Synthesis and polymerizability of 7,8-dicyano-7,8-diphenylquinodimethane

7,8-Dicyano-7,8-diphenylquinodimethane (DCDPQ) was prepared by oxidation of the dianion of α,α′-dicyano-α,α′-diphenylxylene. ¹H-NMR of a solution of the purified compound showed that the cis and trans isomers were present in a 1:1 ratio. Following further spectroscopic and electronic characterization the polymerizability of the title compound was investigated. DCDPQ did not homopolymerize at 65°C in the presence of AIBN. DCDPQ copolymerized with p-methoxystyrene and p-aminostyrene in the presence of AIBN at 65°C. Characterization of the latter two copolymers indicated that they were nearly alternating. The copolymerization between DCDPQ and p-aminostyrene proceeded in the absence of AIBN.     

Acetylenic amides. 2. The generation and reactions of dianions derived from 2-propynamides

The dianion of N-benzyl-2-propynamide can be generated by the treatment of 4 with two equivalents of LDA at ?65° or ethylmagnesium bromide at ?20°. The trilithio species 6 is readily formed using 3 equivalents of LDA. Reaction of 5 with aldehydes or ketones produce hydroxypropynamides 9 in good yields. Silation of 5a with chlorotrimethylsilane produces N-benzyl-3-trimethylsilyl-2-propynamide ( 13 ) in high yield. Reduction of 9 furnishes either fully saturated amides 15 or partially reduced cis-olefins 16 or 18 . Compounds 16 , on heating, rearrange to 4-ketoamides 17 . Carboxylation of 5a with carbon dioxide produces 3-benzyl-2,4-dioxo-5-oxazidinylacetic acid ( 11 ). Warming 11 in dimethyl sulfoxide results in the loss of carbon dioxide and the formation of N-benzylpyruvamide ( 21 ).     

Reactions of a 4-(trifluoromethyl)thiazole dianion

Treatment of 2-trifluoroacetamido-4-(trifluoromethyl)thiazole with two equivalents of n-butyllithium at -78° produced the thiazole dianion 5 in situ, which reacted preferentially at the 5-position with a variety of electrophiles. These electrophiles include: an aldehyde, ketone, chloroformate, acid chloride, phosphorus oxychloride, silicon chloride, and disulfide. Dianion 5 also combined with dibromodifluoromethane at -98° to give the corresponding 5-(bromodifluoromethyl)thiazole 7 , which is an unusual reaction for an aromatic or heteroaromatic system. Compound 7 was converted to a 4,5-bis-(trifluoromethyl)thiazole 8 using tetrabutylammonium fluoride.     

On the mechanism of the reductive cleavage of anti-9-phenyl-cis-bicyclo[6.1.0]nona-2,4,6-triene

Treatment of the title compound (1a) with potassium in liquid ammonia at ca ?33° immediately afforded the benzylcyclooctatetraene dianion (4a) which, upon quenching with iodine-pentane, gave benzylcyclooctatetraene (5) as the only isolable product. In contrast, treatment of1a with potassium amide in liquid ammonia at ?69° initially afforded the 9-phenylmethylenecyclooctatrienyl anion (6a) as a short-lived intermediate which was then converted to the α-aminobenzylcyclooctatetraene dianion (7a). These results, coupled with the observation that cis-bicyclo[6.1.0]nona-2,4-diene (12) in potassium amide-liquid ammonia affords the cis-bicyclo[6.1.0]nonadienyl anion (8b) which then slowly opens to the methylcyclooctatetraene dianion (4b) at ?12°, lead to the conclusion that4a is produced by a reductive cleavage of1avia a radical anion or dianion.     

Linewidth variation in the dinitronitrosomethyl dianion radical in the slow exchange mode

The treatment of nitromethane or dinitromethane in aqueous alkaline solutions (1 to 2·5 M hydroxide) with nitrogen dioxide yields the dianion radical of dinitronitrosomethane [C(NO₂)₂(NO)\documentclass{article}\pagestyle{empty}\begin{document}$ \buildrel\textstyle.\over= $\end{document}] which at 30° has hfsc of a = 10·75 and 0·65 and a_N^NO = 5·80 g. Restricted rotation about the C? NO bond causes magnetic non-equivalence of the two nitro groups which can slowly exchange giving rise to line broadening. The use of ¹⁵N labeled nitrogen dioxide gave the dianion radical which exists in two equally populated conformations, each of which shows the expected line broadening for a ‘slow exchange’ process in which the nitro groups are being interconverted.     

