Miki Murata

Rhodium-catalyzed dehydrogenative coupling reaction of vinylarenes with pinacolborane to vinylboronates

Abstract The treatment of pinacolborane with vinylarenes in the presence of a catalytic amount of [RhCl(cod)] 2 , through a dehydrogenative borylation, provides pinacol esters of ( E )-2-arylethenylboronates.

Regio- and stereoselective synthesis of allylboranes via platinum(0)-catalyzed borylation of allyl halides with pinacolborane

Abstract Various allyl halides were borylated with pinacolboranes in the presence of NEt 3 and a catalytic amount of Pt(dba) 2 and AsPh 3 to afford regio- and stereodefined allylboranes in good yields.

Synthesis of alkenylsilanes via palladium(0)-catalyzed silylation of alkenyl iodides with hydrosilane

Abstract Various alkenyl iodides were silylated with hydrosilanes in the presence of KOAc and a catalytic amount of Pd 2 (dba) 3 ·CHCl 3 to afford the corresponding regio- and stereodefined ( E )-alkenylsilanes in high yields.

Preparation of core-shell polystyrene-polyimide particles by dispersion polymerization of styrene using poly(amic acid) as a stabilizer

Dispersion polymerization of styrene (S) and vinylbenzyltrimethylammonium chloride (VBA) was conducted in an ethanol-water medium using an aromatic poly(amic acid) (PAA) as the stabilizer. When equimolar amounts of VBA and the carboxylic acid of PAA were used, monodisperse particles with high PAA content were obtained quantitatively. The imidization of PAA on the particles proceeded with acetic anhydride and N,N-dimethylaminopyridine to form core-shell PS-polyimide particles.

SYNTHESIS OF BENZYLBORONATES VIA PALLADIUM-CATALYZED BORYLATION OF BENZYL HALIDES WITH PINACOLBORANE

ABSTRACT Various benzyl halides were borylated with pinacolborane in the presence of i Pr2NEt and a catalytic amount of PdCl2(PPh3)2 to afford the corresponding benzylboronates in good yields.

PALLADIUM- OR NICKEL-CATALYZED COUPLING REACTION OF DIALKOXYBORANES WITH CHLOROARENES: ARYLATION OF 1,3,2-DIOXABOROLANES OR 1,3,2-DIOXABORINANES

The borylation of electron-deficient aryl chlorides with pinacolborane proceeded in the presence of Bu 4 NI and a catalytic amount of Pd(dba) 2 / bis(2-di-tert-butylphosphinophenyl) ether. The combination of NiCl 2 (dppp) catalyst and Bu 4 NBr was also efficient for the borylation of aryl chlorides.

Site-Selective Aliphatic C−H Silylation of 2-Alkyloxazolines Catalyzed by Ruthenium Complexes

The Ru‐catalyzed dehydrogenative silylation of 2‐alkyloxazolines with 1,1,1,3,5,5,5‐heptamethyltrisiloxane took place site‐selectively at methyl C(sp3)−H bonds located γ to the nitrogen atom of the oxazolyl groups. Pyridine and pyrazole rings could also be used as a directing group. A catalytic mechanism based upon successive σ‐bond metathesis is proposed.

Ruthenium‐Catalyzed Ortho‐Selective Aromatic CH Borylation of 2‐Arylpyridines with Pinacolborane

The ruthenium‐catalyzed dehydrogenative borylation of 2‐arylpyridines with pinacolborane took place at ortho‐positions of the benzene ring. Density functional theory calculations and kinetic isotope effect experiments suggest that the catalytic cycle should involve oxidative addition of the CH bond, the rate‐determining σ‐bond metathesis of pinacolborane with the ruthenium hydride complex, and reductive elimination of the CB bond.

Transition Metal-catalyzed Silylation of Organic Halides with Hydrosilanes

Since arylsilanes are versatile reagents for carbon-carbon bond formation, the supply of functionalized and reactive arylsilanes has become more necessary. We demonstrated the first example of the palladium(0)-catalyzed silylation of aryl halides with triethoxysilane as a silicon source and affording the corresponding aryltriethoxysilanes. Although this catalyst system has lacked the wide applicability to functionalized substrates, we found that a rhodium(I) complex overcomes a number of limitations of the palladium(0)-catalyzed silylation. The silylation of aryl iodides with hydrosilanes was able to apply to 1,1,1,3,5,5,5-heptamethyltrisiloxane by the appropriate choice of catalyst systems. 3-Aryl-1,1,1,3,5,5,5-heptamethyltrisiloxanes were also provided by platinum-catalyzed dehydrogenative coupling with aromatic hydrocarbons. These catalytic silylations supply a wide range of functionalized arylsiloxanes.

Synthesis and Characterization of Aromatic Polyimide Containing 3,6-Diamino-9-Alkylcarbazole and Aromatic Tetracarboxylic Dianhydrides

New soluble polyimides with inherent viscosities of 0.25–0.62 dl g−1 were synthesized from 3,6-diamino-9-alkylcarbazole and various aromatic tetracarboxylic dianhydrides by the conventional two-step method, including ring-opening polyaddition and subsequent thermally cyclodehydration. Most of the polyimides having hexyl alkyl chains were soluble in N-methylpyrrolidinone and m-cresol, while the polymers having ethyl chains were not soluble in organic solvents. The glass transition temperatures and 10% weight loss temperatures under argon of the polyimides having hexyl chains were in the ranges 232–269 °C and 485–518 °C, respectively.