Mild and efficient synthesis and base-promoted rearrangement of novel isoxazolo[4,5-]pyridines.

An efficient method for the synthesis of isoxazolo[4,5-]pyridines has been developed on the basis of readily available 2-chloro-3-nitropyridines via the intramolecular nucleophilic substitution of the nitro group as a key step. The previously unknown base-promoted Boulton-Katritzky rearrangement of isoxazolo[4,5-]pyridine-3-carbaldehyde arylhydrazones into 3-hydroxy-2-(2-aryl[1,2,3]triazol-4-yl)pyridines was observed.

Recent Developments in the Synthesis of HIV-1 Integrase Strand Transfer Inhibitors Incorporating Pyridine Moiety.

Human immunodeficiency virus (HIV) causes one of the most dangerous diseases-acquired immunodeficiency syndrome (AIDS). An estimated about 40 million people are currently living with HIV worldwide, most of whom are already on antiretroviral therapy. This makes the development of effective drugs to combat this virus very relevant.

Straightforward and Efficient Protocol for the Synthesis of Pyrazolo [4,3-]pyridines and Indazoles.

An efficient method for the synthesis of pyrazolo [4,3-]pyridines has been developed on the basis of readily available 2-chloro-3-nitropyridines via a sequence of SNAr and modified Japp-Klingemann reactions. The method offers a number of advantages including utilization of stable arenediazonium tosylates, operational simplicity as well as combining the azo-coupling, deacylation and pyrazole ring annulation steps in a one-pot manner. An unusual rearrangement (C-N-migration of the acetyl group) was observed and a plausible mechanism was proposed based on the isolated intermediates and NMR experiments.

Nucleophilic Functionalization of 2-R-3-Nitropyridines as a Versatile Approach to Novel Fluorescent Molecules.

A number of new 2-methyl- and 2-arylvinyl-3-nitropyridines were synthesized and their reactions with thiols were studied. It was found that 3-NO tends to be selectively substituted under the action of sulfur nucleophiles in the presence of another nucleofuge in position 5. Correlations between the substitution pattern and regioselectivity as well as photophysical properties were established.

Recent Progress in the Synthesis of Drugs and Bioactive Molecules Incorporating Nitro(het)arene Core.

Aromatic nitro compounds play a unique role in the synthesis of drugs and pharmaceutically oriented molecules. This field of organic chemistry continues to be in demand and relevant. A significant number of papers are published annually on new general methods for the synthesis of nitrodrugs and related biomolecules.

Nitropyridines as 2π-Partners in 1,3-Dipolar Cycloadditions with N-Methyl Azomethine Ylide: An Easy Access to Condensed Pyrrolines.

1,3-Dipolar cycloaddition reactions of 2-substituted 5--3-nitropyridines and isomeric 3--5-nitropyridines with N-methyl azomethine ylide were studied. The effect of the substituent at positions 2 and 5 of the pyridine ring on the possibility of the [3+2]-cycloaddition process was revealed. A number of new derivatives of pyrroline and pyrrolidine condensed with a pyridine ring were synthesized.

Synthesis and Facile Dearomatization of Highly Electrophilic Nitroisoxazolo[4,3-]pyridines.

A number of novel 6-R-isoxazolo[4,3-]pyridines were synthesized and their reactions with neutral C-nucleophiles (1,3-dicarbonyl compounds, π-excessive (het)arenes, dienes) were studied. The reaction rate was found to be dependent on the nature of the substituent 6-R. The most reactive 6-nitroisoxazolo[4,3-]pyridines are able to add C-nucleophiles in the absence of a base under mild conditions.

Nucleophilic dearomatization of 4-aza-6-nitrobenzofuroxan by CH acids in the synthesis of pharmacology-oriented compounds.

4-Aza-6-nitrobenzofuroxan (ANBF) reacts with 1,3-dicarbonyl compounds and other CH acids to give carbon-bonded 1,4-adducts - 1,4-dihydropyridines fused with furoxan ring. In the case of most acidic β-diketones, which exist mainly in the enol form in polar solvents, the reactions proceed in the absence of any added base emphasizing the highly electrophilic character of ANBF. The resulting compounds combine in one molecule NO-donor furoxan ring along with a pharmacologically important 1,4-dihydropyridine fragment and therefore can be considered as prospective platforms for the design of pharmacology-oriented heterocyclic systems.

[Nitrobenzofuroxane derivatives as dual action hiv-1 inhibitors].

Human immunodeficiency virus first type (HIV-1) is a main cause of one of the most dangerous diseases, AIDS. The search for new inhibitors of the virus still remains an urgent task. One approach to suppress the HIV infection is to use a double-acting inhibitors, i.

Structural-Functional Analysis of 2,1,3-Benzoxadiazoles and Their N-oxides As HIV-1 Integrase Inhibitors.

Human immunodeficiency virus type 1 integrase is one of the most attractive targets for the development of anti-HIV-1 inhibitors. The capacity of a series of 2,1,3-benzoxadiazoles (benzofurazans) and their N-oxides (benzofuroxans) selected using the PASS software to inhibit the catalytic activity of HIV-1 integrase was studied in the present work. Only the nitro-derivatives of these compounds were found to display inhibitory activity.

The versatile electrophilic reactivity of 4,6-dinitrobenzo[d]isoxazole-3-carbonitrile.

The interaction of 4,6-dinitrobenzo[d]isoxazole-3-carbonitrile (5a) with methoxide ion has been kinetically investigated in methanol and a 20:80 (v/v) MeOH-Me2SO mixture. In methanol, stopped-flow experiments have revealed that a monomethoxyl sigma-adduct (5a-Me) is first formed, resulting from a fast MeO- addition at the unsubstituted 7-carbon. Rate and equilibrium constants for this sigma-complexation process could be determined, allowing a ranking of 5a within the pKa scale established for Meisenheimer electrophiles in methanol.