X-ray study of the third polymorphic structure of μ-oxo-bis[(octaethylporphinato)iron(III)]: [(OEPFe)2O)]

Exposure of a dichloromethane solution of [OEPFe^IIICl], where OEP is the dianion of octaethylporphyrin, to dioxygen results in its transformation into the μ-oxo bridged compound [(OEPFe)₂O)]. The structure of [(OEPFe)₂O)] is determined by X-ray diffraction analysis. It contains binuclear centrosymmetric [(OEPFe)₂O]. The Fe atom is five-coordinated to four N atoms of the porphyrin ring and to one bridging O atom. The compound is characterized by an average Fe-N bond length of 2.096 ?. The Fe-O bond distance is 1.7739(12) ?, the Fe-O-Fe bond angle is 180.0° and the two porphyrin rings are parallel. Crystal data: triclinic crystal system, a = 10.915(4) ?, b = 12.951(4) ?, c = 13.403(4) ?, α = 118.06(1)°, β = 100.33(1)°, Γ = 102.43°, space group, V = 1144.5(1) ?³, Z = 1.     

Nitroimidazoles. V . Synthesis of 1-methyl-2-(2-methyl-4-thiazolyl)nitroimidazoles

Reaction of readily available 2-methyl-4-formylthiazole ( 1 ) with glyoxal and ammonia gave 2-(2-methyl-4-thiazolyl)imidazole ( 2 ). Nitration of 2 with a mixture of nitric acid-sulfuric acid at 100° yielded 2-(2-methyl-4-thiazolyl)-4,5-dinitroimidazole ( 3 ) as the sole reaction product, while nitration at 65° afforded 2-(2-methyl-4-thiazolyl)-4-(or 5)-nitroimidazole ( 4 ). N-Methylation of compound 4 in the presence of base gave 1-methyl-2-(2-methyl-4-thiazolyl)4-nitroimidazole ( 6 ), whereas N-methylation with diazomethane afforded 1-methyl-2-(2-methyl-4-thiazolyl)-5-nitroimidazole ( 5 ). N-Methylation of compound 3 yielded 1-methyl-2-(2-methyl-4-thiazolyl)-3,5-dinitroimidazole ( 7 ) in high yield.     

Structural chemistry of organotin carboxylates XV. Diorganostannate esters of dicyclohexylammonium hydrogen oxalate. Synthesis,crystal structure and in vitro antitumour activity of bis(dicyclohexyl-ammonium) bisoxalatodi-n-butylstannate and bis(dicyclohexylammonium) μ-oxalatobis(aquadi-n-butyloxalatostannate)

Dicyclohexylamine, oxalic acid dihydrate and di-n-butyltin oxide were reacted in 2:2:1 or 2:3:2 stoichiometries in ethanol solution to yield, respectively bis(dicyclohexylammonium) bisoxalatodi-n-butylstannate (1) and bis(dicyclohexylammonium) μ-oxalatobis(aquadi-n-butyloxalatostannate) (2); the hydrate was also obtained upon recrystallization of 1 from moist acetonitrile solution. The crystal structures of the two ammonium stannates have been determined at room temperature. In 1, the tin atom in the dianion exists in a skewtrapezoidal bipyramidal geometry with the basal plane being defined by two bidentate oxalate ligands; each ligand forms asymmetric Sn? O bonds [Sn? O 2.348(4), 2.110(4) Å and 2.112(4), 2.363(4) Å]. The apical sites are occupied by the two organo groups disposed over the weaker Sn? O bonds. In 2, the two tin centres of the dianion are connected via a tetradentate oxalate ligand situated about a centre of inversion and each tin atom exists in a pentagonal bipyramidal geometry. The pentagonal plane is defined by four oxygen atoms, two from the central ligand [Sn? O 2.282(4), 2.473(4)Å] and two from a ‘terminal’ oxalate ligand [Sn? O 2.239(4), 2.210(4)Å], and the fifth site is occupied by a water molecule of crystallization [Sn? O 2.422(4)Å]; the apical sites are filled by the n-butyl groups. Both compounds feature extended hydrogen-bonded networks involving the oxygen atoms of the dianion and the N-bound hydrogen atoms. Crystals of 1 are monoclinic, space group P2₁/n, with cell dimensions a = 13.408(3), b = 22.461(4), c = 13.996(2)Å, β = 100.97(2)^°; full-matrix least-squares refinement on 3305 reflections with I≥2.5σ(I) converged to R = 0.042 and R_w = 0.046. Crystals of 2 are monoclinic, space group P2₁/n, a = 13.729(3), b = 14.694(2), c = 14.889(2)Å, β = 104.83(2)^º; refinement on 2093 reflections converged to R = 0.030 and R_w = 0.031. The two di-n-butylstannates were screened in vitro against the mammary MCF-7 and WiDr colon carcinoma cell lines, and were found to be as active as cisplatin, a clinically used antineoplastic drug.     

