Modification of the Zeolite Heulandite with N-(3-Triethoxysilylpropyl)guanidines Offers an Effective Approach to Enhancing Its Adsorption Capacity for Heavy Metal Ions.

Zeolites are widely used as adsorbents due to their porous structure and ion-exchange capabilities. However, their adsorption efficiency for heavy metal ions remains limited. To enhance their performance, the natural zeolite heulandite () was functionalized with guanidine derivatives: N-[3-(triethoxysilyl)propyl]guanidine (), -aminoguanidine (), and -acetyl-guanidine ().

Regioselectivity Switching in the Tandem Reaction of Skipped Diynones with Allylic Alcohols: Stereoselective Synthesis of 4-Allyl-2-Methylene-3(2)-Furanones.

A novel base-catalyzed synthesis of hitherto unknown 4-allyl-2-methylene-3(2)-furanones from skipped diynones and allylic alcohols via nucleophilic addition/Claisen rearrangement/cyclization reaction is described. An important role of the employed catalytic system for the regioselective switching in the cyclization step from 3-allyl-4-pyrones to isomeric 4-allyl-3(2)-furanones is discussed. The isolation of main intermediates of the tandem reaction and study of their reactivity allowed us to develop a convenient two-stage protocol for stereoselective 4-allyl-2-methylene-3(2)-furanone formation featuring a good substrate tolerance and good yields of target products.

Controlled Switching from Spirobi[pyrrolo[1,2-]thiazoles] to Pyrrolo[1,2-]thiazole-3-thiones during the Cyclization of 2-Acylethynylpyrroles with Carbon Disulfide.

Base-catalyzed cycloaddition of 2-acylethynylpyrroles with carbon disulfide (NaOH, DMSO, room temperature) proceeds stereoselectively to provide spirobi[pyrrolo[1,2-]thiazoles] and pyrrolo[1,2-]thiazole-3-thiones, both integrated with -α,β-ethylenic ketones in 40-81 and 35-86% yields, respectively. The switching between spirobi[pyrrolo[1,2-]thiazoles] and pyrrolo[1,2-]thiazole-3-thiones is controlled by the reactant ratio or the substituents in the pyrrole ring. Thus, unique pyrrolothiazole/-α,β-ethylenic ketone hybrids as prospective for medicinal chemistry, materials science, and organic synthesis are becoming readily accessible.

Double Selectivity of Cycloaddition Opens a Way to 1,2-Oxazoline-Pyrrole Ensembles via Nitrile Oxide Cycloaddition to -Allenylpyrrole-2-Carbaldehydes.

Cycloaddition of 1,3-dipoles to allenes usually proceeds in a nonselective way. Herein, we report on an efficient metal-free cycloaddition of nitrile oxides to readily available -allenylpyrrole-2-carbaldehydes with formation of 1,2-oxazoline-pyrrole ensembles. The reaction features a high regioselectivity and occurs only at the -bond of the allene with a very specific direction of the 1,3-dipole attack.

Base-Mediated Synthesis of Polysubstituted Pyrroles from -Allyl Ketimines and Alkynes: Interplay of Carbanions.

Terminal (het)arylacetylenes react (KOBu/DMSO, 60 °C, 1 h) with -allyl ketimines to afford 2-(het)aryl-4-(het)arylmetyl-5-ethylpyrroles in up to 71% yield as a result of the interaction of acetylenic and azadienic carbanions with C=N and C≡C bonds. This new reaction opens a one-pot access to synthetically and pharmaceutically prospective compounds.

Beyond classic acetylene chemistry: base-mediated self-organization of acetylenes with nitriles toward rarely functionalized dihydropyridinimines.

Herein, we disclose that two molecules of (het)arylacetylenes and two molecules of aliphatic nitriles readily undergo organization in the KOBu/DMSO system at 40 °C, forming dihydropyridines bearing imine, acetylenic, (het)aromatic and aliphatic substituents in up to 77% yield. This unprecedented reaction highlights the generality of the recently discovered self-organization of complex molecules where several acetylene units combine with simple nucleophiles, a phenomenon steered by acetylenic carbanions.

