Amino acids and peptides. LIV. Application of 2-adamantyl derivatives as protecting groups to the synthesis of peptide fragments related to Sulfolobus solifataricus ribonuclease. I.

The 2-adamantyloxycarbonyl group was employed for the protection of the epsilon-amino group of Lys and the hydroxyl group of Tyr, and the 2-adamantyl ester was employed for the protection of the beta-carboxyl group of Asp in order to construct eight peptide segments as building blocks for the preparation of peptide fragments related to the sequence of Sulfolobus solifataricus Ribonuclease. The usefulness of the above protecting groups developed in our laboratory was confirmed.     

An improved synthesis of butyl 4-[(4-amino-5-chloro-2-methoxybenzoyl)amino]-1-piperidineacetate (AU-224).

A new and facile route for the synthesis of the novel gastrointestinal prokinetic butyl 4-[(4-amino-5-chloro-2-methoxybenzoyl)amino]-1-piperidineacetate (1b), which exhibited potent gastro- and colon-prokinetic activities by oral administration without significant side effects, was established. The key intermediate, butyl 4-amino-1-piperidineacetate (16), was prepared from commercially available 4-amino-1-benzylpiperidine (2) in a high yield with four steps. Compound 1b was prepared by condensation of commercially available 4-amino-5-choloro-2-methoxybenzoic acid (7) with 16 in 84% yield. This improved synthetic route was appropriate for large-scale synthesis of 1b.     

Synthesis of a polyester macromonomer via the cobalt-catalyzed alternating copolymerization of propylene oxide and carbon monoxide

The alternating copolymerization of propylene oxide and carbon monoxide was investigated with cobalt complexes. The NaCo(CO)₄/amine catalyst system selectively yielded oligo(3-hydroxybutyrate)s bearing a polymerizable crotonate end group, whereas the use of Co₂(CO)₈ as a cobalt source resulted in a smaller concentration of the crotonate end group and a high degree of polymerization. The high selectivity for the oligoesters with the crotonate end group with the NaCo(CO)₄/amine system was attributed to its more basic reaction condition. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4666–4670, 2004     

Strong-symmetry-breaking limit of SU(3) Skyrme model and bound-kaon approach to strangeness

The semi-leptonic weak decays of hyperons are investigated in the Skyrme model. The vector currents for strangeness-changing processes are shown to have a very similar structure in the strong-symmetry-breaking limit in the SU(3) collective-coordinate method, proposed by Yabu and Ando, with those in the bound-kaon approach to strangeness by Callan and Klebanov. It is also shown that the quite differentN _c dependence between them becomes also to coincide with each other in the limit.Dedicated to Prof. Erich Schmid on the occasion of his 60th birthday     

Ladder type supramolecular assembly and gas adsorption profile under reduced pressure based on hydrogen bonded m-tetraphenyl derivative of anthracene

We report a guest adduct X-ray structures and gas adsorption capability of 9,10-bis(4″,4-dihydroxyl-m-terphen-5″-yl)anthracene, which is an analogue of anthracene-bis(resorcinol) derivative reported by Aoyama et al. The gas adsorption capability is double scale of guest inclusion than that of anthracene-bis(resorcinol) derivative.     

Deposition of microcrystalline silicon films at ultrafast rate by using a new microwave induced plasma source

Synthesis of microcrystalline silicon (μc-Si) film at an ultrafast deposition rate over 100 nm/s is achieved from SiH₄ + He by using a high density microwave plasma source even without employing H₂ dilution and substrate heating techniques. Systematic deposition studies show that high SiH₄ flow rate and working pressure increase film deposition rate while high He flow rate decreases the rate. On the other hand, crystallinity of deposited Si film decreases with increasing SiH₄ or He flow rate and working pressure. Enhancements of gas phase and surface reactions during film deposition process are responsible for the achievement of high deposition rate and high film crystallinity.     

Electron spin resonance study of hydrogenated microcrystalline silicon–germanium alloy thin films

Paramagnetic defects of undoped hydrogenated microcrystalline silicon–germanium alloys (μc-Si_1?xGe_x:H) grown by low temperature (200 °C) plasma-enhanced chemical vapor desposition (PECVD) have been measured by electron spin resonance (ESR) and compared with those of hydrogenated amorphous silicon–germanium (a-Si_1?xGe_x:H). The spin density of μc-Si_1?xGe_x:H increases with Ge content and shows a broad maximum of ～10¹⁷ cm^?3 at x ～ 0.5, which reasonably accounts for the decreased photoconductivity. While the Ge dangling bond defects prevail in a-Si_1?xGe_x:H for Ge-rich compositions, we detected no ESR signal in μc-Si_1?xGe_x:H for x > 0.75 where an electrical change occurs from weak n- to strong p-type conduction. These results indicate that dangling bonds are charged in large densities due to the presence of the acceptor-like states in undoped μc-Si_1?xGe_x:H.     

Funktionelle Monomere und Polymere. 37. Mitt. Zur Synthese und Polymerisation von Styrolderivaten,die Adenin und Cytosin enthalten

Ohne Zusammenfassung     

An improved procedure for the synthesis of 1,1-difluoro-2-hydroxyalkylphosphonates

The reaction of diethyl difluoro(trimethylsilyl)methylphosphonate with arenecarbaldehydes and aryl methyl ketones is effected with the aid of a catalyst. cesium fluoride, at room temperature to afford the title compounds.