Strukturänderungen bei der Reduktion von 9-(Diphenylmethyliden)fluoren mit Natrium-Metall zu Schichten (R2O)Na⊕-verknüpfter Kohlenwasserstoff-Dianionen

Structural Changes on Reduction of 9-(Diphenylmethylidene)fluorene by Sodium Metal to Sheets of (R₂O)Na⊕- Connected Hydrocarbon Dianions The single-crystal structure of 9-(diphenylmethylidene)fluorene (monoclinic, space group P2₁/n, Z = 4) proves a C?C bond length of 135 pm and a twisting of the two Ph rings out of the methylidene-fluorene plane by 70° and 83°. Its reduction in Et₂O solution by a Na mirror under Ar yields dark green crystals with a metallic luster. Their structure, determined in a N₂ flow cooled to 223 K (monoclinic, space group C2/c, Z = 4), reveals sheets of hydrocarbon dianions, connected by sodium(diethylether) links. The Na centers are sixfold coordinated as half-sandwiches to the fluorene benzo rings and threefold allylic to the Ph rings. In the dianion of 9-(diphenyl-methylidene)fluorene, the central C?C bond is stretched by 13 pm to 148 pm length, and the two molecular cyanine-like halves are twisted by 51° relative to each other. Both the contact-ion multiple structures as well as the structural changes on twofold reduction are discussed by way of comparison with literature examples and based on semiempirical calculations.     

The Dianion of Heptalene

Heptalene – a very unstable compound – can be reduced by lithium at ?80° into its dianion. ¹H- and ¹³C-NMR. studies indicate that this dianion, contrary to the neutral molecule, has its π-bonds delocalized. The magnetic field induces in this species a large diamagnetic ring current. The dianion of heptalene is thermally very stable, much more so than the neutral compound. All these observations point to an appreciable stabilization energy associated with the 14°-electron system; this stabilization energy is probably large enough to impose a planar geometry to this dianion.     

A novel synthesis of 4-alkyl-4-(4-methoxyphenyl)cyclohex-2-en-1-ones and the Sceletium alkaloid,o-methyljoubertiamine.

The dianion formed by reduction of (η⁶:η⁶-4,4′-dimethoxybiphenyl)[Cr(CO)₃]₂ reacts with electrophiles such as methyl or ethyl triflate or allyl tosylate at −78 °C followed by CF₃CO₂H and I₂ to form 4-alkyl-4-(4-methoxyphenyl)cyclohex-2-en-1-ones.     

Synthesis,crystal structure and magnetic properties of a new macrocyclic trinuclear CuII-CuII-CuII complex

A new oxamido-bridged trinuclear copper(II) complex [(CuL)₂Cu](ClO₄)₂·0.5H₂O (L?=?the dianion of 2,3-dioxo-5,6,14,15-dibenzo-7,13-bis(ethoxycarbonyl)-1,4,8,12-tetraazacyclotetradeca-7,12-diene) has been synthesized by self-assembly and characterized. X-ray diffraction analysis reveals that the title complex is monoclinic, space group P2₁, with a?=?16.213(5), b?=?9.811(3), c?=?18.802(6)?Å, β?=?96.790(5)°. The central copper(II) ion lies in a distorted octahedral environment. Terminal coppers have square pyramidal coordination geometry. Magnetic measurements show there is strong antiferromagnetic interaction between the central and the terminal Cu(II) ions.     

Crystal Structure, Thermal Stability and Luminescence of Coordination Polymer [Cd（BBP）（p-PDOA）]n

Hydrothermal reaction of Cd（NO3）2·4H2O with bbp and p-PDOAH2 at 140 ℃ yielded a novel 1D cadmium（Ⅱ） coordination polymer, [Cd（bbp）（p-PDOA）]n （bbp=2,6-bis（benzimidazol-2-yl）pyridine, p-PDOA=p-phenylenedioxydiacetate dianion）, in which CdN3O4 pentagonal bipyramids were linked by p-PDOA ligands in a bis-bidentate mode to construct a zigzag chain with the adjacent Cd…Cd distance of 1.14（1） nm, There exists a 2D supramolecular network linked by π-π stacking with a face-to-face distance of 0.35（1） nm between the 2,6-bis（benzimidazol-2-yl） pyridine ligands and hydrogen-bonding interactions （0.27（4） nm）. A 3D supramolecular network was further constructed by these non-covalent interactions between the zippers. The TG/DTG showed that its chain skeleton was thermally stable up to 389 ℃ and the blue fluorescent emission of the complex was determined at 428 nm in a solid state with its long decay lifetime of 7.24 ns.     

