Effect of substituents in the propynyl fragment and at the nitrogen atom on the intramolecular cyclization of (3-aryl-2-propynyl)-(4-hydroxy- 2-butynyl)ammonium chlorides and also on the recyclization of the products formed

Cyclization of dialkyl(4-hydroxy-2-butynyl)[3-(α-naphthyl)-2-propynyl]ammonium chlorides using aqueous KOH solution occurs under more rigorous conditions (1:1 ratio of salt to base) than in the case of their 3-phenyl(p-chlorophenyl, alkenyl)-substituted analogs (5:1 ratio of salt to KOH). Similarly, more rigorous conditions are also needed for the cyclization of (4-hydroxy-2-butynyl)-(3-phenyl-2-propynyl)piperazinium- and dicyclohexylammonium chlorides. In addition to the cyclization products - corresponding dialkyl(7-hydroxymethyl)naphtho[1,2-f]isoindolinium or dialkyl-(4-hydroxy-methyl)benzo[f]isoindolinium chlorides, the products of recyclization of these – dialkyl-amino-phenanthro[1,2-c]furan or dialkylaminonaphtho[1,2-c]furan are also formed. The indicated derivatives become the main products of conversion of the starting salts by a change of salt to KOH ratio, 1:2, and with an increase in the time of the reaction. The results obtained can be explained by steric effect and also the lower thermal stability of the obtained naphtho[1,2-f]isoindolinium salt system compared to the analogous benzo[f]isoindolinium systems.     

1-[Hydroxy(sulfonyloxy)iodo]-1H,1H-perfluoroalkanes: Stable, Fluoroalkyl Analogs of Koser's Reagent

1-[Hydroxy(sulfonyloxy)iodo]-1H,1H-perfluoroalkanes 3 [R(f)CH(2)I(OH)OSO(2)R; R = CH(3), CF(3), p-CH(3)C(6)H(4), R(f) = CF(3), C(2)F(5)] can be prepared in two steps from the appropriate iodofluoroalkanes by oxidation with peroxytrifluoroacetic acid and subsequent reaction with TsOH, MsOH, or Me(3)SiOTf. The tosylate derivative 3a reacts with silyl enol ethers under mild conditions to give the respective alpha-(tosyloxy) ketones. A similar reaction of cyclohexene furnishes cis-1,2-bis(tosyloxy)cyclohexane as the major product. Triflates 3c,f react with (trimethylsilyl)arenes under mild conditions to afford the respective (fluoroalkyl) (aryl)iodonium triflates 7, while the analogous reaction with alkynyltrimethylsilanes leads to novel (fluoroalkyl)(alkynyl)iodonium salts 8.     

Novel cation [N(SO2NMe3)2]+ and its synthesis and crystal structure. Dichloride of imido-bis(sulfuric) acid HN(SO2Cl)2. Part 1. Crystal structures of KN(SO2Cl)2.(1/2)CH3CN, KN(SO2Cl)2.(1/6)CH2Cl2, and [PCl4][N(SO2Cl)2

Several salts of bis(chlorosulfonyl)imide HN(SO2Cl)2 (1), namely, two solvates of its potassium salt, KN(SO2Cl)2.(1/2)CH3CN (1K1), KN(SO2Cl)2.(1/6)CH2Cl2 (1K2), and its tetrachlorophosphonium salt, [PCl4][N(SO2Cl)2] (2), were prepared and structurally characterized. The reaction of HN(SO2Cl)2 with Me3N gives the [N(SO2Cl)2]- salt of a novel cation, [N(SO2NMe3)2]+. This cation is analogous to the [HC(SO2NMe3)2]+ cation, but in contrast to the latter, it is fairly stable to hydrolysis. The salt [N(SO2NMe3)2]+[N(SO2Cl)2]- (3) can be converted into salts of other anions by being treated with diluted aqueous solutions of the respective acids, and thus NO3-, Cl-.H2O, SeO3(2-), CH3COO-, HSO4-, (COO)2(2-) salts were prepared. Treatment of 3 with concentrated HNO3 gave the [N(SO2NMe3)2]+ [O2NO-H-ONO2]- salt, and the addition of an HCl-acidified FeCl3 aqueous solution yielded the FeCl4- salt. Methanolysis resulted in the formation of MeOSO3- and [MeOSO2NSO2OMe]- salts. All salts have been characterized by chemical analysis, vibrational spectroscopy, and X-ray structure determinations.     

