Synthesis of nitrogen-containing heterocycles. 3. Formation and structure of new 1,2,4-triazole derivatives

Treatment of N(3)-[(2-cyano-2-ethoxycarbonyl)vinyl]amino-N(4),N(4)-dimethylaminomethylenehydrazones of aromatic carbonyl compounds with hot acetic acid resulted in the formation of symmetrical gem-bis-(3-dimethylamino-1,2,4-triazol-1-yl)methanes, (3-dimethylamino-1,2,4-triazol-1-yl)arylmethyl acetates, and (3-dimethylamino-1,2,4-triazol-1-yl)alkenes of a gem-diaryl type depending upon whether the carbonyl compound was aldehyde or ketone.     

Synthesis of di(Imdazolium) and di(Pyrazolium) Salts as Precursors for N-heterocyclic Dicarbene Complexes

Alpha,omega-bis(pyrazol-1-yl)alkanes and alpha,omega-bis(imidazol-1-yl)alkanes with spacers consisting of four to ten methylene groups have been prepared from pyrazole, 3,5-dimethylpyrazole or imidazole and corresponding dibromoalkanes in a superbasic medium KOH-DMSO. The proposed method of synthesis allowed the preparation of new flexible bidentate ligands without the need to use toxic solvents and tedious workup procedures. Bis(pyrazol-1-yl)alkanes were further functionalized for their use as precursors for “non-classical” mesoionic N-heterocyclic carbene ligands. One the first step, iodine atoms were introduced to positions 4 of pyrazole rings by oxidative iodination using I₂-HIO₃ system. On the next step, nitrogen atoms in positions 2 of pyrazole rings were alkylated using several agents. Reaction with methyliodide unexpectedly led to the formation of only mono-alkylated products even after 7 days of refluxing in a neat alkyliodide. Methylation by trimethyloxonium tetrafluoroborate or methyltriflate led to dimethylated products in high yields. Bis(imidazol-1-yl)alkanes were easily alkylated by methyliodide to give di(imidazolium) salts – precursors to “classic” N-heterocyclic dicarbenes.     

Novel tris(5-aryl-1H-tetrazol-1-yl)methanes and 2-dichloromethyl-5-aryl-2H-tetrazoles and noncovalent interactions in their crystal structure

A series of tris(5-aryl-1H-tetrazol-1-yl)methanes ( 3a-3g ) and 2-dichloromethyl-5-aryl-2H-tetrazoles ( 4a-4d ) were synthesized by reaction of 5-aryl-NH-tetrazoles with trichloromethane in strong aqueous basic condition. The compounds obtained were fully characterized by means of HRESI-MS, ¹H and ¹³C{¹H} NMR spectroscopies, as well as by single-crystal X-ray diffraction (for 3a , 3b , 4d ). Inspection of the X-ray diffraction data and Hirshfeld surface analysis for tris(5-aryl-1H-tetrazol-1-yl)methanes 3a , b and 2-dichloromethyl-5-aryl-2H-tetrazole 4d showed the presence of noncovalent π-hole•••lone pair and π-hole•••π interactions involving electrophilic tetrazole carbon atom.     

Uncatalyzed addition of indoles and N-methylpyrrole to 3-formylchromones: synthesis and some reactions of (chromon-3-yl)bis(indol-3-yl)methanes and E-2-hydroxy-3-(1-methylpyrrol-2-ylmethylene)chroman-4-ones

(Chromon-3-yl)bis(indol-3-yl)methanes and E-2-hydroxy-3-(1-methylpyrrol-2-ylmethylene)chroman-4-ones have been obtained in good yields from 3-formylchromones on reaction with indoles and N-methylpyrrole under solvent-free conditions. Reactions of (chromon-3-yl)bis(indol-3-yl)methanes with guanidine carbonate and hydrazine hydrate proceed with the participation of the chromone ring system and lead to the formation of the corresponding pyrimidines and pyrazoles bearing the bis(indol-3-yl)methyl moiety.     

