUMO orbitals.

6-(2-Chloro-benz-yl)-1-(4-chloro-phen-yl)-7-hy-droxy-2,3-dihydro-1H-imidazo[1,2-a]pyrimidin-5-one

The title compound, C(19)H(15)Cl(2)N(3)O(2), was obtained by a one-step cyclo-condensation of 2-amino-1-(4-chloro-phen-yl)imidazoline with diethyl (2-chloro-benz-yl)malonate under basic conditions. In the crystalline state, the mol-ecule exists as the 7-hy-droxy-5-oxo tautomer. The dihedral angles between the fused imidazopyrimidine and aromatic chloro-phenyl and chloro-benzyl rings are 14.2 (1) and 70.7 (1)°, respectively. The conformation of the mol-ecule is influenced by the intra-molecular C-H⋯O and C-H⋯N hydrogen bonds, giving a nearly planar five-ring fused system [maximum deviation from the mean plane = 0.296 (2) Å]. In the crystal structure, strong inter-molecular O-H⋯O hydrogen bonds link the mol-ecules into chains along the c axis. These chains are further stabilized by weak C-H⋯Cl and π-π inter-actions [centroid-centroid distance = 3.6707 (12) Å].