Intramolecular Cyclization of 1-Benzyl-2-(nitromethylene)pyrrolidines in Triflic Acid

1-Benzyl-2-(nitromethylene)pyrrolidines in triflic acid undergo intramolecular cyclization to afford the corresponding 2,3-dihydro-1H-pyrrolo[1,2-b]isoquinolinium triflates and/or 10-amino-2,3-dihydro-1H-pyrrolo[1,2-b]isoquinolinium triflates, depending on the nature of the aromatic substituent. Structures of products and reaction mechanisms are discussed.     

2-单核和双核茂铁基-1,3-二烷基苯并咪唑盐的合成、结构及性质研究

以2-二茂铁基苯并咪唑(2)为原料,合成了1-甲基-2-二茂铁基-3-乙基苯并咪唑碘盐(4)和六氟磷酸盐(5);甲酰化的2,2-双二茂铁基丙烷(6)与邻苯二胺在甲醇作溶剂,回流,碘催化下反应,得到2-[1’-(2-二茂铁基丙烷-2-基)二茂铁-1-基]苯并咪唑(7),以7为原料合成了1-甲基-2-[1’-(2-二茂铁基丙烷-2-基)二茂铁-1-基]-3-乙基苯并咪唑碘盐(9)和六氟磷酸盐(10).电化学分析表明所得的盐化合物中,与苯并咪唑阳离子直接相连的二茂铁的氧化电位相对2和7均产生了较大正移.对化合物4的单晶结构进行了解析,晶体结构中存在π-π堆积.UV-Vis吸收光谱表明所得盐化合物具有光致电荷迁移现象.DSC-TG(差示扫描量热-热重)测试表明碘盐4对高氯酸铵(AP)热分解有较好催化效果.     

Synthesis of Alkyl 6-(2-Alkoxy-2-oxoethyl)dibenzo[d,f][1,3]dioxepine-6-carboxylates from Stabilized Phosphorus Ylides

Protonation of the highly reactive 1:1 intermediates, produced in the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates, by biphenyl-2,2′ -diol leads to vinyltriphenylphosphonium salts, which undergo a Michael addition reaction with a conjugate base to produce the corresponding stabilized phosphorus ylides. Magnesium oxide powder was found to catalyze the conversion of the stabilized phosphorus ylides to alkyl 6-(2-alkoxy-2-oxoethyl)dibenzo[d,f][1,3]dioxepine-6-carboxylates in solvent-free conditions under microwave (0.5 KW, 3 min) and thermal (90 °C, 60 min) conditions.     

Total synthesis of (+/-)-magnofargesin

[reaction: see text] A convenient method for the preparation of 2,5-dihydrofurans by using the chemistry of alkynyl(phenyl)iodonium salts is reported. Treatment of 3-alkoxy-1-alkynyl(phenyl)iodonium triflates with sodium benzenesulfinate generates an alkylidenecarbene, which undergoes [1,5]-C-H insertion to form 2-substituted 4-benzenesulfonyl-2,5-dihydrofurans in reasonable yield. These cyclic vinyl sulfones are functionalized in such a way as to make them useful starting materials for the preparation of lignans. The application of this methodology to the first total synthesis of (+/-)-magnofargesin is disclosed.     

