Bipyridinium ionic liquid-promoted cross-coupling reactions between perfluoroalkyl or pentafluorophenyl halides and aryl iodides

A new room-temperature ionic liquid has been synthesized from 2,2'-bipyridine. This liquid improved the copper-catalyzed cross-coupling reactions between perfluoroalkyl or pentafluorophenyl halides and aryl iodides. Good recyclability using this solvent system was observed.     

Ionic liquid-promoted [3+2]-cycloaddition reactions of nitroformonitrile oxide generated by the cycloreversion of dinitrofuroxan

A new approach to the synthesis of 3-nitroisoxazoles and 3-nitroisoxazolines based on the [3+2]-cycloaddition of nitroformonitrile oxide (NFNO), generated by the cycloreversion of dinitrofuroxan (DNFO), to acetylene and ethylene derivatives, under ionic liquid catalysis is developed. The approach is of a general nature and applicable to cycloaddition reactions with other dipolarophiles.     

Ionic liquid-promoted one-pot oxidative Michael addition of TMSCN to Baylis-Hillman adducts

The first example of ionic liquid-promoted one-pot oxidative conjugate hydrocyanation of Baylis-Hillman adducts with trimethylsilyl cyanide (TMSCN) is reported. The oxidation of Baylis-Hillman adducts with IBX/[bmim]Br or isomerization-oxidation with NaNO₃/[Hmim]HSO₄ systems affords β-ketomethylene compounds or [E]-cinnamaldehydes, respectively. These α,β-unsaturated carbonyl compounds undergo Michael addition with TMSCN in the same vessel to afford the corresponding thermodynamically more stable β-cyanated products. Thermodynamically less stable 1,2-addition products were not formed. The present regioselective reactions are promoted by ionic liquids, which can be recycled easily for further use without any loss of efficiency.     

Unexpected hydroxylamine-induced ring-closure reactions of meso-tetraphenylsecochlorin bisaldehyde

Reaction of meso-tetraphenylsecochlorin bisaldehyde with hydroxylamine results in the formation of the known meso-tetraphenyl-2-nitroporphyrin and the novel meso-tetraphenylimidazolophorphyrin. The products are the result of two diverging pathways of the presumed intermediate monooxime monoaldehyde that are unusual and surprising, but fully rationalized. The structures of both products were confirmed by spectroscopic techniques and single crystal X-ray diffractometry. This reaction represents the first reaction in which a pyrrole in a porphyrin was formally replaced by an imidazole moiety. The optical properties of the free base and metalloimidazoloporphyrin under neutral and acidic conditions are discussed. Further, an alternative synthesis of the imidazoloporphyrin Ni(II) based on meso-tetraphenyl-1-formyl-chlorophin is presented.     

N, N'-二取代二硫代草酰胺与二元胺反应的研究

本文研究了N, N'-二取代二硫代草酰胺与二元胺(乙二胺、1, 3-丙二胺、反-1,2-环己二胺)在二甲基亚矾中的反应。用IR、^1H NMR和四圆衍射法测定了产物的结构。实验结果表明, 反应存在着两种方式, 一种是二元胺的两个氨基反应在同一个硫代酰基的碳原子上(如乙二胺、1, 3-丙二胺)。而另一种由于立体的影响,反应在两个相邻硫代酰基的两个碳原子上(如反-1, 2-环己二胺)。     

Theoretical study of molecular structure and vibrational spectra of 1,4-dihydroxyanthraquinone

Molecular structure and vibrational spectra of 1,4-dihydroxyanthraquinone (1,4-DAQ) are studied theoretically and experimentally. FT-infrared and Raman spectra of 1,4-DAQ are recorded in solid phase in regions of 4000-400 and 3500-100 cm(-1), respectively. The geometry of 1,4-DAQ is optimized by B3LYP and B3PW91 methods, and the most stable structure with C2v point group is found. The harmonic vibration frequencies, infrared intensities, and the Raman scattering activities of the compound are calculated, analyzed, and compared with experimental data. Our calculated frequencies agree well with the experimental results.     

