A remarkable solvent effect toward the Pd/C-catalyzed cleavage of silyl ethers

Selective hydrogenation conditions of olefin, benzyl ether and acetylene functionalities in the presence of TBDMS or TES ether have been developed.     

Molecular scale imaging of F-actin assemblies immobilized on a photopolymer surface

A photo-immobilization based process is presented for direct imaging of hierarchical assemblies of biopolymers using atomic force microscopy (AFM). The technique was used to investigate the phase behavior of F-actin aggregates as a function of concentration of the divalent cation Mg2+. The data provided direct experimental evidence of a coil-on-coil (braided) structure of F-actin bundles formed at high Mg2+ concentrations. At intermediate Mg2+ concentrations, the data showed the first images of the two-dimensional nematic rafts discovered by recent x-ray studies and theoretical treatments.     

Development of diversified methods for chemical modification of the 5,6-double bond of uracil derivatives depending on active methylene compounds

The reaction of 5-halogenouracil and uridine derivatives 1 and 7 with active methylene compounds under basic conditions produced diverse and selective C-C bond formation products by virtue of the nature of the carbanions. Three different types of reactions such as the regioselective C-C bond formation at the 5- and 6-positions of uracil and uridine derivatives (products 2, 5, 8, 17, 20 and 21), and the formation of fused heterocycle derivatives 2,4-diazabicyclo[4.1.0]heptane (15) and 2,4-diazabicyclo-[4.1.0]nonane (16) via dual C-C bond formations at both the 5- and 6-positions were due to the different active methylene compounds used as reagents.     

Pd-catalyzed amidation of aryl chlorides using monodentate biaryl phosphine ligands: a kinetic, computational, and synthetic investigation

We present results on the amidation of aryl halides and sulfonates utilizing a monodentate biaryl phosphine-Pd catalyst. Our results are in accord with a previous report that suggests that the formation of kappa(2)-amidate complexes is deleterious to the effectiveness of a catalyst for this transformation and that their formation can be prevented by the use of appropriate bidentate ligands. We now provide data that suggest that the use of certain monodentate ligands can also prevent the formation of the kappa(2)-amidate complexes and thereby generate more stable catalysts for the amination of aryl chlorides. Furthermore, computational studies shed light on the importance of the key feature(s) of the biaryl phosphines (a methyl group ortho to the phosphorus center) that enable the coupling to occur. The use of ligands that possess a methyl group ortho to the phosphorus center allows a variety of aryl and heteroaryl chlorides with various amides to be coupled in high yield.     

Starburst-Type Carbazole Trimers as Host Materials for Solution-Processed Phosphorescent OLEDs

Novel starburst-type carbazole trimers SB-1 and SB-2 were developed as hole-transporting host materials for phosphorescent organic light-emitting diodes (PhOLEDs). The triplet levels (T₁s) of SB-1 and SB-2 were determined as at 2.81 and 2.73 eV, respectively. Also, these compounds afforded stable amorphous thin films upon spin-coating, and thus it was found that they are applicable to solution-processed devices. Indeed, blue PhOLEDs were fabricated by a solution method using SB-1 and SB-2 as host materials, where better device performance was obtained for the SB-1-based device due to its higher-lying T₁.     

Concise Synthesis of Multisubstituted Isoquinolines from Pyridines by Regioselective Diels–Alder Reactions of 2‐Silyl‐3,4‐pyridynes

A four‐step regioselective synthesis of multisubstituted isoquinoline derivatives from 3‐bromopyridines was developed by the Diels–Alder (DA) reactions of 2‐silyl‐3,4‐pyridynes with furans, followed by functional‐group transformations. In particular, the silyl group at the C2‐position of the 3,4‐pyridynes played two important roles: firstly, it functioned as the directing group for the DA reaction, and secondly, it served to introduce diverse substituents at the C1‐position of the isoquinolines by electrophilic ipso‐substitution.     

1,3-O- to -C-alkyl migration of 1-alkenyl alkyl acetals and ketals catalyzed by boron trifluoride. Selective cross- and regioselective aldol type reactions

1,3-Alkyl migration of 1-alkenyl alkyl acetals and ketals is effectively catalyzed by trifluoroborane etherate to give cross aldol type products selectively. Remarkable regio-selectivity is observed in the synthesis of α-alkyl-β-alkoxy-ketones.     

Measurement of far-infrared optical constants by ATR

Using an optically-pumped far-infrared laser as a light source, the far-infrared optical constants of liquid acetonitrile, methanol, dichloromethane, and chlorobenzene were obtained by measuring the attenuated total reflections of light for two mutually perpendicular polarizations. The ATR prism of hyper-pure silicon was made asymmetric to avoid the effect of the multiple reflection inside the prism.