Organic Base-Catalyzed Cascade Reaction of CF-Iminopropargylic Alcohols with Carboxylic Acids: an Approach to β-CF β-Aminoenones.

A novel approach to the synthesis of β-CF β-aminoenones by the organic amine base-catalyzed reaction of CF-iminopropargylic alcohols with carboxylic acids is reported. The advantages of the protocol are the ease of operation, available starting materials, and simple tertiary amine catalysts.

Macrocyclic Bridgehead Fluorophores, Pyrrolyl-diazabicyclo[8.3.1]tetradecadienones, with Giant Stokes Shifts.

A previously unknown class of fluorophores was discovered, which represents 14-membered bridgehead heterocycles, pyrrolyl-diazabicyclo[8.3.1]tetradecadienones, herein referred to as PY-14-ONEs.

Photoreactions of Semi-Stiff-Diarylethenes Based on the Cyclohexenol Motif.

Nonsymmetric diarylethenes with an additional "stiff" cyclohexenol ring undergo various types of tandem transformations launched by light-induced 6π-photocyclization. Among these, there are two novel reactions (formal [1,3]-H migration and complete aromatization to an anthracene derivative) as well as photorearrangement and formal methane elimination. This diverse reactivity demonstrates the great potential of --diarylethenes in synthetic photochemistry.

Functionalized 2,3'-Bipyrroles and Pyrrolo[1,2-]imidazoles from Acylethynylpyrroles and Tosylmethylisocyanide.

An efficient method for the synthesis of pharmaceutically prospective but still rare functionalized 2,3'-bipyrroles (in up to 80% yield) by the cycloaddition of easily available acylethynylpyrroles with tosylmethylisocyanide (TosMIC) has been developed. The reaction proceeds under reflux (1 h) in the KOH/THF system. In the -BuONa/THF system, TosMIC acts in two directions: along with 2,3'-bipyrroles, the unexpected formation of pyrrolo[1,2-]imidazoles is also observed (products ratio~1:1).

Activation of Anthraquinone's Electrophilicity by Light for a Dynamic C-O Bond.

Coupling of photoswitching with dynamic covalent chemistry enables control of the formation and cleavage of covalent bonds by light irradiation. -Aryloxyanthraquinones feature an exclusive ability to switch electrophilicity by interconversion between - and -quinone isomers, which was used for the first time for the implementation of a dynamic C-O bond. Photogenerated -isomers undergo a concerted -Michael addition of phenols to give hitherto unknown 4-hydroxy-10,10-diaryloxyanthracen-9-ones.

Synthesis of Tetrazines from -Allenylpyrrole-2-carbaldehydes and pH-Controlled Reversible Fragmentation.

A one-pot highly selective approach to the synthesis of hitherto unknown tetrahydropyrrolo[2',1':3,4]pyrazino[1,2-]pyrrolo[2',1':3,4]pyrazino[1,2-][1,2,4,5]tetrazine ensembles from simple and available -allenylpyrrole-2-carbaldehydes and hydrazines has been developed. The reaction proceeds in a very facile manner and tolerates different substituents in both pyrroles and hydrazines. The novel class of organic compounds, tetrahydrodipyrrolodipyrazinotetrazines, proves to be promising pH-sensitive switchers to deliver -aminopyrrolopyrazinium salts in acidic media and then again tetrahydrodipyrrolodipyrazinotetrazines in basic media.

New Functional Alkoxysilanes and Silatranes: Synthesis, Structure, Properties, and Possible Applications.

The aza-Michael reaction of 3-aminopropyltriethoxysilane () and -silatrane () with acrylates affords functionalized silyl-(-) and silatranyl-(-) mono- and diadducts with up to a 99% yield. Their structure has been proved with IR and NMR spectroscopies, mass spectrometry and XRD analysis. The hydrolytic homo-condensation of triethoxysilanes - gives siloxanes -, which form complexes with Ag, Cu, and Ni salts.

