Dorina Mantu

Synthesis and antituberculosis activity of some new pyridazine derivatives. Part II.

A series of eighteen novel compounds with pyridazine moiety were synthesized and their in vitro antituberculosis activities have been evaluated. A fast, general, and facile method for preparation of pyridazine derivatives in moderate to excellent yields is presented. Three compounds were found to be moderate active against Mycobacterium tuberculosis. Correlation of structure-biological activity has been done.

A facile synthesis of pyridazinone derivatives under ultrasonic irradiation.

A new, efficient and general method for preparation of N-substituted-pyridazinones using ultrasound irradiation is reported. Under ultrasound the reaction time decreases substantially, the yields are high and the reaction conditions are mild. It was noticed that substituents at the 3-(6)-position of pyridazone heterocycle have a substantial influence on the reactivity, while the effect of the substituents at the 1-(2)-position seems to be of minor importance. A comparative study of the reactions performed under ultrasound conditions versus at room temperature has been done.

Ultrasound and microwave assisted synthesis of isoindolo-1,2-diazine: A comparative study

A comparative study, ultrasound (US) versus microwave (MW) versus conventional thermal heating (TH), for synthesis of isoindolo-1,2-diazine is described. The reaction pathway is fast, efficient and straight applicable, involving a Huisgen [3+2] dipolar cycloaddition of cycloimmonium ylides to 1,4-naphthoquinone. A feasible reaction mechanism for the obtaining of the fully aromatized tetra- and penta- cyclic isoindolo-1,2-diazine is presented. Under US irradiation the yields are much higher (sometimes substantially, by almost double), the reaction time decreases substantially, the reaction conditions are milder. The use of a generator with a higher nominal power induces higher yields and short reaction times. Overall the use of US it proved to be more efficient than MW or TH. A feasible explication for US efficiency is presented.

Hybrid imidazole (benzimidazole)/pyridine (quinoline) derivatives and evaluation of their anticancer and antimycobacterial activity

Abstract The design, synthesis, structure, and in vitro anticancer and antimycobacterial activity of new hybrid imidazole (benzimidazole)/pyridine (quinoline) derivatives are described. The strategy adopted for synthesis is straight and efficient, involving a three-step setup procedure: N-acylation, N-alkylation, and quaternization of nitrogen heterocycle. The solubility in microbiological medium and anticancer and antimycobacterial activity of a selection of new synthesized compounds were evaluated. The hybrid derivatives have an excellent solubility in microbiological medium, which make them promising from the pharmacological properties point of view. One of the hybrid compounds, 9 (with a benzimidazole and 8-aminoquinoline skeleton), exhibits a very good and selective antitumor activity against Renal Cancer A498 and Breast Cancer MDA-MB-468. Moreover, the anticancer assay suggests that the hybrid Imz (Bimz)/2-AP (8-AQ) compounds present a specific affinity to Renal Cancer A498. Concerning the antimycobacterial activity, only the hybrid compound, 9, has a significant activity. SAR correlations have been performed.

Hybrid anticancer 1,2-diazine derivatives with multiple mechanism of action. Part 3 [4,5]

Antitumour chemotherapy is nowadays a very active field of research, DNA targeting drugs being the most widely used group in therapy. The design, synthesis and anticancer activity of a new class of anticancer derivatives with pyrrolo-1,2-diazine and benzoquinone skeleton is presented. The synthesis is direct and efficient, involving an alkylation followed by a [3+2] dipolar cycloaddition. The penta- and tetra-cyclic pyrrolo-1,2-diazine were evaluated for their in vitro anticancer activity against an NCI 60 human tumour cell line panel. The pentacyclic-1,2-diazine exhibit a significant anticancer activity against Non-Small Cell Lung Cancer NCI-H460, Leukemia MOLT-4, Leukemia CCRF-CEM and Breast Cancer MCF7. We hypothesize that these molecules will exert their anticancer activity through multiple mechanisms of action: intercalating the DNA, inhibiting the topoisomerase enzymes and, destroying the DNA strands via electron transfer mechanism. However, the intercalation with the DNA seems to prevail in competition with the others mechanisms.

Design, Synthesis and Antimycobacterial Activity of Some New Pyridazine Derivatives: Bis-pyridazine. Part IV 12-14

The design, synthesis, structure and the antimycobacterial activities of a new class of nitrogen heterocycles, namely N1-substituted-diphenyl ether-bis-pyridazine (BP), is presented. An efficient, facile and straight applicable method for preparation of BP derivatives is described. The primary cycle high throughput screening reveals that two BP compounds, 2a and 3b, are potent inhibitors against Mycobacterium tuberculosis (Mtb), with their antitubercular activity being superior to the second-line antitubercular drug Pyrimethamine and being equal to Cycloserine. The data from cycle-2 screening confirm the results from cycle-1. The MIC, MBC, LORA, intracellular (macrophage) drug screening, and MTT cell proliferation, indicate the intracellular drug effectiveness against Mtb of these compounds, the lack of toxicity, a significant activity against both replicating and non-replicating Mtb and, a bactericidal mechanism of action (for 2b). SAR correlations have been done. Overall, the BP derivatives and especially compound 2b, appeared as a new leading antitubercular structure, which makes it a promising lead for further drug development.

NMR and X-ray Studies Concerning Structure of 6,6'-(Oxybis(4,1-phenylene))bis-(2-allylpyridazin- 3(2H)-one)

Abstract The structural NMR and X-ray studies of 6,6’-(Oxybis(4,1- phenylene))bis-(2-allylpyridazin-3(2H)-one), a bis-pyridazine derivative heterocycle, are reported in this study. Both 1H- and 13C- NMR confirm the proposed structure of compound. In order to establish unequivocally the structure of compound, the X-ray data analysis was performed. The compound crystallizes in the triclinic P-1(2) space group with a = 10.3699(7) Å, b = 10.6972(6) Å, c = 11.0449(4) Å, α = 87.941(5)°, β = 75.564(5)°, γ = 72.055(5)°, V= 1127.68 (12) Å3 and Z = 2. Molecular and crystal packing parameters for the novel heterocyclic system were obtained from intensity data collected at room temperature. The two phenyl rings (from the diphenyl ether moiety) are perpendicular one to each other and, on its turn, each phenyl ring is almost coplanar with the pyridazine ring

The Cycloaddition of the Benzimidazolium Ylides with Alkynes: New Mechanistic Insights.

New insights concerning the reaction mechanism in the cycloaddition reaction of benzimidazolium ylides to activated alkynes are presented. The proposed pathway leading both to 2-(1H-pyrrol-1-yl)anilines and to pyrrolo[1,2-a]quinoxalin-4(5H)-ones involves an opening of the imidazole ring from the cycloaddition product, followed by a nucleophilic attack of the aminic nitrogen to a proximal carbonyl group and the elimination of a leaving group. The mechanistic considerations are fully supported by experimental data, including the XRD resolved structure of the key reaction intermediate.