Practical and robust method for regio- and stereoselective preparation of (E)-ketene tert-butyl TMS acetals and beta-ketoester-derived tert-butyl (1Z,3E)-1,3-bis(TMS)dienol ethers

We developed an efficient, practical, robust method for the regio- and stereoselective preparation of (E)-ketene trimethylsilyl acetals (KSAs) derived from tert-butyl esters 1. The reaction was performed under convenient reaction conditions; LDA-TMSCl, 0-5 degrees C, and cyclopentyl methyl ether (CPME) solvent. Two kinds of (Z)- and (E)-KSAs derived from alpha-oxygen and alpha-nitrogen-substituted tert-butyl esters, respectively, were also obtained in good yield. The present protocol was successfully applied to a stereocontrolled preparation of useful, but highly reactive (less accessible) beta-ketoester-derived tert-butyl (1Z,3E)-1,3-bis(TMS)dienol ethers 2.     

Development of chlorotriazine polymer dehydrocondensing reagents (Poly-Trzs)

Polymer-type dehydrocondensing reagents comprising of a triazine dehydrocondensing reagent, itself in a polymerized form (Poly-Trz—MMs'), have been developed by exploiting the chemical properties of cyanuric chloride that readily binds to alcohol or amines. A chlorotriazine polymer bearing two alkoxy substituents at the 4- and 6- positions (Poly-O-Trz-Cl) was prepared by alternating copolymerization between cyanuric chloride and tetra(ethylene glycol). Similarly, polymers bearing both alkoxy and amino substituents (Poly-N-Trz-Cl) were synthesized from tetra(ethylene glycol) bis(4,6-dichlorotriazin-2-yl) ether 6 and tris(2-aminoethyl)amine 7 and/or ethylenediamine 8. All the polymers were shown to be good reagents for dehydrocondensation of carboxylic acids and amines in the presence of NMM, compared to the corresponding monomeric dehydrocondensing reagent (DMT-MM). The advantages of the polymeric reagents are as follows: (1) both the reaction and isolation procedure of dehydrocondensation can be greatly simplified, (2) the dehydrocondensation can be conducted in protic solvents as well as in common organic solvents, (3) the reagents can be efficiently prepared at a low cost, and (4) these reagents are considered eco-friendly, generating a lower amount of waste compared to conventionally related reagents because of high loading of the dehydrocondensing activity (ca. 3 mequiv/g).     

Syntheses,Structures, and Reactivities of Two Chalcogen‐Stabilized Carbones

Electronic effects on the central carbon atom of carbone, generated by the replacement of the S^IV ligand of carbodisulfane (CDS) with other chalcogen ligands (Ph₂E, E=S or Se), were investigated. The carbones Ph₂E→C←SPh₂(NMe) [E=S( 1 ) or Se( 2 )] were synthesized from the corresponding salts, and their molecular structures and electronic properties were characterized. The carbone 2 is the first carbone containing selenium as the coordinated atom. DFT calculations revealed the electronic structures of 1 and 2 , which have two lone pairs of electrons at the carbon center. The trend in HOMO energy levels, estimated by cyclic voltammetry measurements, for the carbones and CDS follows the order of 2 > 1 >CDS. Analysis of a doubly protonated dication and trication complex revealed that the central carbon atom of 2 behaves as a four‐electron donor.     

Ga‐focused ion beam time‐of‐flight secondary ion mass spectrometer analysis of the grain boundary segregation/precipitation of boron in steel

Ga‐focused ion beam time‐of‐flight secondary ion mass spectrometry (FIB‐TOF‐SIMS) analysis was performed to investigate the grain boundary segregation/precipitation of boron in steel. To overcome the low secondary ion yield from the primary Ga⁺ source and the sensitivity using a high‐resolution Ga‐FIB source, a low energy oxygen ion beam was used prior to the Ga‐FIB‐TOF‐SIMS analysis. As a result, it was found that Ga‐FIB‐TOF‐SIMS is a very powerful tool for mapping boron segregation and/or precipitation in steel with a spatial resolution of ~200 nm. In addition, the results were strongly dependent on the surface composition. Copyright © 2014 John Wiley & Sons, Ltd.     