2,3-Diarylmaleate salts as a versatile class of diarylethenes with a full spectrum of photoactivity in water.

There is incessant interest in the transfer of common chemical processes from organic solvents to water, which is vital for the development of bioinspired and green chemical technologies. Diarylethenes feature a rich photochemistry, including both irreversible and reversible reactions that are in demand in organic synthesis, materials chemistry, and photopharmacology. Herein, we introduce the first versatile class of diarylethenes, namely, potassium 2,3-diarylmaleates (DAMs), that show excellent solubility in water.

Rapid, room-temperature self-organization of polyarylated 1-pyrroles from acetylenes and nitriles in the KOBu/DMSO system.

We have discovered that three molecules of arylacetylene are rapidly (15 min) assembled with one molecule of nitrile at room temperature in the KOBu/DMSO system to afford 2-aryl-3-arylethynyl-4-aryl-5-benzyl-1-pyrroles in up to 76% yield. We assume that this unprecedented self-organization process involves the cascade addition of acetylenic carbanions, first to the CN, then to the CC and CC bonds of the intermediates, followed by pyrrole ring closure the intramolecular nucleophilic addition of the NH functional group to the CC bond of the final intermediates.

New 3-Aminopropylsilatrane Derivatives: Synthesis, Structure, Properties, and Biological Activity.

The biologically active compound 3-aminopropylsilatrane (a compound with a pentacoordinated silicon atom) underwent an aza-Michael reaction with various acrylates and other Michael acceptors. Depending on the molar ratio, the reaction yielded Michael mono- or diadducts (11 examples) containing functional groups (silatranyl, carbonyl, nitrile, amino, etc.).

Novel Route to Cationic Palladium(II)-Cyclopentadienyl Complexes Containing Phosphine Ligands and Their Catalytic Activities.

The Pd(II) complexes [Pd(Cp)(L)][BF] were synthesized via the reaction of cationic acetylacetonate complexes with cyclopentadiene in the presence of BF∙OEt ( = 2, = 1: L = PPh (), P(-Tol), (-methoxyphenyl)phosphine (TOMPP), -2-furylphosphine, -2-thienylphosphine; = 1, = 1: L = dppf, dppp (), dppb (), 1,5-bis(diphenylphosphino)pentane; = 1, = 2 or 3: 1,6-bis(diphenylphosphino)hexane). Complexes - were characterized using X-ray diffractometry. The inspection of the crystal structures of the complexes enabled the recognition of (Cp)⋯(Ph-group) and (Cp)⋯(CH-group) interactions, which are of C-H…π nature.

Quantum-Chemical Study of the Assembly Mechanism of 1-Pyrrolines from -Benzylaldimines and Arylacetylenes in KOBu/DMSO Superbasic Medium.

By using a quantum-chemical approach, B2PLYP-D2/6-311+G**//B3LYP/6-31+G*, we have carried out a detailed study of the assembly of 1-pyrrolines from -benzyl-1-phenylmethanimine and phenylacetylene in the superbasic medium KOBu/dimethyl sulfoxide (DMSO). In this way, we have considered, both theoretically and experimentally, the mechanisms of the assembly through a concerted and stepwise nucleophilic cycloaddition and have addressed the side processes accompanying the assembly. It is found that the assembly via the concerted cycloaddition is kinetically more favorable than that via the stepwise cycloaddition.

Reactions of α-Functionally Substituted Enals with Terminal Alkynes: Unexpected Assembly of 2-Amino-2-Cyclopentenones.

The reactions of α-chalcogen, α-halo, or α-amino functionally substituted enals with terminal alkynes leading either to corresponding propargyl alcohols (for O-, S-, Cl-, and Br-bearing substrates) or unexpected 2-amino-2-cyclopentenones (for aminoenals) are described. The key feature of these reactions is the rearrangement of adducts bearing amino groups on silica gel that triggered further cyclization to five-membered carbocycles.