Syntheses and transformations of substituted benzazolyl- and tetrazolyl(benzotriazol-1-yl)methanes

Condensation reactions of o-hydroxy- and o-mercaptoanilines, and o-phenylenediamine with (benzotriazol-1-yl)acetic acid result in (1,3-benzazol-2-yl)(benzotriazol-1-yl)methanes. Cycloaddition of sodium azide to (benzotriazol-1-yl)acetonitrile leads to (1,2,3,4-tetrazol-5-yl)(benzotriazol-1-yl)methane. The diazolo-substituted benzotriazolylmethanes thus obtained were mono- and di-alkylated at the methylene group and the displacement of the benzotriazole group by nucleophiles was investigated.     

Efficient solvent-free synthesis of bis(indolyl)methanes on SiO<Subscript>2</Subscript> solid support under microwave irradiation

An efficient synthesis of bis(indolyl)methanes was developed. Bis(indolyl)methanes were synthesized starting from various aromatic aldehydes with indole under microwave irradiation and solvent-free conditions (85–98 %). Solid support SiO₂ was found to possess favorable catalytic and dispersancy parameters for the condensation reaction. Moreover, novel bis(indolyl)methanes containing an isoxazole ring were synthesized via this method in excellent yields (> 94 %) using 3-substituted isoxazole-5-carbaldehydes and indole.     

Acid-catalyzed reactions of 3-(hydroxymethyl)- and 3-(1-hydroxyethyl)pyrazolo[1,5-a]pyridines

Treatment of 3-(hydroxymethyl)pyrazolo[1,5-a]pyridines with trifluoroacetic acid in refluxing dichloro-methane led to the formation of bis(pyrazolo[1,5-a]pyrid-3-yl)methanes or bis[(pyrazolo[1,5-a]pyrid-3-yl)]-methyl ethers depending upon the concentration of trifluoroacetic acid. In contrast, similar treatment of 3-(1-hydroxyethyl)pyrazolo[1,5-a]pyridines gave a mixture of 3-vinylpyrazolo[1,5-a]pyridines and 1,3-bis(pyrazolo-[1,5-a]pyrid-3-yl)-1-butenes.     

Uncatalyzed addition of indoles and N-methylpyrrole to 3-formylchromones: synthesis of (chromon-3-yl)bis(indol-3-yl)methanes and E-2-hydroxy-3-(1-methylpyrrol-2-ylmethylene)chroman-4-ones under solvent-free conditions

(Chromon-3-yl)bis(indol-3-yl)methanes and E-2-hydroxy-3-(1-methylpyrrol-2-ylmethylene)chroman-4-ones have been obtained in good yields from 3-formylchromones on reaction with indoles and N-methylpyrrole under solvent-free conditions.     

Substituent effect of fluorine atom on benzothiadiazole bridging unit in dye sensitized solar cells

Dye sensitized solar cells performances using two organic dyes with fluorinated-benzothiadiazole spacer, 3-{5-[7-(5-{4-[Bis(9,9-dimethyl-9H-fluoren-2-yl)-amino]-5-fluoro-phenyl}thiophen-2-yl)benzo-[1,2,5]thiadiazol-4-yl]thiophen-2-yl}-2-cyano acrylic acid (JK-311) and 3-{5-[7-(5-{4-[Bis(9,9-dimethyl-9H-fluoren-2-yl)-amino]-5,6-difluorophe-nyl}thiophen-2-yl)benzo-[1,2,5]thiadiazol-4-yl]thiophen-2-yl}-2-cyano acrylic acid (JK-312), were systematically investigated by solar simulation equipment, stepped light-induced transient measurements of photocurrent and voltage, and electrochemical impedance spectroscopy. To investigate substituent effect of fluorine atom on benzothiadiazole, molecular orbital calculations of two dyes using a time dependent density functional theory model with B3LYP/3-31G* were also carried out. JK-312 showed a unique electronic transition from HOMO-1 to LUMO. Short circuit current and open-circuit voltage in DSSCs performances were increased by the introduction of fluorine atom into spacer segment, compared to fluorine-free dyes.     

