Nickel-Catalyzed Decarbonylative Alkynylation of Acyl Fluorides with Terminal Alkynes under Copper-Free Conditions

Nickel-catalyzed decarbonylative alkynylation of acyl fluorides with terminal silylethynes under copper-free conditions is described. This newly developed method has a wide substrate scope, affording internal silylethynes in moderate to high yields. The formation of 1,3-diynes as homocoupled products and conjugate enones as carbonyl-retentive products were effectively suppressed

Palladium-Catalyzed Decarbonylative Alkylation of Acyl Fluorides

Palladium-catalyzed decarbonylative alkylation reactions of acyl fluorides have been developed using alkylboranes having β-hydrogens. A wide range of functional groups were well tolerated, even at the high temperature required for decarbonylation. This protocol provides a diverse C(sp2)–C(sp3) bond formation via a highly efficient decarbonylative process. The hemilabile bidentate ligand DPPE plays a crucial role for retardation of the undesired β-hydride elimination

Synthesis and Physicochemical Properties of 2,7-Disubstituted Phenanthro[2,1-b:7,8-b']dithiophenes

We report the design, synthesis, and physicochemical properties of an array of phenanthro[2,1-b:7,8-b']dithiophene (PDT-2) derivatives by introducing five types of alkyl (CnH2n+1; n = 8, 10, 12, 13, and 14) or two types of decylthienyl groups at 2,7-positions of the PDT-2 core. Systematic investigation revealed that the alkyl length and the type of side chains have a great effect on the physicochemical properties. For alkylated PDT-2, the solubility was gradually decreased as the chain length was increased. For instance, C-8-PDT-2 exhibited the highest solubility (5.0 g/L) in chloroform. Additionally, substitution with 5-decylthienyl groups showed poor solubility in both chloroform and toluene, whereas PDT-2 with 4-decylthienyl groups resulted in higher solubility. Furthermore, UV-vis absorption of PDT-2 derivatives substituted by decylthienyl groups showed a redshift, indicating the extension of their pi-conjugation length. This work reveals that modification of the conjugated core by alkyl or decylthienyl side chains may be an efficient strategy by which to change the physicochemical properties, which might lead to the development of high-performance organic semiconductors

Synthesis of Dinaphtho[2,3-d:2',3'-d']anthra[1,2-b:5,6-b']dithiophene (DNADT) Derivatives: Effect of Alkyl Chains on Transistor Properties

To investigate organic field-effect transistor (OFET) properties, a new thienoacene-type molecule, 4,14-dihexyldinaphtho[2,3-d:2',3'-d']anthra[1,2-b:5,6-b']dithiophene (C6-DNADT), consisting of pi-conjugated nine aromatic rings and two hexyl chains along the longitudinal molecular axis has been successfully synthesized by sequential reactions, including Negishi coupling, epoxidation, and cycloaromatization. The fabricated OFET using thin films of C6-DNADT exhibited p-channel FET properties with field-effect mobilities (mu) of up to 2.6 x 10(-2) cm(2) V-1 s(-1), which is ca. three times lower than that of the parent DNADT molecule (8.5 x 10(-2) cm(2) V-1 s(-1)). Although this result implies that the installation of relatively short alkyl chains into the DNADT core is not suitable for transistor application, the origins for the FET performance obtained in this work is fully discussed, based on theoretical calculations and solid-state structure of C6-DNADT by grazing incidence wide-angle X-ray scattering (GIWAXS) and atomic force microscopy (AFM) analyses. The results obtained in this study disclose the effect of alkyl chains introduced onto the molecule on transistor characteristics

A Small Tokamak “NOVA II”

A small tokamak, NOVA II, has been designed and constructed. The major radius is 30 cm, the minor radius 6 cm and the maximum toroidal field 15 kG. The device has a removable shell assembly for studying the stabilizing effect of a conductive shell. The basic concept of design and the specifications of the principal components are described. In preliminary experiments, stable discharge was maintained for 15 msec or longer. The electron temperatures measured by diamagnetism and conductivity are both above 100 eV. An electron density of 1-2×10¹³ cm⁻³ was observed by a 6 mm microwave interferometer. Spectroscopy of impurity lines and intensity measurement of hard X-ray radiation are also described

Copper-Catalyzed Regioselective Aminothiolation of Aromatic and Aliphatic Alkenes with N-Fluorobenzenesulfonimide and Thiols through Three-Component Radical Coupling

Copper-catalyzed regioselective aminothiolation of terminal and internal alkenes with N-fluorobenzenesulfonimide and thiols has been developed. The three-component reaction is promoted by the addition of dimethyl sulfide. In addition to aromatic alkenes, aliphatic alkenes are subjected to the reaction, affording various aminothiolation adducts as single regioisomers. The radical process is proposed by preliminary mechanistic studies, involving radical trap and radical clock experiments

Synthesis of Benzoisoselenazolone Derivatives by Nickel-Catalyzed Dehydrogenative Direct Selenation of C(sp2)-H Bonds with Elemental Selenium in Air

Nickel-catalyzed direct selenation of benzamides bearing an 8-quinolyl auxiliary with elemental selenium provides benzoisoselenazolones in good yield via carbon-selenium and nitrogen-selenium bond formation under aerobic conditions. In addition to aryl C-H bonds, the method can also be applied to alkenyl C-H bonds, constructing an isoselenazolone skeleton. Simple mechanistic analysis shows that the reaction proceeds through a rate-determining C-H bond cleavage. The obtained benzoisoselenazolones are transformed into various organoselenium compounds and utilized as the catalyst for bromolactonization of alkenoic acids

A Shell-less Tokamak “NOVA”

A description is given of the experimental shell-less Tokamak NOVA. This apparatus is designed to investigate the stabilization of plasmas in a shell-less Tokamak device, first by the programand the feedback-control of the vertical magnetic field, and then by controlling the radial distribution of the longitudinal plasma current, The basic concepts of design and the constructional data of the principal components are shown, together with some results of preliminary experiments

Copper-catalyzed Regioselective Chloroamination of Alkenes with Chlorotrimethylsilane and N-Fluorobenzenesulfonimide under Microwave-assisted Conditions

A copper-catalyzed chloroamination of alkenes with chlorotrimethylsilane and N-fluorobenzenesulfonimide has been developed. The reactions were complete within 1 h at 120 degrees C by means of microwave heating. The present chloroamination proceeds with a perfect regioselectivity and is compatible with various functional groups. The preliminary mechanistic investigation revealed that the reaction involves a radical process. The utility of the present method was demonstrated by scalable, operationally simple and safe system