Concise assembly of 7-ethynyl-6,8-dioxabicyclo[3.2.1]octanes from acetylenes and ketones.

2-Acetyl-3,4-dihydropyrans, assembled from acetylene gas and ketones in a one-pot procedure, are ethynylated with acetylenes (KOBu/DMSO, 15 °C, 2 h) to give acetylenic alcohols, which readily cyclize (TFA, rt, 5 min) to 7-ethynyl-6,8-dioxabicyclo[3.2.1]octanes in up to 92% yield.

Contributing to Biochemistry and Optoelectronics: Pyrrolo[1',2':2,3]imidazo[1,5-]indoles and Cyclohepta[4,5]pyrrolo[1,2-]pyrrolo[1,2-]imidazoles via [3+2] Annulation of Acylethynylcycloalka[]pyrroles with Δ-Pyrrolines.

Available pyrrolylalkynones with tetrahydroindolyl, cycloalkanopyrrolyl, and dihydrobenzo[]indolyl moieties, acylethynylcycloalka[]pyrroles, are readily annulated with Δ-pyrrolines (MeCN/THF, 70 °C, 8 h) to afford a series of novel pyrrolo[1',2':2,3]imidazo[1,5-]indoles and cyclohepta[4,5]pyrrolo[1,2-]pyrrolo[1,2-]imidazoles functionalized with an acylethenyl group in up to an 81% yield. This original synthetic approach contributes to the arsenal of chemical methods promoting drug discovery. Photophysical studies show that some of the synthesized compounds, e.

Unexpected Decarbonylation of Acylethynylpyrroles under the Action of Cyanomethyl Carbanion: A Robust Access to Ethynylpyrroles.

It has been found that the addition of CHCN anion to the carbonyl group of acylethynylpyrroles, generated from acetonitrile and -BuOK, results in the formation of acetylenic alcohols, which undergo unexpectedly easy (room temperature) decomposition to ethynylpyrroles and cyanomethylphenylketones (-Favorsky reaction). This finding allows a robust synthesis of ethynylpyrroles in up to 95% yields to be developed. Since acylethynylpyrroles became available, the strategy thus found makes ethynylpyrroles more accessible than earlier.

Diastereoselective synthesis of tetrahydropyrrolo[1,2-]oxadiazoles from functionalized Δ-pyrrolines and generated nitrile oxides.

Tetrahydropyrrolo[1,2-]oxadiazoles have been synthesized in good-to-excellent yields the cycloaddition of nitrile oxides ( generated from aldoximes) to readily accessible functionalized Δ-pyrrolines. The reaction proceeds smoothly at room temperature in a two-phase system in the presence of sodium hypochloride as an oxidant to diastereoselectively afford pharmaceutically prospective 1,2,4-oxadiazolines fused with a five-membered ring. The reaction tolerates a broad range of substrates, including those with oxidant-sensitive functional groups and competitive reaction sites.

Substituent-Dependent Divergent Synthesis of 2-(3-Amino-2,4-dicyanophenyl)pyrroles, Pyrrolyldienols and 3-Amino-1-acylethylidene-2-cyanopyrrolizines via Reaction of Acylethynylpyrroles with Malononitrile.

An efficient method for the synthesis of pharmaceutically and high-tech prospective 2-(3-amino-2,4-dicyanophenyl)pyrroles (in up to 88% yield) via the reaction of easily available substituted acylethynylpyrroles with malononitrile has been developed. The reaction proceeds in the KOH/MeCN system at 0 °C for 2 h. In the case of 2-acylethynylpyrroles without substituents in the pyrrole ring, the reaction changes direction: instead of the target 2-(3-amino-2,4-dicyanophenyl)pyrroles, the unexpected formation of pyrrolyldienols and products of their intramolecular cyclization, 3-amino-1-acylethylidene-2-cyanopyrrolizines, is observed.