Divinylbenzene derivatives represent an important class of molecular building blocks in organic chemistry and materials science. Reported herein is the palladium-catalyzed synthesis of divinylbenzenes by meta-C-H olefination of sulfone-based arenes. Successful sequential olefinations in a position-selective manner provided a novel route for the synthesis of hetero-dialkenylated products, which are difficult to access using conventional methods. Additionally, 1,3,5-trialkenylated compounds can be generated upon successful removal of the directing group.

Nano crystals of γ-Fe 2 O 3 (maghemite) were synthesized by emulsion precipitation method using kerosene as oil phase, SPAN-80 (sorbitane monooleate) as the surfactant and sodium hydroxide as the precipitating agent. The characterization of the samples by FTIR (Fourier transform infra-red) and XRD (X-ray diffraction) techniques confirmed the formation of γ-Fe 2 O 3 (maghemite). Analysis by SEM (scanning electron microscope) and TEM (transmission electron microscope) was carried out to study the morphology and particle size. The as prepared samples contained inverse spinel cubic phase maghemite. Effect of initial iron concentration on crystallite size of maghemite showed that it decreased with the decrease in initial iron concentration. Transformation of γ-Fe 2 O 3 to α-Fe 2 O 3 (hematite) was studied by calcining the precursor in the temperature range of 500 to 850°C. Formation/transformation of phases at different temperatures was confirmed by FTIR and XRD studies. Images, obtained by SEM and TEM showed the morphology and nanocrystal formation of hematite. Room temperature rheological behaviour of the synthesized α-Fe 2 O 3 nano powder has been studied.

Reagent Information. Unless otherwise stated, all reactions were carried out under air atmosphere in screw cap reaction tubes. All solvents were bought from Merck and TCI [1,1,1,3,3,; CAS: 920-66-1] in a sure-seal bottle and were used as received. Silver carbonate, all MPAA ligands were purchased from Alfa Aeser. Diethyl benzyl phosphonates for the synthesis of final starting materials were obtained from Aldrich and Alfa Aesar. Olefins were obtained from Alfa Aeser, Sigma Aldrich and Spectrochem. For column chromatography, silica gel (100-200 mesh) obtained from SRL Co. was used. A gradient elution using pet ether and ethyl acetate was performed, based on Merck aluminum TLC sheets (silica gel 60F 254 ).Analytical Information. All isolated compounds were characterized by 1 H, 13 C, and in few cases 1D-NOE, NOESY, HSQC NMR spectroscopy, IR spectroscopy, Gas chromatography mass spectra (GC-MS)/HR-MS for some compounds. Copies of NMR files can be found in the supporting information. Unless otherwise stated, all Nuclear Magnetic Resonance spectra were recorded on a Bruker 400 and 500 MHz instrument. 31 P-NMR spectra reported in the supporting information was recorded in Bruker 500 MHz instrument. The references used for the NMR are tetramethylsilane (TMS) for 1 H and 13 C-NMR. All 1 H-NMR experiments are reported in units, parts per million (ppm), and were measured relative to the signals for residual chloroform (7.26 ppm) in the deuterated solvent, unless otherwise stated. All 13 C-NMR spectra were reported in ppm relative to deuterochloroform (77.23 ppm), unless otherwise stated, and all were obtained with 1 H decoupling. Neat infrared spectra were recorded on a Perkin-Elmer spectrum one FT-IR spectrometer. The data was recorded in transmittance mode (%T, cm -1 ). The melting points were measured in Büchi Melting Point Model B-545 apparatus. All NMR analysis were performed 1,3,5-trimthoxybenzene as the internal standard. High-resolution mass spectra (HRMS) were recorded on a micro-mass ESI TOF (time of flight) mass spectrometer.

We have for the first time developed two ligand-assisted Cu(I)-catalyzed sequential intra- and intermolecular S-arylations leading to the direct synthesis of arylthiobenzothiazoles in one pot without an inert atmosphere. Low catalyst loading, inexpensive metal catalyst and ligand, lower reaction temperature, and shorter reaction times make this method superior to all reported methods for the synthesis of arylthiobenzothiazole.

2-Fluoro and 2-chloro aryl thioureas, which are usually inert toward heteroarylation forms intramolecular C−S linkage by Cu(I) and Pd(II) catalyst. A regioselective intramolecular C−S bond formation is observed during the formation of 2-aminobenzothiazoles from 2-halothioureas using both these transition metal catalysts. While Cu prefers a dehalogenative path, Pd favors predominantly C−H activation strategy during the formation of 2-aminobenzothiazoles. In the absence of 2-halo (−F, −Cl) groups, Pd favors C−H activation, while Cu is unproductive. However, identical selectivities were observed both for Cu-and Pd-catalyzed reactions for 2-bromo and 2-iodo aryl thioureas.

Decarboxylative coupling reactions to date require a stoichiometric oxidant (such as copper and silver salts) for decarboxylation purposes along with a metal catalyst (e.g. palladium) for cross-coupling. In this communication, an economic and sustainable approach by using a simple copper salt was developed in the presence of molecular oxygen as the sole oxidant. A wide range of 5-membered heteroarenes undergo aryl-heteroaryl cross-coupling with electron deficient aryl carboxylic acids.

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