Ionic liquid-promoted regiospecific Friedlander annulation: novel synthesis of quinolines and fused polycyclic quinolines

Several room-temperature ionic liquids (ILs) based on 1-butylimidazolium salts with varying anions were synthesized and evaluated for the preparation of biologically active substituted quinolines and fused polycyclic quinolines using the Friedlander heteroannulation reaction. On screening, 1-butylimidazolium tetrafluoroborate [Hbim]BF4 was found to be the best ionic liquid for the heteroannulation reaction, and the reasons to this effect are well explained. The reactions proceed very well under relatively mild conditions without any added catalyst. The IL acts as a promoter for this regiospecific synthesis and can be recycled. By this green approach, various quinolines were prepared in excellent yields and purity and well-characterized.     

Pyridoxal reactions with amines and aliphatic diamines

Interaction of pyridoxal (3-hydroxy-5-hydroxymethyl-2-methylisonicotinaldehyde) with amines, mono- and disubstituted diamines led to the formation of compounds having in their structure imine, imidazolidine, and pyrimidine moieties. Structure of the obtained compounds was proved by IR data, ¹H NMR spectroscopy, mass spectrometry, and X-ray diffraction analysis.     

Stereoselective diels-alder reactions between 9-alkyl-1,4-dihydronaphthalen-1,4-imines and 2-alkylisoindoles

The Diels-Alder reaction between 9-alkyl-1,4-dihydronaphthalen-1,4-imines ($\text{1}$) and 2-alkylisoindoles ($\text{2}$) occurs in refluxing xylene to give exclusively the exo-endo cyclo-adducts $\text{3}$ ($\text{D}$).     

Ionic liquid-promoted, highly regioselective Heck arylation of electron-rich olefins by aryl halides

Palladium-catalyzed regioselective Heck arylation of the electron-rich olefins, vinyl ethers 1a-d, enamides 1e-g, and allyltrimethylsilane 1h, has been accomplished in imidazolium ionic liquids with a wide range of aryl bromides and iodides instead of the commonly used, but commercially unavailable and expensive, aryl triflates. The reaction proceeded with high efficiency and remarkable regioselectivity without the need for costly or toxic halide scavengers, leading exclusively to substitution by aryl groups of diverse electronic and steric properties at the olefinic carbon alpha to the heteroatom of 1a-g and beta to the heteroatom of 1h. In contrast, the arylation reaction in molecular solvents led to mixtures of regioisomers under similar conditions. Several lines of evidence point to the unique regiocontrol stemming from the ionic environment provided by the ionic liquid that alters the reaction pathway. The chemistry provides a simple, effective method for preparing branched, arylated olefins and contributes to the extension of Heck reaction to a wider range of substrates.     

Kinetic study of electrochemically induced Michael reaction of1,4-dihydroxyanthraquinone with acetylacetone and benzoylacetone

The electrochemical oxidation of 1,4-dihydroxyanthraquinone has been studied in the presence of acetylacetone and benzoylacetone as nucleophiles in a mixture of ethanol/water by means of cyclic voltammetry as a diagnostic technique.The results indicate the participation of electrochemically produced anthraquinone in the Michael addition reaction with acetylacetone and benzoylacetone to form the corresponding new anthraquinone derivatives.On the basis of the EC mechanism,the observed homogeneous rate constants（kobs）of the reaction of anthraquinone with acetylacetone and benzoylacetone were estimated by comparing the experimental cyclic voltammograms with the digitally simulated results.     

Ionic liquid-promoted dehydration of aldoximes: a convenient access to aromatic, heteroaromatic and aliphatic nitriles

A simple and convenient procedure for the synthesis of nitriles by dehydration of aldoximes using an ionic liquid, 1-pentyl-3-methylimidazolium tetrafluoroborate, [pmim]BF₄ under organic solvent-free condition, has been developed. A variety of aromatic, heteroaromatic and aliphatic aldoximes are converted to the corresponding nitriles. The ionic liquid is recovered and reused for subsequent reactions.     