Thermal polymerization of N-tert-butylacrylamide in 1,4-dioxane

The kinetics of the thermal polymerization of N-tert-butylacrylamide were investigated in 1,4-dioxane as solvent, in the 65–80°C temperature range. It was found that the overall rate of polymerization which was determined by a gravimetric method is proportional to the 1.9 power of monomer concentration at 70°C. The rate of initiation was determined by ESR spectroscopy using DPPH as an inhibitor, and it was found that the order of initiation rate is 1.8 with respect to monomer concentration at 70°C. The overall activation energy for the thermal polymerization of N-tert-butylacrylamide was found to be 64 ± 9 kJ mol^?1 in the 65–80°C temperature range. The activation energy for the rate of initiation was also determined and it was found to be 90 ± 23 kJ mol^-1.     

Synthesis and Crystal Structure of meso-Δ,Λ-μ-Peroxo-μ-hydroxobis[bis(ethylenediamine)rhodium(III)]trifluoromethane Sulfonate

The reaction of the meso-diol, Δ,Λ-[(en)₂Rh(OH)₂Rh(en)₂]⁴⁺, with aqueous H₂O₂ and 1 equiv. of NaOH at 90° forms the μ-peroxo-μ-hydroxo-bridged species Δ,Λ-[(en)₂Rh(O₂,OH)Rh(en)₂]³⁺ in a yield of ca. 50%. The compound was crystallized as perchlorate and trifluoromethanesulfonate salts. The structure of the latter salt was determined by single-crystal X-ray diffraction. The crystals are triclinic with space group P1 and lattice constants a = 11.895(5), b = 12.491(4), c = 13.053(5) Å, α = 103.98(3), β = 92.59(3), γ = 119.52(6)°. The distances of the metal centres to the bridging peroxo ligand are 1.999(8) and 1.983(6) Å. The O? O distance in the peroxo group is 1.521(14) Å, and the dihedral angle of the Rh? O? O? Rh unit deviates 65° from planarity. The peroxo complex reacts reversibly with acid, and spectrophotometric studies suggest that the reaction involves protonation of the peroxo bridge, with pK_a = 2.70(2) at 25° in 1M NaClO₄.     

Vitamin B13 Complexes of Nickel(II) and Copper(II) with Ethanolamine: Syntheses,Crystal Structures,Spectroscopic and Thermal Studies

Fac‐bis(ethanolamine)orotatonickel(II), [Ni(HOr)(ea)₂] and mer‐bis(ethanolamine)orotatocopper(II) dihydrate, [Cu(HOr)(ea)₂]· 2H₂O were synthesized and characterized by elemental analysis, FT‐IR, UV‐Vis Spectroscopy and thermal analysis. In addition, their solid‐state structures were determined by single crystal X‐ray diffraction studies. Both the fac‐[Ni(HOr)(ea)₂] (1) and mer‐[Cu(HOr)(ea)₂]·2H₂O (2) complexes are isomorphous and crystallize in the triclinic space group . The Ni²⁺ and Cu²⁺ ions are coordinated by two neutral ea ligands and one orotate dianion in a distorted octahedral fashion. The ea ligand acts as a bidentate donor through the amine N and hydroxyl O atoms, while orotate dianion is coordinated through deprotonated N3 pyrimidine atom and carboxylate oxygen atom as a bidentate ligand. Thermal decompositions of the complexes are studied in over the range 20–600 °C on heating in a static air atmosphere.     

Graft copolymerization of hydroxyethyl cellulose with solketal acrylate: Preparation and characterization for moisture absorption application

In this work, we reported the preparation of a novel biomaterial, by graft-polymerization of 2-2-dimethyl-1-3-dioxolan-4-yl methyl acrylate (solketalacrylate, DMDMA) on hydroxyethyl cellulose (HEC) using KPS as initiator. Several experiments were performed to found the optimum conditions for the preparation of this biopolymer, by varying the time of the reaction as well as the initiator and the monomer ratio. Results showed that the highest grafting yield was 25%, obtained after 72?minutes at 65?°C, using THF as solvent. The structure of the grafted copolymer was confirmed by X-ray diffraction patterns which showed, besides the characteristic peaks of HEC at 2θ?=?31.74° and 44.63° a new peak at 2θ?=?30.72° related to an organized structure of the grafted polymer on the HEC backbone. The DSC analysis showed a single glass transition temperature Tg, intermediate between the corresponding values for HEC and neat poly(solketal acrylate). Moreover, the grafted biomaterial presented two-fold more moisture absorption ability by comparison with HEC, making this new synthetic biomaterial highly promising for dryness applications. In our knowledge, the synthesized monomer: 2-2-dimethyl-1-3-dioxolan-4-yl methyl acrylate, (solketal acrylate, DMDMA), has never been grafted on the HEC backbones before that is what makes the novelty of the present work.     