Reactions of pyrazinium salts with phenols:from σ<Superscript>H</Superscript>-adducts to S<Subscript>N</Subscript><Superscript>H</Superscript>products and transformations into benzo[<Emphasis Type="Italic">b</Emphasis>]furans

The reaction of 5-(het)aryl-2,3-dicyano-1-ethylpyrazinium salts with phenol derivatives affords relatively stable dihydropyrazines, whereas the reactions of 6-(het)aryl-1,2,5-oxadiazolo[3,4-b]pyrazin-4-ium protic salts, depending on the phenol structure, result in products of nucleophilic substitution of hydrogen or open-chain transformation products: benzo[b]furan-substituted derivatives. The crystallographic data on the spatial structure of all types of the synthesized products were obtained.     

Structure of the decamethyl titanocene cation,a metallocene with two agostic C-h bonds,and its interaction with fluorocarbons

The tetraphenylborate salt of the decamethyl titanocene cation, [Cp*2Ti][BPh4] (1, Cp* = C5Me5), was prepared by reaction of Cp*2TiH with [Cp2Fe][BPh4] and by reaction of Cp*2TiMe with [PhNMe2H][BPh4]. The crystal structure of 1 shows that the Cp*2Ti cation has a bent metallocene structure with agostic interactions with the metal center of two adjacent methyl groups on one of the Cp* ligands. Compound 1 reacts readily with THF to give the adduct [Cp*2Ti(THF)][BPh4] (2). In fluorobenzene, 1 forms the eta1-fluorobenzene adduct [Cp*2Ti(eta1-FC6H5)][BPh4] (3), which was structurally characterized. In contrast to the thermal stability of 3, addition of alpha,alpha,alpha-trifluorotoluene to either 1 or 2 results in C-F activation to give Cp*2TiF2 and PhCF2CF2Ph as the main products. This reactivity toward benzylic C-F bonds is also reflected in the reactivity toward the fluorinated borate anions [B(C6F5)4]- and {B(3,5-(CF3)2C6H3]4}-: reaction of Cp*2TiMe with their [PhNMe2H]+ salts results in a stable complex for the former anion, whereas rapid C-F activation is observed for the latter.     

Thermal and light-induced spin-crossover in salts of the heptadentate complex [tris(4-{pyrazol-3-yl}-3-aza-3-butenyl)amine]iron(ii)

The syntheses of [FeL][BF(4)](2).H(2)O, [FeL][ClO(4)](2).H(2)O, [FeL][NO(3)](2).CH(3)NO(2) and [FeL][CF(3)SO(3)](2) (L = tris(4-{pyrazol-3-yl}-3-aza-3-butenyl)amine) are described. The isostructural BF(4)(-) and ClO(4)(-) salts are high-spin between 5-300 K, while the other two compounds are high-spin at room temperature but undergo gradual high-->low spin transitions upon cooling. For [FeL][NO(3)](2) this transition is centred at 139 K and proceeds to near-completeness, while for [FeL][CF(3)SO(3)](2) it is centred at 144 K and only proceeds to 50% conversion. The CF(3)SO(3)(-) salt also undergoes spin-crossover centred at 200 K in (CD(3))(2)CO solution, and exhibits dynamic inversion of its helical ligand conformation. All these compounds except the triflate salt have been crystallographically characterised, and show capped trigonal antiprismatic [6 + 1] coordination geometries. The NO(3)(-) and CF(3)SO(3)(-) salts undergo quantitative conversion to trapped, high-spin excited states upon irradiation with a green laser at 10 K (the LIESST effect; LIESST = Light-Induced Excited Spin State Trapping). The thermal stabilities of their LIESST excited states (T(LIESST) = 80-82 K) resemble those found for iron(ii) complexes of bidentate N-heterocyclic ligands. Hence, the LIESST properties of [FeL](2+) are those of a complex of three rigid bidentate domains linked by a flexible spacer, rather than of a single encapsulating podand.     

