Advances in the synthesis of benzimidazolones via rearrangements of benzodiazepinones and quinoxalin(on)es

Crystal structure, Hirshfeld surface analysis and inter-action energy calculation of 1-decyl-2,3-di-hydro-1H-benzimidazol-2-one

The title mol-ecule, C17H26N2O, adopts an L-shaped conformation, with the straight n-decyl chain positioned nearly perpendicular to the di-hydro-benzimidazole moiety. The di-hydro-benzimidazole portion is not quite planar as there is a dihedral angle of 1.20 (6)° between the constituent planes. In the crystal, N-H⋯O hydrogen bonds form inversion dimers, which are connected into the three-dimensional structure by C-H⋯O hydrogen bonds and C-H⋯π(ring) inter-actions. Hirshfeld surface analysis indicates that the most important contributions for the crystal packing are from H⋯H (75.9%), H⋯C/C⋯H (12.5%) and H⋯O/O⋯H (7.0%) inter-actions. Based on computational chemistry using the CE-B3LYP/6-31 G(d,p) energy model, C-H⋯O hydrogen bond energies are -74.9 (for N-H⋯O) and -42.7 (for C-H⋯O) kJ mol-1.

2,3-(Dibenzimidazol-2-yl)quinoxalines: Unexpected Dynamical Effect on Steady-State Electronic Absorption Spectra

We report on the electronic absorption spectra, conformational behavior, and intra- and intermolecular hydrogen bonds of 2,3-(dibenzimidazol-2-yl)-quinoxaline (DBIQ). The experimentally found strong solvent dependence of the absorption spectra of DBIQ solutions cannot be assigned to electronic excitations of the equilibrium ground-state DBIQ structure. Extended consideration including the nonequilibrium structures within the framework of ab initio molecular dynamics (MD) revealed the importance of torsion molecular motions not covered by the static case. The strong impact of solute-solvent hydrogen bonding on stabilization of these nonequilibrium structures and on conformational composition of DBIQ was demonstrated. A presence of twisted nonplanar geometries along the whole MD trajectory was shown to drastically influence not only energies but also characters of electronic excitations, resulting in a change of local π-π* character in a solution of 1,2-dichloroethane to charge-transfer character in polar dimethylsulfoxide.

Optimisation by Design of Experiment of Benzimidazol-2-One Synthesis under Flow Conditions

A novel flow-based approach for the preparation of benzimidazol-2-one (1) scaffold by the 1,1′-carbonyldiimidazole (CDI)-promoted cyclocarbonylation of o-phenylenediamine (2) is reported. Starting from a preliminary batch screening, the model reaction was successfully translated under flow conditions and optimised by means of design of experiment (DoE). The method allowed the efficient preparation of this privileged scaffold and to set up a general protocol for the multigram-scale preparation in high yield, purity, and productivity, and was successfully applied for the multigram flow synthesis of N-(2-chlorobenzyl)-5-cyano-benzimidazol-2-one, which is a key synthon for hit-to-lead explorations in our anti-inflammatory drug discovery program.

Multi-targeted approach by 2-benzimidazolylquinoxalines-loaded cationic arginine liposomes against сervical cancer cells in vitro

Multi-targeted approaches for inhibition of сervical cancer cells in vitro were developed by implementing two different strategies and drug combination for creation of new therapeutic target agents and for nanotechnological-enhancement of intracellular delivery. New 2-benzimidazolylquinoxalines derivatives were synthesized and characterized by combining two different pharmacophores - benzimidazole and quinoxaline rings directly bonded in their structures. Spectrophotometric technique for determination of content of compounds in various media was developed to evaluate their solubility in water and micellar solutions of surfactants. The bioavailability of poorly water-soluble 2-benzimidazolylquinoxalines was improved by PEGylated liposomes as antitumor drug delivery carriers. 2-benzimidazolylquinoxalines-loaded PEGylated liposomes, with size close to 100 nm and negative zeta potential ranging from -13 mV to -27 mV, were time-stable at room temperature. The design of liposomal formulations for improving cellular uptake and in vitro antitumor efficacy was performed by modification of liposome surface with the new arginine surfactant. The cell viability of 2-benzimidazolylquinoxalines-loaded arginine liposomes on human cancer M-Hela cells was 16% at the concentration 0.15 mg/ml. Moreover, these liposomes showed a lower toxicity (40%) against normal human Gang liver cells both at the lowest and highest tested concentrations.