Copper-Catalyzed Multicomponent Coupling Reaction of Primary Aromatic Amines, Rongalite, and Alkynes: Access to N-Aryl Propargylamines.

In this work, a practical copper-catalyzed multicomponent coupling reaction of primary aromatic amines, rongalite, and alkynes for the direct synthesis of N-aryl propargylamines has been developed. This method could overcome the substrate limitation in A3 coupling reactions of primary aromatic amines, formaldehyde, and alkynes. Mechanistic studies revealed that rongalite acts as not only the active C1 unit but also the accelerator to activate the in situ-generated N-arylmethanimines for the coupling reaction with alkynes. This coupling reaction is highly efficient and features a broad substrate scope, as well as utility with scale-up synthesis and converting the corresponding product N-aryl propargylamines into useful heterocyclic skeletons.

Synthesis of primary propargylic alcohols from terminal alkynes using rongalite as the C1 unit.

Here, an efficient leaving group-activated methylene alcohol strategy for the preparation of primary propargyl alcohols from terminal alkynes by employing the bulk industrial product rongalite as the C1 unit has been described. The reaction avoids the low-temperature reaction conditions and inconvenient lithium reagents required for the classical method of preparing primary propargylic alcohols. Preliminary mechanistic studies showed that the reaction may not proceed via formaldehyde intermediates, but through the direct nucleophilic attack of the terminal alkyne on the carbon atom of rongalite by activation through SO2- as a leaving group.

Metal-promoted intermolecular electron transfer in tetrathiafulvalene-thiacalix[4]arene conjugates and tetrachlorobenzoquinone.

In this work, two series of tetrathiafulvalene (TTF) and thiacalix[4]arene (TCA) conjugates (TTF-TCA) were designed by CuAAC click reactions. The results obtained from NMR and (1)H NMR NOE indicated that their conformations of thiacalix[4]arene framework may prefer to 1,3-alternate. The cyclic voltammograms of four TTF-TCA compounds containing electroactive TTF units were provided. Meanwhile, their intermolecular electron-transfer (ET) behaviors with tetrachlorobenzoquinone (Q) mediated by different metal ions, Sc(3+), Pb(2+), Ag(+), Cd(2+), and Zn(2+), in CH3CN-CH2Cl2 (V/V = 1:1) solution were studied and analyzed via UV-vis spectroscopy. It was determined that intermolecular ET between each TTF-TCA and Q ensemble was not observed without introduction of the metal ions mentioned above. The added specified metal ions most likely induced the intermolecular ET between TTF-TCA and Q ensemble, and the effects of Sc(3+) functions were the most imperative. The intermolecular ET also proved to be reliant on the structure of TTF-TCA, where TTF-TCA 7a and 7b were more effective than TTF-TCA 6a and 6b. The difference may be credited to TTF-TCA 7a or 7b possessing two independent TTF pendants and providing a more synergic coordination among the TTF radical cation and Q radical anion with a metal ion.

A new two-dimensional manganese(II) coordination polymer based on thiophene-3,4-dicarboxylic acid.

A novel manganese coordination polymer, poly[(µ5-thiophene-3,4-dicarboxylato)manganese(II)], [Mn(C6H2O4S)]n, was synthesized hydrothermally using 3,4-thiophenedicarboxylate (3,4-tdc(2-)) as the organic linker. The asymmetric unit of the complex contains an Mn(2+) cation and one half of a deprotonated 3,4-tdc(2-) anion, both residing on a twofold axis. Each Mn(2+) centre is six-coordinated by O atoms of bridging/chelating carboxylate groups from five 3,4-tdc(2-) anions, forming a slightly distorted octahedron. The Mn(2+) centres are bridged by 3,4-tdc(2-) anions to give an infinite two-dimensional layer which incorporates one-dimensional Mn-O gridlike chains, and in which the 3,4-tdc(2-) anion adopts a novel hexadentate chelating and µ5-bridging coordination mode. The fully deprotonated 3,4-tdc(2-) anion exhibits unexpected efficiency as a ligand towards the Mn(2+) centres, which it coordinates through all of its carboxylate O atoms to provide the novel coordination mode. The IR spectrum of the complex is also reported.

4-Bromo-5-[(2-bromo-ethyl)-sulfanyl]-1,3-dithiole-2-thione.

The title compound, C(5)H(4)Br(2)S(4), consists of a statistically planar, 4-bromo-1,3-dithiole-2-thione unit [maximum deviation from the ring plane 0.001 (2) Å], with a bromo-ethyl-sulfanyl substituent in the 5-position. In the crystal structure, weak inter-molecular S⋯S [3.438 (15) and 3.522 (15) Å] and S⋯Br [3.422 (14) and 3.498 (14) Å] inter-actions generate a three-dimensional supra-molecular architecture.

Bis(1,3,4-thia-diazol-2-yl) disulfide.