Novel tricyclic diamines 3. Synthesis of 1,4-diazaadamantane

Synthesis of the previously unreported 1,4-diazaadamantane is described. The overall strategy involves complete saturation of a flat, aromatic heterocycle, appropriate functionalization and intramolecular double alkylation. The alkylation takes place via an iminophosphorane under anhydrous conditions, which produced superior results vs. alkylation of the corresponding primary amine.     

Arene-ruthenium complexes of an acyclic thiolate-thioether and tridentate thioether derivatives resulting from ring-closure reactions

The reaction of [(eta(6)-arene)RuCl(2)](2) (arene = C(6)Me(6), 1,4-MeC(6)H(4)CHMe(2)) with a large excess of the dianion of bis(2-mercaptoethyl) sulfide, (HSCH(2)CH(2))(2)S, obtained from deprotonation of the dithiol with freshly prepared NaOMe, gives the deep red, monomeric complexes [(eta(6)-arene)Ru(eta(3)-C(4)H(8)S(3))] (arene = C(6)Me(6) (5), 1,4-MeC(6)H(4)CHMe(2) (6)) in which the dianion is bound to the metal atom through one thioether and two thiolate sulfur atoms. Complex 5 reacts with [(eta(6)-C(6)Me(6))RuCl(2)](2) (4) in a 2:1 mole ratio to give a quantitative yield of the chloride salt of a binuclear cation [((eta(6)-C(6)Me(6))Ru)(2)Cl(mu(2)-eta(2):eta(3)-C(4)H(8)S(3))](+) (7) in which the thiolate sulfur atoms of the [(eta(6)-C(6)Me(6))Ru(eta(3)-C(4)H(8)S(3))] group bridge to a (eta(6)-C(6)Me(6))RuCl unit. This compound is also obtained directly from the reaction of 4 with the dithiolate, if the Ru dimer is used in large excess. The binuclear complex [((eta(6)-C(6)Me(6))Ru)(2)(MeCN)(mu(2)-eta(2):eta(3)-C(4)H(8)S(3))](PF(6))(2).MeCN, (9)(PF(6))(2).MeCN, is obtained by treatment of (7)Cl with NH(4)PF(6) in acetonitrile. Protonation of 5 with HCl gave the mono- and diprotonated derivatives viz. [(eta(6)-C(6)Me(6))Ru(eta(3)-C(4)H(9)S(3))]Cl, (8)Cl, and [(eta(6)-C(6)Me(6))Ru(eta(3)-C(4)H(10)S(3))]Cl(2), (10)Cl(2), respectively. The reaction of 5 with methyl iodide gives both the mono- and di-S-methylated derivatives. Treatment of 5 with dibromoalkanes, Br(CH(2))(n)Br (n = 1-5), effects ring closure to give the (eta(6)-C(6)Me(6))Ru dications containing the trithia mesocyclic zS3 (z = 8-12) ligands, isolated as their PF(6) salts. The X-ray crystal structures of 5, 6, the solvates of (7)Cl and (9)(PF(6))(2), and the trithia mesocyclic Ru complexes (eta(6)-C(6)Me(6))Ru(zS3)(PF(6))(2) (z = 8-11) are reported.     

Site-selective Suzuki-Miyaura reactions of the bis(triflate) of 1,3-dihydroxyanthraquinone

Various aryl-substituted anthraquinones were prepared by palladium(0)-catalyzed Suzuki-Miyaura cross-coupling reactions of the bis(triflate) of 1,3-dihydroxyanthraquinone. A very good site-selectivity in favor of position 1 was observed which can be explained by the electronic influence of the neighboring carbonyl group.     

Wittig approach to carbohydrate-derived vinyl sulfides, new substrates for regiocontrolled ring-closure reactions

Reaction of methyl- and phenylthiomethylidene phosphoranes 1 and 2 with a variety of reducing sugars has been explored. Furano-type carbohydrates afforded with good yields the corresponding open-chain vinyl sulfides, whereas pyrano derivatives produced elimination compounds together with the expected vinyl sulfides, depending on the nature of the protective groups.