Oxindole Synthesis by Direct Coupling of C?H and C?H Centers

An sp ² /sp ³ get‐together : A novel and efficient method can be used to synthesize 3,3‐disubstitued oxindoles by the direct intramolecular oxidative coupling of an aryl C? H and a C? H center (see scheme; DMF=N,N‐dimethylformamide).

     

Synthesis and properties of new Si?H-containing polymers

Poly[(methylsilylene)ethynylene] ( 1 ) and poly[2,5-thiophenediyl(methylsilylene)] ( 2 ) are prepared in good yields. Thermogravimetric analysis and differential scanning calorimetry indicate the Si H group to increase the pyrolysis residue yields. Gelation was achieved from polymer 1 to get improved preceramic materials. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2275–2282, 1998     

Synthesis of Dimethyl Tetraarylphthalates by Suzuki?Miyaura Reactions of Dimethyl Tetrabromophthalate

Tetraarylphthalates were prepared by Suzuki? Miyaura reactions of dimethyl tetrabromophthalate.     

Simple Sulfinate Synthesis Enables C?H Trifluoromethylcyclopropanation

A simple method to convert readily available carboxylic acids into sulfinate salts by employing an interrupted Barton decarboxylation reaction is reported. A medicinally oriented panel of ten new sulfinate reagents was created using this method, including a key trifluoromethylcyclopropanation reagent, TFCS‐Na. The reactivity of six of these salts towards C H functionalization was field‐tested using several different classes of heterocycles.     

Studies on the Synthesis and Characterization of Pd?TiO2?SiO2 Nanocomposite for Electroanalytical Applications

A nanocomposite of Pd? TiO₂? SiO₂ is developed through a sol‐gel process from the reaction products of titanium isopropoxide followed by mixing the same with palladium linked 3‐glycidoxypropyltrimethoxysilane. The reaction product is sonicated and calcinated to obtain the nanocomposite of Pd? TiO₂? SiO₂. The calcination at 600 °C yielded an amorphous structure whereas at 900 °C it resulted into a nanocrystalline structure. The nanocomposite of palladium was further characterized by TEM, XRD, IR and EDS. The material acts as an efficient electrocatalyst. Electrocatalysis of ascorbic acid is observed at 0.1 V vs. Ag/AgCl, shows linearity between 1 µM and 1 mM in 0.1 M phosphate buffer (pH 7.0).     

A theoretical investigation of Zn?Zn and Be?Be one electron bond

Attachment of one electron to 1,2-diBeX-benzene and 1,2-diZnX-benzene derivatives leads to the formation of stronger Be Be and Zn Zn interaction compared to the neutral one. This is reflected in the dramatic shortening of the Be Be and Zn Zn distance. The formation of these 2-center-1-electron bonds have also been confirmed by topological survey of electron density using quantum theory of atoms in molecules and electron localization function. The formation of these bonds is expected to render stability to these radical anions. These radical anions are stable toward electron detachment and computed bond dissociation energy values are also significant.     

Synthesis and properties of fluorinated benzotriazole-based donor-acceptor-type conjugated polymers via Pd-catalyzed direct C?H/C?H coupling polymerization

Fluorine substituted benzotriazole (BTz) units have shown great potential in improving various conjugated polymers (CPs)-based optoelectronic devices' performance. Thus, it is highly expected for the establishment of simple, efficient, and inexpensive accesses to such polymers. In this paper, Pd-catalyzed direct C H/C H coupling polymerization is first employed for the synthesis of 5,6-difluorobenzotriazole containing π-CPs, which fully avoids prefunctionalization of monomers. Under the optimized conditions, a series of donor-acceptor-type π-CPs with excellent regio-regularity are facilely obtained via the direct C H/C H coupling reaction of 5,6-difluoro-2-(2-hexyldecyl)-2H-BTz with different thiophene analogs. The chemical structure of the as-synthesized polymers are confirmed by NMR technique including ¹H NMR, ¹⁹F NMR, and the edited heteronuclear singular quantum correlation and heteronuclear multiple bond correlation spectra as well as comparative study on the same polymers obtained via Stille coupling and direct (hetero)arylation polymerization. Further, their optical properties, electrochemical properties, and thermal stabilities are also carefully explored by UV–Vis absorption spectra, cyclic voltammograms as well as thermogravimetric analysis, respectively. On the basis of density functional theory (DFT) simulation, the effect of alkyl substituents attached to thiophene units on the reactivity and optical performance of the resultant polymers is explained. Our protocol exhibits remarkable advantages in synthetic simplicity, atom-economy, high efficiency, and excellent regioselectivity of cross-coupling, providing an alternative synthetic strategy for high-performance optoelectronic materials.     

Cyclic S?N compounds and phosphorus reagents: Part X. Synthesis and characterization of phosphinimino-substituted S?N heterocycles

Room temperature reactions of S₄N₄ with (amino) diphenylphosphines, (R)Ph₂P, have basically yielded two different types of S N heterocycles under two different stoichiometric conditions. Phosphiniminocyclotrithiatriazenes, (R)Ph₂PN S₃N₃ (R = C₄H₈N , C₅H₁₀N , C₆H₁₂N , CH₃NC₄H₈N , (C₆H₁₁)₂ N , and (C₆H₅CH₂)₂N ) have been obtained (yield 45–76%) from a 1:2 mole ratio (S₄N₄:(R)Ph₂P) reaction, while the disubstituted S₄N₄ derivatives, 1,5-[Ph₂(R)PN]₂S₄N₄ (R = C₄N₈N , C₅H₁₀N , and C₆H₁₂N ) have been obtained (yield 30–45%) only from a 1:3.5–4 mole ratio reaction. All the 1,5-[Ph₂(R)PN]₂S₄N₄ derivatives prepared in this study undergo a room temperature solution phase transformation to the corresponding (R)Ph₂PN S₃N₃ heterocycles.     

Intramolecular H?Ar Ligand Exchange between Silicon and Boron: Functionality Transfer of Si?H to B?H

o‐C₆H₄(SiR_3?nH_n)(BMes₂) ( 1 ; R=Me, Ph; n=1, 2) undergo Mes? H (Mes=mesityl) ligand exchange between the silicon atom and the boron atom to form o‐C₆H₄(SiMesR_3?nH_n?1)(BMesH) ( 6 ) upon heating. The resulting hydroborane intermediates ( 6 ) immediately react with benzaldehyde to afford their corresponding benzyloxyboranes ( 5 ). A DFT study of model compounds reveals the transition states of the ligand exchange. A hydride abstraction from the silicon atom by the boron center is key to reaching the transition states, which include the tricoordinate silyl‐cation moiety and the tetracoordinate hydridoborate moiety.     

B?H,C?H,and B?C Bond Activation: The Role of Two Adjacent Agostic Interactions

Tuning the nature of the linker in a L∼BHR phosphinoborane compound led to the isolation of a ruthenium complex stabilized by two adjacent, δ‐C H and ε‐B_sp2 H, agostic interactions. Such a unique coordination mode stabilizes a 14‐electron “RuH₂P₂” fragment through connected σ‐bonds of different polarity, and affords selective B H, C H, and B C bond activation as illustrated by reactivity studies with H₂ and boranes.     

Synthesis of Allyl Aryl Sulfone Derivatives from Baylis?Hillman Acetates in Water

Various phenyl and p‐tolyl allyl sulfone derivatives were prepared stereoselectively by reacting Baylis? Hillman acetates with sodium 4‐R‐benzenesulfinate (R=H, Me) in H₂O. The reaction was very efficient in providing the corresponding sulfone derivatives in good to excellent yields (Table).