6-Aryl- and 6,7-diaryl-1,3-dimethyl-1-perimidin-2(3)-ones: synthesis, conformational stability, crystal structure and optical properties.

6-Bromo- and 6,7-dibromo-1,3-dimethyl-1-perimidin-2(3)-ones were arylated with arylboronic acids under Suzuki-Miyaura reaction conditions to afford 6-aryl-, 6-bromo-7-aryl- and 6,7-diaryl-1,3-dimethyl-1-perimidin-2(3)-ones. A comparison of the X-ray structural parameters of -diaryl derivatives of 1,3-dimethyl-1-perimidin-2(3)-one, naphthalene and 1,8-bis(dimethylamino)naphthalene (proton sponge) was performed. Based on the data of dynamic H NMR spectroscopy and quantum-chemical calculations, barriers to /-isomerization of 6,7-diaryl-1,3-dimethyl-1-perimidin-2(3)-ones were estimated.

Anion and Substituents Effect on Spectral-Kinetic and Biological Characteristics of Spiropyran Salts.

Spiropyran salts containing a cationic vinyl-3H-indolium moiety are characterized by NIR absorption and fluorescence of their merocyanine forms. This feature makes them promising fluorescent probes and markers for bioimaging. The article focuses on the synthesis and study of the spectral, kinetic and toxic characteristics of such compounds with respect to various substituents in different moieties and the type of anion.

Synthesis, electrochemical properties, and antioxidant activity of sterically hindered catechols with 1,3,4-oxadiazole, 1,2,4-triazole, thiazole or pyridine fragments.

A series of new RS-, RS-CH- and RN-CH-functionalized сatechols with heterocyclic fragments such as 1,3,4-oxadiazole, 1,2,4-triazole, thiazole, or pyridine were synthesized by the reaction of 3,5-di--butyl--benzoquinone or 3,5-di--butyl-6-methoxymethylcatechol with different heterocyclic thiols. The S-functionalized catechols were prepared by the Michael reaction from 3,5-di--butyl--benzoquinone and the corresponding thiols. The starting reagents such as substituted 1,3,4-oxadiazole-2-thiols and 4-triazole-3-thiols are characterized by thiol-thione tautomerism, therefore their reactions with 3,5-di--butyl-6-methoxymethylcatechol can proceed at the sulfur or nitrogen atom.

Proton Sponge Zwitterions with Positively and Negatively Charged Hydrogen Bonds: Extremely Polar Organic Compounds and Interplay of [NHN] and [NHN] Properties.

Six previously unknown zwitterions with positively and negatively charged [NHN] hydrogen bonds were synthesized by acylation of 4,5-bis(dimethylamino)-1-tosylamino-8-aminonaphthalene with subsequent alkaline treatment of the resulting 8-acylamino derivatives. Using NMR and XRD measurements in conjunction with quantum chemical DFT/PBE1PBE/6-311++G(d,p) calculations, it was shown that the negatively charged [NHN] bond in such compounds commonly differs from the [NHN] bond by significantly lower linearity, higher asymmetry, and moderate to strong paramagnetic shift of the chelated NH proton signal. Among other remarkable findings, the most important are (1) unusually high polarity (μ = 21-26 D) of the obtained zwitterions, (2) sharp difference in structures of the solid 1,8-bis(tosylated) zwitterion (BTZ) grown from MeCN or DMF, and (3) registration for one of the stereoisomers of BTZ with the record short [NHN] hydrogen bridge (N···N = 2.

Unveiling Orthogonal Reactivity of Substituted 2-(2-Azidostyryl)furans: Thermolysis and Photolysis versus Catalysis.

A systematic investigation of the decomposition of substituted 2-(2-azidostyryl)furans has been reported. The products of catalytic decomposition align with predictable patterns, consistent with established literature data. In contrast, photolysis and thermolysis lead to the formation of unexpected products.

Synthesis of photo- and ionochromic N-acylated 2-(aminomethylene)benzo[]thiophene-3(2)-ones with a terminal phenanthroline group.

A series of novel photo- and ionochromic N-acylated 2-(aminomethylene)benzo[]thiophene-3(2)-ones with a terminal phenanthroline receptor substituent was synthesized. Upon irradiation in acetonitrile or DMSO with light of 436 nm, they underwent - isomerization of the C=C bond, followed by very fast N→O migration of the acyl group and the formation of nonemissive O-acylated isomers. These isomers were isolated preparatively and fully characterized by IR, H, and C NMR spectroscopy as well as HRMS and XRD methods.

Substitution reactions in the acenaphthene analog of quino[7,8-]quinoline and an unusual synthesis of the corresponding acenaphthylenes by -elimination.