Lithium-silylindolide als Precursor für 1,2-, 1,3-Bis(silyl)indole und Bis(indol-1,3-yl)silane

Lithium-silylindolide as Precursor of 1,2-, 1,3-Bis(silyl)indoles and Bis(indole-1,3-yl)silane Lithium-indolide reacts with difluorosilanes (F₂SiR₂: R = CHMe₂ ( 1 ); CMe₃ ( 2 )) in a molar ratio 2 : 1 with formation of bis(indole-1-yl)silanes. The 1-(di-tert-butylfluorosilyl)-3-(fluorodiisopropylsilyl)indole ( 3 ) is obtained in the reaction 1-(di-tert-butylfluorosilyl)-3-lithium-indolide and F₂Si(CHMe₂)₂. In a molar ratio 2 : 1 the bis(1-di-tert-butylfluorosilyl-indole-3-yl)diisopropylsilane 4 is formed. As a byproduct bis(1-di-tert-butylfluorosilyl-indole-3-yl)dimethylmethane ( 5 ) is isolated. A cleavage of THF and the formation of (indole-1-yl)diisopropylvinyloxysilan ( 6 ) occurs in the reaction of 1-diisopropylfluorosilylindole with t-BuLi in THF. 1-(di-tert-butylfluorosilyl)indole reacts with n-BuLi/TMEDA accompanied by an 1,2-anionic silyl group migration to give the 2-(di-tert-butylfluorosilyl)-1-lithiumindolide 7 . Hydrolysis of 7 gives the 2-(di-tert-butylfluorosilyl)indole ( 8 ). In the reaction of 7 with F₂Si(CHMe₂)₂ the 1-(diisopropylfluorosilyl)-2-(di-tert-butylfluorosilyl)indole 9 is obtained. 1-n-Butyl-diisopropylsilylindole ( 10 ) is the product of the reaction of F₂Si(CHMe₂)₂, n-BuLi/TMEDA and indole at –70 °C. Lithium-indolide reacts with 3 to give the 1-(di-tert-butylfluorosilyl)indole-3-yl)(indole-1-yl)-diisopropylsilane ( 11 ), the first example of this class of substances. In the reaction of 1 , F₂SiMe₂, and t-BuLi in THF the 1-(diisopropyl(indole-1-yl)silyl)-3-dimethyl-(3.3-dimethylbutylsilyl)indole 12 is isolated. The crystal structures of 2 , 5 and 9 are discussed.     

Asymmetric diels alder reaction using pyrazole derivatives as a chiral catalyst

N‐Acylpyrazoles ( 1 ) were promising as good dienophiles, which were easily converted into the desired carboxylic derivatives. Bis(pyrazolyl)methanes, which were derived from chiral pyrazoles, showed the activity of chiral catalyst. Particularly 10 mol% of bis(isomenthopyrazol‐1,1′‐yl)methane ( 8a ) catalyzed enantioselectively the Diels Alder reaction up to 40 % ee by the formation of complex with Mg(ClO₄)_2.     

Zur Reaktion von Bis(hydroxyphenyl)methanen mit Phosphorpentachlorid — Phosphocine mit Phosphonium‐ und Phosphoranstruktur [1]

The Reaction of Bis(hydroxyphenyl)methanes with Phosphorus Pentachloride — Phosphocins with Phosphonium and Phosphorane Structure [1] Bis(2‐hydroxyphenyl)methane derivatives react with phosphorus pentachloride to give cyclic dioxaphosphocinium salts, as well as trichloro‐dioxaphosphocins. Chlorination of 6‐chloro‐dioxaphosphocins also leads to trichloro‐dioxaphosphocins. Hydrolysis of the dioxaphosphocin derivatives gives stable cyclic phosphates.     

Acid-catalyzed reactions of 3-(α-hydroxybenzyl)pyrazolo[1,5-a]pyridines

Treatment of 3-(or-hydroxybenzyl)pyrazolo[1,5-a]pyridines with trifluoroacetic acid in dichloromethane resulted in the formation of pyrazolo[1,5-a]pyridines, bis[α-(pyrazolo[1,5-a]pyrid-3-yl)benzyl] ethers, and phenylbis(pyrazolo[1,5-a]pyrid-3-yl)methanes, depending upon the presence or absence of the substituents at the 2- and/or 4-positions and the reaction conditions employed.     