Improved Synthesis and Reaction of 11‐Chloroneocryptolepines,Strategic Scaffold for Antimalaria Agent,and Their 6‐Methyl Congener from Indole‐3‐carboxylate

Various 11‐chloro‐5‐methyl‐5H‐indolo[2,3‐b]quinolines (neocryptolepines) with different substituents on the quinoline ring, key intermediates for antimalaria agents, are prepared from the substituted N‐methylanilines, easily accessible by the N‐methylation of anilines, and indole‐3‐carboxylate as a counterpart. This protocol is benign in terms of the reduced number of steps to reach the target, compared with the known method using anilines, and easy product purification. Alternatively, their 6‐methyl congener is prepared by N‐methylation of the indole moiety of 2‐arylaminoindole‐3‐carboxylate followed by successive cyclization and chlorination. 11‐Chloroneocryptolepines are found more reactive than their 6‐methyl congener in the nucleophilic substitution at the C11 position.     

Wet deposition of titania-apatite composite in cotton fibrils

Titania consisting of rutile and anatase was precipitated on and inside of cotton fibrils when cotton was soaked in an aqueous solution of 30 mM TiOSO₄ and 30 mM H₂O₂ kept at 80°C for 24 h. As the resultant titania-cotton fibrils were soaked in a simulated body fluid (Kokubo solution), apatite was deposited on the fibrils to yield cotton-titania-apatite composites within 1 d. Thus, the present study provided a simple technique to prepare titania-apatite composites and coatings on organic materials at low temperature. Presented at the Sol-gel 2005 in Los Angeles     

Low‐CTE photosensitive polyimide based on semialicyclic poly(amic acid) and photobase generator

A negative‐type photosensitive polyimide (PSPI) based on semialicyclic poly(amic acid) (PAA), poly(trans‐1,4‐cyclohexylenediphenylene amic acid), and {[(4,5‐dimethoxy‐2‐nitrobenzyl)oxy]carbonyl} 2,6‐dimethylpiperidine (DNCDP) as a photobase generator has been developed as a next‐generation buffer coat material. The semialicyclic PAA was synthesized from 3,3′,4,4′‐biphenyltetracarboxylic dianhydride and trans‐1,4‐cyclohexyldiamine in the presence of acetic acid, and the PAA polymerization solution was directly used for PSPI formulation. This PSPI, consisting of PAA (80 wt %) and DNCDP (20 wt %), showed high sensitivity of 70 mJ/cm² and high contrast of 10.3, when it was exposed to a 365‐nm line (i‐line), postexposure baked at 190 °C for 5 min, and developed with 2.38 wt % tetramethylammonium hydroxide aqueous solution containing 20 wt % isopropanol at 25 °C. A clear negative image of 6‐μm line and space pattern was printed on a film, which was exposed to 500 mJ/cm² of i‐line by a contact printing mode and fully converted to poly(trans‐1,4‐cyclohexylenebiphenylene imide) pattern upon heating at 250 °C for 1 h. The PSPI film had a low coefficient of thermal expansion of 16 ppm/K compared to typical PIs, such as prepared from 3,3′,4,4′‐biphenyltetracarboxylic dianhydride and 4,4′‐oxydianiline. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1317–1323, 2010     

Adoption of a genetic algorithm (GA) for tomographic reconstruction of line-of-sight optical images

 A new tomographic reconstruction scheme is proposed that uses a genetic algorithm (GA), a robust and combinatorial function optimization based on the mechanics of the genetic principle. The paper first discusses the implicitly parallel and scaled random nature of the GA optimization using an illustrative example. An introduction of the elementary distribution function (EDF) to constitute the cross-sectional field shows a successful adoption of GA for optical tomography. The GA-based tomography was examined for interferometric projections of computer-synthesized phantom density fields. The GA-based tomography shows accurate and stable image reconstruction, particularly for limited projections. Received: 6 November 1995 / Accepted: 6 May 1996     

Study of theω π + system

The mass spectra of theω π ⁰ system, produced inπ ^? p charge-exchange reactions at 38 GeV/c and 100 GeV/c, show a new neutral state with a mass of 2200±20 MeV and a width of 260±50 MeV. Likeρ ₃(1690), this meson,X(2200), is produced through one-pion-exchange.X(2200)J ^PC is likely 1^??. It might be a 2³ D ₁ radial-orbital excitation ofρ ⁰. Its production cross section falls with energy quadratically, in agreement with one-pion-exchange. The cross sections forb ₁(1235) andρ ₃(1690) production have also been measured; their energy dependences have been determined.     

Asymmetric α-2-tosylethenylation of N,N-dialkyl-L-amino acid esters via the formation of non-racemic ammonium enolates

Asymmetric α-2-tosylethenylation of (S)-2-(pyrrolidin-1-yl)propanoic acid esters was shown to produce good yields with high enantioselectivities. The reaction proceeds via the formation of a non-racemic ammonium enolate without an external source of chirality.