The possibility of functionalization of dipyrido[3,2-:2',3'-]acenaphthene containing a quino[7,8-]quinoline fragment and being a highly basic diazine analog of 1,8-bis(dimethylamino)naphthalene ("proton sponge") has been studied for the first time. In addition to the pronounced tendency of the title compound to form associates with an intramolecular hydrogen bond of the NHN type (new examples with the participation of pyridine rings, including self-associates are shown) and its inertness to amination reactions of the pyridine rings, the naphthalene core at positions 5(8) and the CHCH bridge (dehydrogenation) undergo chemical modifications under mild conditions, giving the corresponding acenaphthylenes. The latter can also be obtained in an unusual way by -elimination from 5,8-dibromodipyridoacenaphthene by reaction with neutral or anionic bases.

Divergent Transformations of 2-Nitro-1-benzo[]chromenes in Reactions with Alkylidenemalononitriles: Access to Naphtho[2,1-]furans via Base-Mediated Pyran Ring Contraction.

The action of 2-(1-arylethylidene)malononitriles on 2-nitro-1-benzo[]chromenes in the presence of EtN and MoO·2HO results in naphtho[2,1-]furans containing an allylidenemalononitrile unit in the α-position. The reaction proceeds with contraction of the pyran ring via a cascade carba-Michael addition/retro-oxa-Michael reaction/tautomerization/S2/oxidation process. In contrast, the reaction of 2-nitro-1-benzo[]chromenes with the cyclic Knoevenagel adduct derived from 1-indanone and malononitrile leads to dihydroindeno[1,2-]xanthenes.

Copper(II) coordination compounds based on bis-hydrazones of 2,6-diacetylpyridine: synthesis, structure, and cytotoxic activity.

By reacting a series of 2,6-diacetylpyridine bis-hydrazones containing pyrimidine (H2L1), benzimidazole (H2L2) and phthalazine (H2L3) heterocyclic fragments with copper(II) chloride and bromide, a variety of pentacoordinated complexes of the composition , and , where X = Cl, Br, are formed. The properties and structure of the compounds were studied by means of NMR, IR, UV-vis, ESR, and X-ray absorption spectroscopy, cyclic voltammetry and X-Ray single crystal diffraction methods. It was shown that complexes of the cationic type have an asymmetric structure with a distorted square-pyramidal geometry of the coordination unit.

Reaction of quinaldine with 4,6-di(-butyl)-3-nitro-1,2-benzoquinone. Dependence of the outcome on the reaction conditions and a deeper insight into the mechanism.

Condensation of quinaldine with 4,6-di (-butyl)-3-nitro-1,2-benzoquinone results in the formation of 5,7-di (-butyl)-2-(quinoline-2-yl)-1,3-tropolone, 5,7-di (-butyl)-4-nitro-2-(quinoline-2-yl)-1,3-tropolone, 3,3-dimethyl-2-(5-hydroxy-4-nitro-3--butyl-6-quinoline-2-yl-pyridine-2-yl)butanoic acid, 6-(2,2-dimethylprop-3-yl)-5--butyl-4-nitro-2-(quinoline-2-yl)-pyridine-3-ol, 1,7-di (-butyl)-3-(quinoline-2-yl)-2-azabicyclo-[3.3.0]octa-2,7-diene-4,6-dione--oxide.

Novel Indoline Spiropyrans Based on Human Hormones β-Estradiol and Estrone: Synthesis, Structure, Chromogenic and Cytotoxic Properties.

The introduction of a switchable function into the structure of a bioactive compound can endow it with unique capabilities for regulating biological activity under the influence of various types of external stimuli, which makes such hybrid compounds promising objects for photopharmacology, targeted drug delivery and bio-imaging. This work is devoted to the synthesis and study of new spirocyclic derivatives of important human hormones-β-estradiol and estrone-possessing a wide range of biological activities. The obtained hybrid compounds represent an indoline spiropyrans family, a widely known class of organic photochromic compounds.

Synthesis, conformational stability and molecular structure of 4-aryl- and 4,5-diaryl-1,8-bis(dimethylamino)naphthalenes.

4-Bromo- and 4,5-dibromo-1,8-bis(dimethylamino)naphthalenes were arylated with arylboronic acids under Suzuki reaction conditions to provide 4-aryl- and 4,5-diaryl-1,8-bis(dimethylamino)naphthalenes, respectively. The interaction of 4,5-dibromo-1,8-bis(dimethylamino)naphthalene with pyridin-3-ylboronic acid was accompanied by heterocyclization leading unexpectedly to the formation of ,,,-tetramethylacenaphtho[1,2-]pyridine-3,4-diamine. Dynamic H NMR experiments showed fast interconversion between and conformers of 4,5-diaryl-1,8-bis(dimethylamino)naphthalenes in CDCl solution at room temperature.