On the Reaction Products of 4‐Substituted 3‐Pyridinesulfonamides with Some Benzenesulfonyl Chloride Derivatives

The reactions of 4‐substituted 3‐pyridinesulfonamides 1a , 1b , 1c , 1d , 1e with benzenesulfonyl chlorides 2a , 2b , 2c , 2d , 2e , 2f in acetonitrile were investigated. Depending on the structure of arylsulfonyl chlorides and the reaction conditions the following four types of products were obtained in good yields: 3‐sulfamoyl‐4‐R‐1‐arylpyridinium chlorides 3 , 4 , 5 , 6 , 7 , 8 ; 1,10‐bis(3‐nitrobenzenesulfonylimino)deca‐2,4,6,8‐tetraene‐2,9‐disulfonamides 9 , 10 , 11 , 12 ; 1‐substituted 1,4‐dihydro‐4‐oxo‐3‐pyridinesulfonamides 13 , 14 ; and 4‐methoxy‐3‐[N‐(2,5‐dichlorophenyl)sulfonyl] sulfonamidates 15 and 16 . The mechanisms of these reactions were discussed.     

Hydrothiolysis of carbofunctional α,β-unsaturated sulfides as an approach to the synthesis of 1,7-dithiocarbonyl compounds

Bis(1-N,N-dimethylimmonio-3-phenylprop-2-en-3-yl) sulfide diperchlorate and (1-N,N-dimethyl-immonio-3-phenylprop-2-en-3-yl) (5,5-dimethyl-1-morpholiniocyclohex-2-en-3-yl) sulfide diperchlorate react with hydrogen sulfide giving rise to the corresponding 1,7-thioxoimmonio sulfides. Treating with the hydrogen sulfide (1-N,N-dimethylimmonio-3-phenylprop-2-en-3-yl) (1-oxo-2-phenyl-inden-3-yl) sulfide perchlorate led to preparation of (1-oxo-2-phenylinden-3-yl) (1-thioxo-3-phenylprop-2-en-3-yl) sulfide. The hydrothiolysis of (5,5-dimethyl-1-morpholiniocyclohex-2-en-3-yl) (1-N,N-dimethylimmonio-2-phenylinden-3-yl) sulfide diperchlorate and (5,5-dimethyl-1-morpholiniocyclohex-2-en-3-yl) (1-oxo-2-phenylinden-3-yl) sulfidea perchlorate resulted in products of the sulfide bond cleavage in the initial immonium salts.     

Acid-catalyzed reaction of pyrazolo[1,5-a]pyridines with aldehydes: Formation of bis(pyrazolo[1,5-a]pyrid-3-yl)methane

Reaction of pyrazolo[1,5-a]pyridines with aldehydes in the presence of trifluoroacetic acid gave bis[pyrazolo[1,5-a]pyrid-3-yl)methanes in high yields.     

Molecular polarizability of the organic substances and their complexes: LX. Molecular volume and spatial structure of the series of heterocycles, their structurally nonrigid derivatives, and chromium tricarbonyl π-complexes in solutions

We have analyzed the molar volumes and structures in solutions of a series of azines, azoles, conformationally nonrigid bis(2-substituted benzimidazol-1-yl)methanes, and chromium tricarbonyl complexes of arenes. For most of the compounds, the rules of molar volume additivity with respect to the bonds and groups increments hold. Molecules of bis(2-substituted benzimidazol-1-yl)methanes exist in the form of conrotatory comformers with aryl fragments being out of the plane of bridging NCN bond angle. Strong linear correlations between the molar volume and molar refraction have been revealed within the studied compounds classes. In the case of chromium tricarbonyl complexes of arenes, the coordination bond polarity has increased with growing π-donor ability of the ligand, the molar volume increment of Cr(CO)₃ has increased as well, due to transfer of π-electron density from the ligand. The simplification of dipole moment and Kerr constant determination has been demonstrated.     