Remarkably facile solvolyses of triflates via carbocationic processes in dimethyl sulfoxide

A number of triflates have been shown to undergo clean pseudo-first-order solvolysis reactions in DMSO-d(6) to give products derived from carbocationic intermediates. Thus, t-BuCH(OTf)CO-t-Bu (5) and t-BuCH(2)OTf (9) react readily in DMSO-d(6) at 25 degrees C to give a rearranged oxosulfonium salts, and subsequent alkene products where methyl migration to the incipient cationic center occurs. t-BuCH(OTf)CO(2)CH(3) (14) gives analogous rearranged products, and 1-methylcyclopropyl triflate (21) gives a ring-opened allylic oxosulfonium salt. These triflates react primarily via k(Delta) pathways. 6-Methylbicyclo[3.1.0]hex-6-yl triflate (23), bicyclo[2.2.1hept-1-yl triflate (24), 1,6-methano[10]annulen-11-yl triflate (25), (CH(3))(2)C(OTf)CO(2)CH(3) (26), and (CH(3))(2)CCN(OTf) (29) all react in DMSO-d(6) to give carbocation-derived products. PhCH(OTf)CF(3) (33) and substituted analogues also react readily in DMSO-d(6), and the Hammett rho(+) value is -3.7. This suggests a "borderline" mechanism where the transition state has substantial charge development. The primary feature of these solvolyses is the high reactivity of all of these triflates in DMSO-d(6). Thus, these triflates are all more reactive in DMSO-d(6) than in HOAc, and for most, rates are faster than in CF(3)CH(2)OH. Triflates 5, 21, 29, and 33 are 10(8)-10(9) times more reactive in DMSO-d(6) than the corresponding mesylates. It is suggested that the decreased need for electrophilic solvation of triflate anion, and the high cation solvating ability of DMSO, are the reasons for the high triflate reactivity in DMSO-d(6).     

Intramolecular cyclization of beta-amino and beta-ammonio radicals: a new synthetic route to the 1-azabicyclo

Treatment of 1-(2-phenylselenoethyl)-1,2,5,6-tetrahydropyridine (15) with tributyltin hydride affords only the product of reduction, demonstrating the reluctance of the 5-hexenyl radical 9 to undergo ring closure. When the nature of the radical is modified, either by introduction of an ester group at C4 or via its quaternary ammonium salt, cyclization occurs readily; while the radical 52 gives an excellent yield of 1-methyl-1-azoniabicyclo[3.2.1.]octyl bromide (55) uncontaminated with the product of reduction, the bicyclic product from 21 is accompanied by some reduced material. Production of the unwanted alkene can be eliminated in the latter by recourse to the quaternary ammonium ester 1-(2-bromoethyl)-4-carbethoxy-1-methyl-1,2,5,6-tetrahydropyridinium bromide (35) which, when exposed to tributyltin hydride, affords a 1:1 endo/exo mixture of 4-carbethoxy-1-methyl-1-azoniabicyclo[3.2.1]octyl bromide (37) exclusively. These results support the demonstration of the powerful polar effect of an ester function when attached to the double bond of a 5-hexenyl system, a property which can be exploited in the case of the radical 58. Treatment of the precursor, 1-(2-bromoethyl)-3-carbethoxy-1-methyl-3-pyrrolinium bromide (60), with tributyltin hydride generates 58 which is found to cyclize with high regioselectivity, affording a convenient high-yielding synthesis of the endo/exo isomers of 3-carbethoxy-1-methyl-1-azoniabicyclo[2.2.1]heptyl bromide 57. The isomeric bicyclo[2.2.1]heptyl ester 63 was not detected. These observations are in accordance with predictions based upon frontier molecular orbital considerations.     

Pressure effect on bulk weak ferromagnets: (BDH-TTP)[M(isoq)2(NCS)4] (M = Cr(III), Fe(III); isoq = Isoquinoline)