Organometallic Synthesis of 2,3,6,7-Tetrasubstituted 1,8-Bis(dimethylamino)naphthalenes for Investigation of the Double Buttressing Effect in Proton Sponges.

The lithiation of 2,7-disubstituted derivatives of 1,8-bis(dimethylamino)naphthalene (DMAN, proton sponge) bearing potentially -directing OMe, NMe, and SMe groups was studied. It has been shown that OMe groups facilitate selective dual β-lithiation of the naphthalene moiety while the 2(7)-NMe groups allow only monolithiation presumably due to the decreased acidity of the ring C-H bonds and conformational immobilization after coordination to the lithium atom. In contrast, the SMe groups provided no ring lithiation and underwent deprotonation of their methyl fragment.

SNH Amidation of 5-Nitroisoquinoline: Access to Nitro- and Nitroso Derivatives of Amides and Ureas on the Basis of Isoquinoline.

For the first time, amides and ureas based on both 5-nitroisoquinoline and 5-nitrosoisoquinoline were obtained by direct nucleophilic substitution of hydrogen in the 5-nitroisoquinoline molecule. In the case of urea and monosubstituted ureas, only 5-nitrosoisoquinoline-6-amine is formed under anhydrous conditions.

Catalyst-free formal [3 + 2] cycloaddition of stabilized ,-cyclic azomethine imines to 3-nitrobenzofurans and 3-nitro-4-chromenes: access to heteroannulated pyrazolo[1,2-]pyrazoles.

We have studied the [3 + 2]-cycloaddition of various ,-cyclic azomethine imines to 3-nitrobenzofurans. This process is a rare example of their dearomatization. We have also extended this process to the related 3-nitro-4-chromenes as dipolarophiles.

One-Step Synthesis of Triphenylphosphonium Salts from (Het)arylmethyl Alcohols.

Two approaches for the synthesis of substituted phosphonium salts from easily available benzyl alcohols and their heterocyclic analogs have been developed. The developed protocols are complementary: the direct mixing of alcohol, trimethylsilyl bromide, and triphenylphosphine in 1,4-dioxane followed by heating at 80 °C was found to be more efficient for acid-sensitive substrates, such as salicyl or furfuryl alcohols as well as secondary benzyl alcohols, while a procedure including sequential addition of trimethylsilyl bromide and triphenylphosphine gave higher yields for benzyl alcohols bearing electroneutral or electron-withdrawing substituents.

Design, synthesis and biological evaluation of 2-quinolyl-1,3-tropolone derivatives as new anti-cancer agents.

Tropolones are promising organic compounds that can have important biologic effects. We developed a series of new 2-quinolyl-1,3-tropolones derivatives that were prepared by the acid-catalyzed reaction of 4,7-dichloro-2-methylquinolines with 1,2-benzoquinones. 2-Quinolyl-1,3-tropolones have been synthesized and tested for their anti-proliferative activity against several human cancer cell lines.

-functionalization of calix[4]arene with 1,3,7-triazapyrene in the design of novel fluorophores with the dual target detection of Al and Fe cations.

A -functionalization strategy has successfully been applied to the synthesis of novel 1,3,7-triazapyrene derivatives of calixarenes. The key synthetic step in these transformations providing the direct C-C bond formation is nucleophilic substitution of hydrogen (S ) in 1,3,7-triazapyrene. General photophysical characteristics for these macrocyclic compounds, as well as features in emission properties upon addition of various metal cations have been elaborated.

Eco-friendly synthesis of fused pyrano[2,3-]pyrans ammonium acetate-mediated formal oxa-[3 + 3]cycloaddition of 4-chromene-3-carbaldehydes and cyclic 1,3-dicarbonyl compounds.

Various substituted polycyclic pyrano[2,3-]pyrans were synthesized the condensation of 4-chromene-3-carbaldehydes and their areno-condensed analogues with hetero- and carbocyclic 1,3-dicarbonyl compounds in acetic acid. Ammonium acetate was used as a green catalyst for the reaction. The process also involves the subsequent Knoevenagel condensation and 6π-electrocyclization of the 1-oxatriene intermediates formed.

Diazapyrenes: interaction with nucleic acids and biological activity.

The review summarizes data on the practical aspects of the interaction of nucleic acids with diazapyrene derivatives. The information on biological activity is given and the probable mechanisms underlying the action of diazapyrenes are analyzed. It contains 119 references.