Zinc(II) metal-organic frameworks with 1,4-diazabicyclo[2.2.2]octane N,N′-dioxide: control of the parameters of the cationic porous framework and optical properties

Russian Chemical Bulletin - Four zinc metal-organic frameworks (MOFs) with 1,4-diazabicyclo[2.2.2]octane N,N′-dioxide (odabco) as a bridging ligand were synthesized by varying the solvent and...     

Infrared study of hydrogen bonds involving 2,2′-bipyridine and 2,2′-bipyrimidine. Influence of equivalent nitrogen atoms on the hydrogen bond strength

Hydrogen bonding between proton donors (phenols and water) and 2,2′-bipyridine (BPR) or 2,2′-bipyrimidine (BPM) has been investigated by infrared and FT-infrared techniques. The thermodynamic parameters (K, - ΔH, - ΔS°) and the frequency shifts of the ν_OH stretching vibrations have been determined in carbon tetrachloride solution. The spectroscopic results suggest that the complexes formed between phenols covering a large pK_a range (10.3–3.50) and BPR or BPM are of the normal OH⋯N type. The thermodynamic and spectroscopic properties of the BPR and BPM complexes are compared with those previously reported for the interaction between the same proton donors and the model molecules pyridine and pyrimidine. The BPR and pyridine complexes belong to the same series. The behaviours of BPM and pyrimidine are in complete contrast, the thermodynamic parameters and the related proton affinity being much higher for BPM than for pyrimidine. The results are probably ascribable to the presence of two equivalent neighbouring nitrogen atoms, the approach of a hydroxylic proton donor being greatly favoured in this electron-rich region. This effect does not exist in BPR, owing to its transoid configuration in solvents of weak polarity.     

The effect of styrene α-substituents on the regiochemistry of [2+2] cycloadditions with difluoroallene.

Consistent with our hypothesis for a mechanism involving two kinetically-distinct diradical intermediates, the observed effects of styrene α-substituents can be explained as deriving either from steric effects or radical stabilizing effects.     

Synthesis and structure of manganese(ii) coordination polymers with 1,4-diazabicyclo[2.2.2]octane N,N′-dioxide: solvent and template effects

Russian Chemical Bulletin - New metal-organic frameworks [Mn(DMF)2(odabco)2](ClO4)2 · H2O (1), [Mn(H2O)2? (HCOO)2] · odabco (2), and [Mn(Hodabco)2(odabco)3](NO3)4 (3) were...     

Synthesis and Investigation of Mass Spectra of 3-[5′-(2′-Substituent)thienyl]benzo[5,6]coumarins

3-[5'-(2'-Hydroxycarbonyl)thienyl]benzo[5,6]coumarin ( 3 ) was prepared via condensation of 2 with thioglycolic acid in the presence of AcONa and Ac 2 O. Esterification of 3 with alcohols gave 3-[5'-(2'-alkoxycarbonyl)thienyl]benzo[5,6]-coumarins ( 4a , b ). The chemical behavior of 4 toward nucleophilic reagents (such as ammonia, hydroxyl amine, and hydrazine derivatives) is described. The electron impact ionization mass spectra of compounds 4b , 5 , and 8a , b show a weak molecular ion peak and a base peak of m / z 278 resulting from a cleavage fragmentation. In contrest compounds 3 and 4a show a base peak of m / z 250 and m / z 74 resulting from fragmentation. Compounds 9 and 10 give a characteristic fragmentation pattern with a very stable fragment of m / z 305.     

Studies on the Cyclisation of 4-[2′-Cyclohexenyl]-3-hydroxy[1]benzopyran-2-one

The bicyclic coumarin derivative-1, 3 propano-2-bromo-1,2-dihydro-3H-pyrano [2, 3-c] [1]benzo-pyran-5-one (8) was synthesised by a sequence of reaction viz. acetylation of 4-[2′-cyclohexenyl] -3-hydroxy [1] benzopyran-2-one (4), addition of bromine to cyclohexenyl double bond and treating the resulting acetyldi-bromo derivative (7) with 4% alcoholic KOH. Benzofuro [2, 3-c] [1] -benzopyran-6-one (10) was synthesised from 4 via oxymercuration with mercuric acetate in methanol followed by dehydrogenative damercuration with Pd-C in refluxing diphenyl ether.     