The title compound, C(4)H(2)N(4)S(4), lies about a twofold rotation axis situated at the mid-point of the central S-S bond. Each of two thia-diazole rings is essentially planar, with an rms deviation for the unique thia-diazole ring plane of 0.0019 (7) Å. C-H⋯N hydrogen bonds link adjacent mol-ecules, forming zigzag chains along the c axis. In addition, these chains are connected by inter-molecular S⋯S inter-actions [S⋯S = 3.5153 (11) Å] , forming corrugated sheets, and further fabricate a three-dimensional supra-molecular structure by inter-molecular N⋯S contacts [S⋯N = 3.1941 (17) Å].

3-(2-Thioxo-1,3-dithiol-4-ylsulfan-yl)-propane-nitrile.

The title compound, C(6)H(5)NS(4), consists of a planar 2-thioxo-1,3-dithiol-4-ylsulfanyl unit [maximum deviation from the ring plane = 0.0325 (2) Å], with a cyano-ethyl-sulfanyl substituent in the 4-position. In the crystal structure, weak inter-molecular C-H⋯S hydrogen bonds together with S⋯N inter-actions [3.260 (5) Å] form two-dimensional layers in the bc plane.

Bis(calixcrown)tetrathiafulvalene receptors.

A new class of electroactive receptors has been synthesized, built by covalent association of five subunits: two calixarene platforms for spatial organization, two polyether 3D cavities for cation binding, and one electroactive TTF unit to probe the complexation event. Sodium complexation induces rigidification of the molecular assembly, as shown by 1H NMR titration and single-crystal X-ray crystallographic studies on free receptor 14 and a corresponding complex with two bound sodium atoms per receptor (15-(NaPF6)2). The calixarene units in these receptors change from a pinched cone conformation in the free ligand to a symmetrical cone in the complex. Cyclovoltammetric studies validated the electrochemical recognition concept of these five-member assemblies.

Bis-calix[4]arenes bridged by an electroactive tetrathiafulvalene unit.

Syntheses of the first bis-calixarenes systems bridged by a tetrathiafulvalene (TTF) framework 5a,b have been carried out in good yields through triethyl phosphite-mediated dechalcogenation-dimerizations of the corresponding 1,3-dithiole-2-(thi)ones 3 or 4. X-ray structures of the calix[4]arene-TTF-calix[4]arene assembly 5b and of the calix[4]arene-thione intermediate 3b are analyzed and confirm the cone conformations adopted by the calix[4]arene parts, as it is also observed by (1)H NMR analysis of these systems. The solid-state organization in 5b leads to alternate layers of calixarene and TTF units. The cyclic voltammograms of 5a,b show as expected a two-step redox behavior but display a CV deformation for the second redox process.

Spectroscopic behavior on the formation complex of three double-armed calix[4]arene derivatives with lanthanoid nitrates in acetonitrile.

The complexation spectroscopic behavior of three p-tert-butylcalix[4]arene Schiff bases i.e. 5,11,17,23-tetra-tert-butyl-25,27-bis[2-[N-(3-nitrobenzylidene)amino]ethoxy]-26,28-dihydroxycalix[4]arene (1), 5,11,17,23-tetra-tert-butyl-25,27-bis[2-[N-(2-hydroxybenzylidene)amino]ethoxy]-26,28-dihydroxycalix[4]arene (2), and 5,11,17,23-tetra-tert-butyl-25,27-bis[2-[N-(2-hydroxy-3-methoxybenzylidene)amino]ethoxy]-26,28-dihydroxycalix[4]arene (3) with lanthanoid nitrates (Tb3+ and Eu3+) has been investigated in anhydrous acetonitrile at 25 degrees C by using UV-vis and FT-IR as well as fluorescence spectra. The results obtained indicated that the spectroscopic behavior of compounds 1-2 upon complexation with lanthanoid ions did not show any significant larger difference in comparison with free compounds 1 and 2, which may be contributed to the poor binding ability. Contrary to compounds 1 and 2, the lower rim functional groups in compound 3 can form two large pi electron conjugate system with lanthanide ion and encapsulate lanthanide ions tightly, displaying the novel spectroscopic behavior upon complexation with lanthanide ions. As compared with compound 3, the formation complexes of compound 3 with Tb3+ and Eu3+ showed new broad intense absorption at 398 nm, respectively, and IR spectra showed that O-H stretching vibration at 3413.40 cm(-1) displayed a large drop. It is interestingly noted that the narrow emission line spectra were observed only for 3 complex with Tb3+, but did not for 3-Eu3+ complex. In the 3-Eu3+ complex, the broad-band emission at lambda(max) = 534 nm was obtained at the excitation of 398 nm. The spectroscopic behavior of three calix[4]arene derivatives upon complexation with lanthanoids was discussed from the relationship between the host structure and the properties of guest lanthanide ions.