The stereoselectivity of the alkylation of the dianion of ethyl 2-hydroxy-6-methylcyclohexanecarboxylates: Control of stereochemistry at three adjacent stereogenic centers

Yeast reduction of rac-ethyl 2-methyl-6-oxocylohexanecarboxylate (rac- 1 ) yielded selectively (+)-ethyl 2-hydroxy-6-methylcyclohexane carboxylate (+)- 2 (Scheme 1) which has been alkylated with 5-iodo-2-methylbut-2-ene by (the dianion method to furnish the 4-methylbut-3-enyl derivat 3 (Scheme 3)). NaBH₄ reduction of (+)- 1 led to three hydroxy-carboxylates (?)- 2 , (+)- 5 , and (?) -6 (Scheme 4). Allylation of the dianion of (+)- 5 afforded (+)- 7 .     

Die thermische Umlagerung von 2-(Buta-1′,3′-dienyl)-phenolen in 2-Alkyl-2H-chromene; Beispiele für aromatische [1,7a]- und [1,5s]sigmatropische Wasserstoffverschiebungen

2-(1′-cis,3′-cis-)- and 2-(1′-cis,3′-trans-Penta-1′,3′-dienyl)-phenol (cis, cis- 4 and cis, trans- 4 , cf. scheme 1) rearrange thermally at 85–110° via [1,7 a] hydrogen shifts to yield the o-quinomethide 2 (R ? CH₃) which rapidly cyclises to give 2-ethyl-2H-chromene ( 7 ). The trans formation of cis, cis- and cis, trans- 4 into 7 is accompanied by a thermal cis, trans isomerisation of the 3′ double bond in 4. The isomerisation indicates that [1,7 a] hydrogen shifts in 2 compete with the electrocyclic ring closure of 2 . The isomeric phenols, trans, trans- and trans, cis- 4 , are stable at 85–110° but at 190° rearrange also to form 7 . This rearrangement is induced by a thermal cis, trans isomerisation of the 1′ double bond which occurs via [1, 5s] hydrogen shifts. Deuterium labelling experiments show that the chromene 7 is in equilibrium with the o-quinomethide 2 (R ? CH₃), at 210°. Thus, when 2-benzyl-2H-chromene ( 9 ) or 2-(1′-trans,3′-trans,-4′-phenyl-buta1′,3′-dienyl)-phenol (trans, trans- 6 ) is heated in diglyme solution at >200°, an equilibrium mixture of both compounds (～ 55% 9 and 45% 6 ) is obtained.     

Conformational Analysis. XIX properties and reactions of 1,3-oxathianes VIII A 1H NMR conformational study of methyl-substituted derivatives

The addition of thioacetic acid to unsaturated alcohols or acids was utilized to obtain mercaptoalkanols which were condensed with suitable carybonyl compounds to prepare 24 methyl-substituted 1,3-oxathianes. The ¹H NMR spectra of the 1,3-oxathiane products were recorded at 60, 100 and/or 300 MHz and fully analysed. The results are best explained by a chair form which is completely staggered in the C-4? C-5? C-6 moiety ψ₄₅ or (ψ₅₆=60±1°). 1,3-Oxathianes having syn-axial 2,4- (and/or 2,6-) methyl-methyl interactions exist appreciably, if not exclusively, in twist forms. The vicinal coupling constants lead to the conformational free energies of axial methyl groups at C-4, ΔG°=7.4±0.4 kJ mol^?1, and at C-5, ΔG°=3.7±0.3 kJ mol^?1, in good agreement with previous estimates. They also show that both r-4,cis-5,trans-6- and r-4,trans-5,trans-6- trimethyl-1,3-oxathianes greatly favour the chiar form where the methyl group at C-4 is axial. The chair-twist energy parameters are reestimated at ΔH°_CT 27.0 kJ mol^?1, ΔS°_CT 11.6J mol^?1K^?1, and ΔG°_CT(298) 23.5 kJ mol^?1 for a 2,5-twist form.