The application of copolymer-coated graphene oxide-Fe3O4 in the highly efficient synthesis of 2′-aminospiro[indeno[1,2-b]quinoxaline-11,4′-[4'H] pyran]-3′-carbonitrile and 2′-aminospiro[indeno-2,4′-[4'H]pyran]-3′-carbonitrile

A magnetic nanocomposite based on graphene oxide was prepared. Fe₃O₄ nanoparticles were loaded on graphene oxide sheets and GO-Fe₃O₄ was covered by aniline-pyrrole copolymer to afford poly(Py-co-Ani)@GO-Fe₃O₄. This nanocomposite was characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, vibrating sample magnetometry, X-ray diffraction, thermogravimetric analysis, and X-ray photoelectron spectroscopy techniques, and its catalytic activity was evaluated in the multicomponent synthesis of 2′-aminospiro[indeno[1,2-b]quinoxaline-11,4′-[4'H]pyran]-3′-carbonitrile and 2′-aminospiro[indeno-2,4′-[4'H]pyran]-3′-carbonitrile derivatives. This magnetically separable catalyst is heterogeneous noncorrosive, highly efficient, and reusable.     

Cyclopenta[b]thienyl ligand in organometallic chemistry. Studies of the regioselectivity of the synthesis of new σ-element-substituted cyclopenta[b]thiophene derivatives

Reactions of 2-ethyl-5-methylcyclopenta[b]thienyllithium (thiopentalenyllithium) (2) with various electrophilic reagents afford σ-element-substituted thiopentalenes. However, the reaction with Ph₃SnCl yields only one of two possible isomers,viz, triphenyl(4H-cyclopenta[b] thiophen-4-yl)stannane (4c), whereas the reactions with Me₃SiCl, Me₃SiCl, or Ph₂PCl give both possible isomers,viz., trimethyl(6H-cyclopenta[b]thiophen-6-yl)silane (3a) and trimethyl(4H-cyclopental[b]thiophen-4-yl)silane (4a), trimethyl(6H-cyclopenta[b]thiophen-6-yl)stannane (3b) and trimethyl(4H-cyclopental[b]thiophen-4-yl)stannane (4b), or diphenyl(6H-cyclopenta[b]thiophen-6-yl)phosphine (3d) and diphenyl(4H-cyclopenta[b]thiophen-4-yl)phosphine (4d) in ratios of 1∶2, 1∶2, or 1∶1, respectively. The structure of compound4c was established by X-ray diffraction analysis. The observed regioselectivity of formation of compound4c is attributed to the specific precoordination of the tin atom by the sulfur atom of the thiopentalenyl ligand and to the steric overcrowding of the Sn atom in organotin electrophiles. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1285–1289, July, 2000.     

A DFT study on regioselectivity in the [2 + 2] photocycloaddition of 6-amino-2-(3′-thienoyl)-1,4-benzoquinone and ethylene

DFT-B3LYP studies have been used to understand the realm of [2 + 2] photocycloaddition reactions that lead to the formation of four-membered cyclobutane derivatives. Regioselectivity in these reactions has been explored for the typical system 6-amino-2-(3′-thienoyl)-1,4-benzoquinone and ethylene. The results favor initial attack of ethylene on quinonoid carbon C5 rather than any other position.     

Formation of 3,4-diazabicyclo[4,3,0]non-2-ene and N,N′-azo-3-azabicyclo[3,3,0]octane by oxidation of an alicyclic hydrazine. influence ofpH on the diazene rearrangement

Summary 3,4-Diazabicyclo[4,3,0]non-2-ene and N,N-azo-3-azabicyclo[3,3,0]octane are the main products of the oxidation of N-amino-3-azabicyclo[3,3,0]octane by chloramine. The reaction leads to the transient formation of a saturated bicyclic aminonitrene (diazene). AtpH > 13, the diazene undergoes an intramolecular rearrangement to afford a hydrazone. AtpH < 9, a white solid is formed resulting from the dimerization of the molecular and protonated forms of the aminonitrene. At intermediatepH-values, a mixture of both species is obtained. They have been isolated and characterized by UV, GC/MS, IR, and¹H/¹³CNMR. A reaction mechanism is proposed.