The pressure dependence of the magnetic properties of weak ferromagnets (BDH-TTP)[M(isoq)2(NCS)4] [BDH-TTP = 2,5-bis(1',3'-dithiolan-2'-ylidene)-1,3,4,6-tetrathiapentalene; M = Cr, Fe; isoq = isoquinoline] is discussed. These salts form two-dimensional magnetic sheets, where ferrimagnetic chains of donor cation radical (S = 1/2) and anion [S = 3/2 (Cr), 5/2 (Fe)] are antiferromagnetically connected by weak donor-donor and anion-anion interchain S...S contacts. Under ambient pressure, both the Cr and Fe salts undergo a weak ferromagnetic transition at Tc = 7.6 K, below which a spontaneous magnetization emerges along the direction perpendicular to the sheets. The application of the pressure elevates the transition temperatures up to 16.6 and 11.6 K at 9 kbar for M = Cr and Fe, respectively. As the pressure increases, the remanent magnetization M(r) decreases, whose pressure dependence for the Cr salt is larger than that for the Fe salt. This difference indicates that the spin-canting angle of the Cr salt is reduced because of the increase of antiferromagnetic interaction by applied pressure, in contrast to the Fe salt, where single-ion anisotropy contributes less. The quantitative analysis of the magnetization curves of the Cr salt using the mean-field approximation reveals that the intermolecular exchange interaction increases as the pressure increases, among which the interchain anion-anion interaction has the highest pressure sensitivity. This result is consistent with the temperature dependence of the crystal structure showing that the thermal contraction in the distances of interchain anion-anion S...S contacts is the most remarkable in intrachain S...S contacts. The large pressure dependence of the transition temperature of these salts is therefore explained as a result of the fact that the interchain interactions, the anion-anion interaction in particular, are strengthened by applied pressure.     

Silica Gel Catalyzed Conversion of Dialkyl 2-(2-Hydroxy-1-naphthyl)-3-(1,1,1-triphenyl-λ 5 -phosphanylidene) Succinates to Alkyl 3-Oxo-3 H -benzo[ f ]chromene-1-carboxylates in Solvent-free Conditions

Protonation of the highly reactive 1:1 intermediates produced in the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates by 2-hydroxynaphthalene leads to vinyltriphenylphosphonium salts, which undergo aromatic electrophilic substitution reaction with conjugate base to produce dialkyl 2-(1-hydroxy-2-naphthyl)-3-(1,1,1-triphenyl- u 5 -phosphanylidene) succinates. Silica gel was found to catalyze conversion of dialkyl 2-(1-hydroxy-2-naphthyl)-3-(1,1,1-triphenyl- u 5 -phosphanylidene) succinates to alkyl 3-oxo-3H-benzo[f]chromene-1-carboxylates in solvent-free conditions at 60°;C in fairly good yields.     

Formation of p-phenylenediamine-crown ether-[PMo12O40]4- salts

Electron transfer from the electron donor of p-phenylenediamine (PPD) to the electron acceptor of (H+)3[PMo12O40]3- forms a one-electron-reduced Keggin cluster of [PMo12O40]4-, bearing a S = 1/2 spin, while proton transfer from the proton donor of (H+)3[PMo12O40]3- to the proton acceptor of PPD yielded mono- and diprotonated cations of 4-aminoanilinium (HPPD+) and p-phenylenediammonium (H2PPD2+). By introduction of crown ether receptors during the crystallization process, supramolecular cations of (HPPD+)(crown ethers) and/or (H2PPD2+)(crown ethers) were successfully introduced into three new alpha-[PMo12O40]4- salts of (H2PPD2+)2([12]crown-4)4[PMo12O40]4- (1), (HPPD+)4([15]crown-5)4[PMo12O40]4- (2), and (HPPD+)2(H2PPD2+)([18]crown-6)4[PMo12O40]4- (3) as the countercation. The protonated states of PPD and molecular-assembly structures of the supramolecular cations depended on the size of the crown ethers. In salt 3, a novel mixed-protonated state of HPPD+ and H2PPD2+ was confirmed to be complexed in the cation structure. According to the changes in the cation structures, the anion arrangements were modulated from those of the two-dimensional layer for salt 1 to the isolated cluster for salts 2 and 3. The temperature-dependent magnetic susceptibilities of salts 1-3 were consistent with the isolated spin arrangements of [PMo12O40]4-. The electronic spectra of salts 1-3 indicated the intervalence optical transition from pentavalent Mo(V) to hexavalent Mo(VI) ions within the [PMo12O40]4- cluster. Temperature-dependent electron spin resonance spectra of salt 2 revealed the delocalization-localization transition of the S = 1/2 spin at 60 K. The spin on the [PMo12O40]4- cluster was localized on a specific Mo(V) site below 60 K, which was thermally activated with an activation energy of 0.015 eV.     

