Schiff bases 2-7 obtained from 2-aminobenzimidazole (1) with 2,3-dimethoxy-, 3,4-dimethoxy-, 4-methoxy-, 4-chloro-, 4-bromo- and 2-bromobenzaldehyde. A series of pyrimido[1,2-a]- benzimidazole and α-cyanocinnamic derivatives have been synthezied in the reactions of Schiff bases 2-7 with selected nitriles α-containing active methylene group: malononitrile 8-12, cyanoacetamide 13-16, benzoylacetonitrile 17-21, benzylonitrile 22-24, cyanoaceticmethyl ester 25-28 and cyanoacetic benzylamide 29 (Scheme 1). The structure 8-29 were confirmed by the results of elemental analysis and their IR, 1H-, 13C-NMR and MS spectra.

Ab initio geometry optimization calculations for three pairs 1H and 10H of possible products 10 and 10a, 17 and 17a, 24 and 24a was performed within the density functional theory (DFT). The computational study was performed using Gaussian 98 program. calculated energies for optimized structures are presented in Table 1. Energy differences ΔE suggest that 10, 17 and 24 are more propable products than corresponding structures 10a, 17a and 24a respectively.

The products 8-29 of various chemical structure were obtained, which are interest for biological studies or which can be substrates for further syntheses.

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1. Synthesis and antiproliferative activity in vitro of pyridodiazepine derivatives.
2. PRIMARY CYTOTOXICITY EVALUATION OF NEW HETEROCYCLIC SYSTEMS WITH PYRIDODIAZEPINE.
3. SYNTHESIS AND ANTIPROLIFERATIVE ACTIVITY IN VITRO OF NEW 2-AMINOBENZIMIDAZOLE DERIVATIVES. PART 3. REACTIONS OF 2-ARYLIDENE- AMINOBENZIMIDAZOLE WITH SELECTED 1,3-DIKETONES.