---

Bildung von 3,4-Diazabicyclo[4,3,0]non-2-en und N,N-Azo-3-azabicyclo[3,3,0]oktan durch Oxidation eines alizyklischen Hydrazins. Einfluß despH-Wertes auf die Umlagerung von Diazenen

Zusammenfassung 3,4-Diazabicyclo[4,3,0]-non-2-en und N,N-Azo-3-azabicyclo[3,3,0]oktan sind die Hauptreaktionsprodukte der Oxidation von N-Amino-3-azabicyclo[3,3,0]oktan durch Chloramin. Die Interaktion führt übergangsweise zur Bildung eines gesättigten bizyklischen Aminonitrens (Diazens). Oberhalb despH-Wertes 13 lagert sich das Diazen intramolekular um und bildet ein Hydrazon. Unterhalb despH-Wertes 9 fällt ein weißer Niederschlag aus (Tetrazen), der von einer Dimerisierung zwischen for molekularen und protonierten Form von Aminonitren herrühren dürfte. Für die dazwischenliegenden Werte (9 <pH < 13) erhält man eine Mischung aus beiden Verbindungen. Sie wurden isoliert und mit Hilfe von UV, GC/MS, IR, und¹H/¹³C-NMR untersucht. Ein Reaktionsmechanismus wird vorgeschlagen.

     

Cyclopenta[b]thienyl Ligand in Organometallic Chemistry. Synthesis of Cyclopenta[b]thiophene η5-Complexes with Metal Coordination at the Thiophene Ring

Unlike isoelectronic ⁶-indenyl ruthenium, manganese, and chromium complexes, heating of Mn(CO)₅OTf, [Ru(Cp^*)Cl₄], and Cr(C₁₀H₈)(CO)₃ with isomeric 2-ethyl-5-methylcyclopenta[b]thiophenes leads to the corresponding ⁵-complexes where the metal is coordinated at the C₅-carbocycle. The structure of the complex Mn(Th)(CO)₃ (Th = 2-ethyl-5-methylcyclopenta[b]thienyl) was proved by X-ray analysis.     

Reaction of Pyrrolo[2,1-a][1,4]oxazine-1,6,7-triones with Carbocyclic Enamino Ketones. Synthesis of Spiro[indole-3,2′-pyrroles]

Russian Journal of Organic Chemistry - 8-Aroyl-3,4-dihydro-1H-pyrrolo[2,1-a][1,4]oxazine-1,6,7-triones reacted with 3-benzylamino-5,5-dimethylcyclohex-2-en-1-one to give...     

Synthesis of benzo- and naphtho-fused bicyclo[n.3.1]alkane frameworks with a bridgehead nitrogen function by palladium-catalyzed intramolecular α'-arylation of α-nitroketones

The C-alkylation of cyclic α-nitroketones with α-halobenzyl halides in the presence of DBU followed by a Pd-catalyzed intramolecular C-arylation afforded benzo-and naphtho-fused bicyclo[n.3.1]alkane derivatives (n = 3, 4, 5) in excellent overall yields for the two-step sequence. In some of the reactions starting from α-nitrocyclooctanone, the major products were fused indane derivatives arising from an intramolecular attack of an intermediate Pd species onto the carbonyl group, followed by elimination.     

Influence of Chiral 4-[(S)-2-Methyl-3-hydroxypropyloxy]-4′-cyanobiphenyl on the Properties of Liquid Crystalline Mixture on the Base of 4-Alkyloxy-4′-cyanobiphenyles

Russian Journal of General Chemistry - The formation of a chiral nematic mesophase by doping a liquid crystalline mixture of 4-alkyloxy-4′-cyanobiphenyls with chiral...     