Complex [Ag(PPh3)4][2-B10H9NH3 · 2DMF]: Synthesis and Structure

Russian Journal of Coordination Chemistry - The formation of complex salt [Ag(PPh3)4][2-B10H9NH3 ? 2DMF] (I) by the reaction of the salts of the [2-B10H9NH3]– anion with [Ag(PPh3)4]NO3...     

Palladium-catalyzed allylalkynylation of benzynes: a highly efficient route to substituted 1-allyl-2-alkynylbenzenes

Benzynes, generated in situ from 2-(trimethylsilyl)aryl triflates and cesium fluoride, undergo allylalkynylation with allylic chlorides and alkynylstannanes in the presence of palladium catalyst to give 1-allyl-2-alkynylbenzenes in good to excellent yields. [reaction: see text]     

A Direct Route to C-Vinylaziridines: Reaction of N-Sufonylimines with Allylic Ylides under Phase-Transfer Conditions or with Preformed Ylides at Low Temperature

Allylic sulfonium salts 3, 5, 7, 11, 12, 13, and arsonium salt 14 react with aromatic, heteroaromatic, and alpha,beta-unsaturated N-sulfonylimines under solid-liquid phase-transfer conditions in the presence of KOH at room temperature to produce, respectively, vinyl-, (beta-phenylvinyl)-, and [beta-(trimethylsilyl)vinyl]aziridines in excellent yields within several minutes. In some cases, pyrroline compound 9 is obtained as a minor product. This aziridination reaction has also been carried out with preformed ylides, generated from sulfonium salts 3, 7, arsonium salt 14, and telluronium salts 15, 16 with a base in THF at -78 degrees C. In most examples, quantitative yields were achieved. However, the trans/cis selectivity of the reaction was not high in either case. A semistable allylic sulfonium ylide, i.e., dimethylsulfonium 3-(trimethylsilyl)allylide, was found to not undergo an expected [2,3]-sigma-rearrangement and so can also be used in this reaction.     

Selective palladium-catalyzed cocyclotrimerization of arynes with dimethyl acetylenedicarboxylate: A versatile method for the synthesis of polycyclic aromatic hydrocarbons

Benzyne (1a) and the substituted derivatives 4,5-difluorobenzyne (1b) and 3-methoxybenzyne (2) undergo chemoselective palladium-catalyzed [2 + 2 + 2]-cocyclotrimerization with dimethyl acetylenedicarboxylate (DMAD) to afford the corresponding phenanthrenes and/or naphthalenes. The major products are phenanthrenes if Pd(PPh(3))(4) is used as the catalyst, naphthalenes if Pd(2)(dba)(3) is used. When the method is applied to polycyclic arynes 3-6, which are generated from the corresponding o-trimethylsilylaryl triflates, the same reactivity pattern is observed: the reaction can be selectively directed either toward the cocyclization of one molecule of aryne and two molecules of alkyne or to the reaction of two molecules of aryne with one molecule of alkyne, by appropriate choice of the palladium catalyst. The synthesis of polycyclic aromatic compounds 33-39 using this methodology is reported.     

Synthesis,crystal structures,and properties of 5-(het)aryl-3-cyano-1-ethyl-2(1<Emphasis Type="Italic">H</Emphasis>)-pyrazinones

A simple method for the synthesis of 5-(het)aryl-3-cyano-1-ethyl-2(1H)-pyrazinones was proposed. The method is based on the hydrolysis of the corresponding 2,3-dicyanopyrazinium salts. The spectral properties of pyrazinones were studied and their crystallographic investigation was carried out. The possibility of introduction of 5-(het)aryl-3-cyano-1-ethyl-2(1H)-pyrazinones into the [2+4] cycloaddition under the microwave activation conditions was shown.