Synthesis and photochemistry of beta,beta'-di(2-furyl)-substituted o-divinylbenzenes: intra- and/or intermolecular cycloaddition as an effect of annelation

New heteroaryl-substituted o-divinylbenzenes, 2,2'-(1,2-phenylenedivinylene)difuran (9), 2,2'-(1,2-phenylenedivinylene)bisbenzo[b]furan (10), and 2,2'-(1,2-phenylenedivinylene)bisnaphtho[2,1-b]furan (11), were prepared and irradiated at various concentrations; intramolecular photocycloaddition and intermolecular [2+2] twofold photoaddition reactions took place to give bicyclo[3.2.1]octadiene derivatives 12-14 and cyclophane derivatives 15-17, respectively. Compound 11 was the most selective of these o-divinylbenzenes, which, owing to pi-pi intra- or intermolecular complexation, gave only the exo-bicyclo[3.2.1]octadiene derivative 14 at low concentrations, and only the cyclophane derivative 17 at high concentrations.     

A new platinum-osmium alkyne complex from the reaction of Pt2Os4(CO)18 with PhC ≡ CPh: The synthesis,characterization, and crystal structure of Pt2Os4(CO)8 (μ3-PhC2Ph)3(μ4-PhC2Ph)

The new platinum-osmium alkyne cluster complex Pt₂Os₄(CO)₈(₃-PhC₂Ph)₃ ( ₄-PhC₂Ph),2, was obtained from the reaction of Pt₂Os₄(CO)₁₈,1b, with PhC₂Ph and was characterized by IR.¹H NMR and single-crystal X-ray diffraction analyses. The cluster of compound2 consists of an osmium capped Pt₂Os₃ square pyramid. It aLso contains three triply bridging and one quadruply bridging diphenylacetylene ligands. Crystal data for2: space group PI,a = 12.530(2) Å,b = 21.565(4) Å,c = 11.284(2) Å, = 100.31(2), = 111.89(1), = 76.78(2),Z = 2, 3879 reflections,R = 0.032.     

Synthesis and oxidation of 1-hydroxy-3(2)-imidazoline-derived enaminones

Interaction of 1-hydroxy-3-imidazoline and 3-imidazoline 3-oxide derivatives with esters in the presence of LDA gives enaminones, derivatives of imidazolidine. Oxidation of these compounds with MnO₂ leads to4H-imidazoleN-oxides, oxidative dirnerization products, or stable nitroxyl radicals, depending on the structure of the initial compound.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1789–1795, July, 1996.     

Intramolecular Alkyne Coupling in the Reaction of 1,8-bis(phenylethynyl)naphthalene with Pt2Ru4(CO)18

The reaction of Pt₂Ru₄(CO)₁₈, 1 with 1,8-bis(phenylethynyl)naphthalene, 2 has yielded two metal carbonyl cluster complexes: Ru₂(CO)₆[- ²-C₁₀H₆C₄Ph₂], 3 (60% yield) and Ru₂Pt(CO)₆[- ²-C₁₀H₆C₄Ph₂]₂, 4 (8% yield). Both compounds were characterized by a single crystal X-ray diffraction analysis. Both products were formed as a result of fragmentation of the Pt₂Ru₄ cluster of 1. Compound 3 contains two ruthenium atoms. They are bridged by a tricyclic C₁₀H₆C₄Ph₂ ligand formed by the coupling of the two -carbon atoms of the alkyne groups. The -carbon atoms of the alkynes are -bonded to one of the ruthenium atoms to form a metallacycle and this entire group is -bonded to the second ruthenium atom. Compound 4 contains two ruthenium atoms with a platinum atom between them. This molecule contains two tricyclic C₁₀H₆C₄Ph₂ ligands similar to that in 3, and two metallacycles formed by coordination of the -carbon atoms of both ligands to the platinum atom. One ligand is -bonded to each of the ruthenium atoms.     

Features of the photochromic behavior of spiroanthrooxazine in solutions

The photochromic properties of 1,3,3-trimethylspiro[indolin-2,3-3H-anthraceno[2,1-b][1,4]-oxazine] (SAO) in solutions of different polarity [n-BuOH and petroleum ether (PETh)] were studied. It was established that the quantum yield of the photocoloration AB and the energy of activation of the thermal decolorization E_a in the PETh depend on the temperature; this is not the case in n-BuOH. The luminescence properties of SAO were investigated. It was found that the spectrum of the excitation of the luminescence in PETh depends on the temperature. These features, as well as the slower thermal decolorization of the colored form of SAO in PETh by comparison with the solutions in n-BuOH, are explained by the presence of dimers of the SAO molecules in nonpolar media in the temperature range investigated (77–300 K), whereas the SAO molecules already occur in the monomeric state at 150 K in the polar n-BuOH.N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, 117977 Moscow. Branch of the Institute of the Physics of Solids and Semiconductors, Academy of Sciences of Belarus, 211177 Vitebsk. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 93–98, January, 1992.     

Electrochemical dimerization of phenacyl bromides N-acylhydrazones—a new way to 1-N-acylamino-2,5-diaryl-pyrroles

Cathodic reduction of phenacyl bromides N-acyl hydrazones lead to dimeric 1,4-diaryl-1,4-butanedione di-N-acylhydrazones, which give the corresponding 1-N-acylamino-2,5-diarylpyrroles in good yields.     

How good is CuAAC “click” chemistry for polymer coupling reactions?

¹H NMR and SEC analyses are used to investigate the overall efficiency of Copper Catalyzed Azide Alkyne Cycloaddition (CuAAC) “click” coupling reactions between alkyne‐ and azide‐terminated polymers using polystyrene as a model. Quantitative convolution modeling of the entire molecular weight distribution is applied to characterize the outcomes of the functional polymer synthesis reactions (i.e., by atom transfer radical polymerization), as well as the CuAAC coupling reaction. Incomplete functionality of the azide‐terminated polystyrene (∼92%) proves to be the largest factor compromising the efficacy of the CuAAC coupling reaction and is attributed primarily to the loss of terminal bromide functionality during its synthesis. The efficiency of the S_N2 reaction converting bromide to azide was found to be about 99%. After taking into account the influence of non‐functional polymer, we find that, under the reaction conditions used, the efficiency of the CuAAC coupling reaction determined from both techniques is about 94%. These inefficiencies compromise the fidelity and potential utility of CuAAC coupling reactions for the synthesis of hierarchically structured polymers. While CuAAC efficiency is expected to depend on the specific reaction conditions used, the framework described for determining reaction efficiency does provide a means for ultimately optimizing the reaction conditions for CuAAC coupling reactions. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 75–84     

Concurrent Covalent and Supramolecular Polymerization

Covalent and supramolecular polymerizations, both of which offer their own unique advantages, have emerged as popular strategies for making artificial materials. Herein, we describe a concurrent covalent and supramolecular polymerization strategy—namely, one which utilizes 1) a bis‐azide‐functionalized diazaperopyrenium dication that undergoes polymeriation covalently with a bis‐alkyne‐functionalized biphenyl derivative in one dimension as a result of a rapid and efficient β‐cyclodextrin(CD)‐accelerated, cucurbit[6]uril(CB)‐templated azide–alkyne cycloaddition, while 2) the aromatic core of the dication is able to dimerize in a criss‐cross fashion by dint of π–π interactions, enabling simultaneous supramolecular assembly, resulting in an extended polymer network in an orthogonal dimension.