Synthesis of spiro[furan-3,3′-indolin]-2′-ones by PET-catalyzed [3+2] reactions of spiro[indoline-3,2′-oxiran]-2-ones with electron-rich olefins

An efficient procedure for the synthesis of spiro[furan-3,3′-indolin]-2-ones and dispiro[cycloalkane-1,2′-furan-3′,3″-indolin]-2″-ones has been achieved in high yields and stereoselectivity by photoinduced electron transfer-catalyzed [3+2] reactions of substituted spiro[indoline-3,2′-oxiran]-2-ones with olefins. The reactions proceed by ring opening of spiro[indoline-3,2′-oxiran]-2-ones via C_β–O bond cleavage and subsequent cycloaddition with olefins by using 2,4,6-triphenylpyrylium tetarfluoroborate (TPT) as a sensitizer.     

Synthesis and properties of ruthenium(II) complexes of 3,3′-polymethylene-2-(pyrid-2′-yl)benzo[b]-1,10-phenanthrolines

Coordination abilities of unsymmetrical tridentate ligands, 3,3′-polymethylene-2-(pyrid-2′-yl)-benzo[b]-1,10-phenanthrolines (4) were studied. Reactions of the 3,3′-di- and 3,3′-trimethylene-2-(pyrid-2′-yl)benzo[b]-1,10-phenanthrolines (4b and 4c) with RuCl₃ ? 3H₂O afforded [Ru(4b)₂]²⁺ and [Ru(4c)₂]²⁺ in 57% and 78% yield, respectively, while reactions of the parent non-bridged ligand (4a), tetramethylene-bridged ligand (4d), and fully aromatized ligand (4e) afforded a messy mixture. Reactions of 4 with Ru(tpy)Cl₃ (tpy = 2,2′;6′,2″-terpyridine) afforded [Ru(tpy)(4)]²⁺ in 61–72% yields. UV absorption spectra of the ligands showed four ligand-centered (LC) π–π* transitions and their Ru complexes showed four LC π–π* transitions and one Ru(d_π) → ligand(π*) MLCT. The ligands showed three major emission maxima (λ _emission) in the region of 393–418, 416–445, and 437–471 nm in which λ _emission is highly dependent on the length of the methylene bridge connecting C3 of benzo[b]-1,10-phenanthroline and C3 of pyridine. Ru complexes with fully aromatic ligand, [Ru(tpy)(4e)]²⁺, and the most distorted ligand, [Ru(tpy)(4d)]²⁺, showed two emission maxima at 410 and 444–446 nm, while the others showed one emission at 410 nm. Each of the emission maxima is bathochromatically shifted from the complex with the most distorted ligand (4d) to the complex with fully aromatized planar ligand (4e) indicating lower energy emission.     

Synthesis,crystal structure and Raman spectra of [dabcoH2]CuICl3, [dabcoH2]3Cl4CuIICl4(DMSO) and Cu3Cl3(dabco)(DMSO) (dabco = 1,4-diazabicyclo [2.2.2] octane)

Dissolving elemental copper in a CCl₄–DMSO mixture in the presence of dabco (dabco = 1,4-diazabicyclo [2.2.2] octane) resulted in the formation of a compound with the composition [dabcoH₂][CuCl₃] featuring a univalent copper salt. This compound, composed of discrete dabcoH₂²⁺ cations and CuCl₃^2? anions, represents the first example of a copper(I) chloride derivative containing a doubly protonated [dabcoH₂]²⁺ unit, and a very rare example of the oxidative dissolving of copper in a CCl₄–DMSO mixture to give a Cu(I) compound. The addition of some drops of water to the initial reaction mixture led to the formation of the [dabcoH₂]₃Cl₄CuCl₄(DMSO). Three [dabcoH₂]²⁺ units and four Cl^? anions, bound via N–H…Cl hydrogen bonds, form a horseshoe-like cationic fragment. The divalent copper ion possesses a rather unusual pseudo-tetrahedral surrounding. The comproportionation reaction of CuCl₂·2H₂O and copper powder in the presence of dabco in DMSO results in the formation of the Cu₃Cl₃(dabco)(DMSO) complex. Copper and chlorine ions form unprecedented Cu₆Cl₆ cores, interconnected by neutral dabco linkers into infinite 2-D layers. All the compounds were characterized using the single-crystal X-ray diffraction technique and Raman spectroscopy.