Synthesis of nucleoside analogs of 1,4-oxathiane, 1,4-dithiane,and 1,4-dioxane

The two regioisomers 6-chloro-9-(1, 4-oxathian-3-yl)-9H-purine ( 5 ) and 6-chloro-9-(1,4-oxathian-2-yl)-9H-purine ( 6 ) were obtained when 3-acetoxy-1,4-oxathiane ( 3 ) was subjected to the acid-catalyzed fusion procedure; compound 3 was prepared by a Pummerer reaction with 1,4-oxathiane 4-oxide ( 2 ). The nucleoside analog 6 could he converted into the adenine derivative 7 and 9-(1,4-oxathian-2-yl)-9H-purine-6(1H)thione ( 8 ). The following nucleoside analogs have also been synthesized: 6-chloro-9-(1,4-dithian-2-yl)-9H-purine ( 13 ), 9-(1,4-dithian-2-yl)adenine ( 14 ), 9-(1,4-dithian-2-yl)-9H-purine-6(1H)thione ( 15 ), and 6-chloro-9-(1,4-dioxan-2-yl)-9H-purine ( 18 ).     

Heteroleptische Diorganylzink-Verbindungen mit einem Bis(trimethylsilyl)phosphanido-Substituenten

Heteroleptic Diorganylzinc Compounds with a Bis(trimethylsilyl)phosphido Substituent Dialkylzinc ZnR₂ (Me, Et, iso-Pr, nBu, tBu, CH₂SiMe₃) reacts with one equivalent of bis(trimethylsilyl)-phosphine in carbohydrates to the heteroleptic compounds RZnP(SiMe₃)₂; dependent from the steric demand of the alkyl group R the derivatives are dimeric or trimeric in solution as well as in the solid state. Monomeric bis(trimethylsilyl)phosphido-tris(trimethylsilyl)methylzinc yields from the reaction of lithium tris(trimethylsilyl)methanide and lithium bis(trimethylsilyl)phosphide with zinc(II) chloride. Bis(trimethylsilyl)phosphido-methylzinc crystallizes in the orthorhombic space group P2₁2₁2₁ with {a = 1 007.6(1); b = 1 872.3(3); c = 2 231.0(4) pm; Z = 4} as a trimeric molecule with a central cyclic Zn₃P₃ moiety in the twist-boat conformation. Bis(trimethylsilyl)phosphido-n-butylzinc, that crystallizes in the orthorombic space group Pben with {a = 1 261.7(2); b = 2 253.0(4); c = 1 798.9(2) pm; Z = 4}, shows a simular central Zn₃P₃ fragment. The sterically more demanding trimethylsilylmethyl substituent leads to the formation of a dimeric molecule of bis(trimethylsilyl)phosphido-trimethylsilylmethylzinc {monoklin, P2₁/c; a = 907.2(4); b = 2 079.8(8), c = 1 070,2(3) pm; β = 103,48(1)°; Z = 2}. Bis(trimethylsilyl)phosphido-iso-propylzinc shows in solution a temperature-dependent equilibrium of the dimeric and trimeric species; the crystalline state contains a 1:1 mixture of these two oligomers {orthorhombisch; Pbca; a = 1 859.0(3); b = 2 470.9(2); c = 3 450.7(3) pm; Z = 8}. The Zn? P bond lengths vary in a narrow range around 239 pm, the Zn? C distances were found between 196 and 203 pm.     

RuCl₃·3H₂O catalyzed reactions: facile synthesis of bis(indolyl)methanes under mild conditions

RuCl?·3H?O was found to be an effective catalyst for reactions of indoles, 2-methylthiophene, and 2-methylfuran with aldehydes to afford the corresponding bis(indolyl)methanes, bis(thienyl)methanes, and bis(fur-2-yl)methanes in moderate to excellent yields. Experimental results indicated that mono(indolyl)methanol is not the reaction intermediate under these reaction conditions.