Acyloin condensation in aqueous system by durable polymer-supported thiazolium salt catalysts

We characterized three low-molecular-weight thiazolium salt analogues: N-methyl-5-(2′-benzyloxyethyl)-4-methylthiazolium iodide (MBMTI), N-methyl-4-phenylthiazolium iodide (MPTI), and N-methylbenzothiazolium iodide (MBTI). MBMTI, having high-electron density on the thiezolium ring, was found to be a durable thiazolium salt in buffer solution. Then, the polymer-supported thiazolium salt catalyst having MBMTI structure as a catalytic site for acyloin condensation was prepared by the polymerization of the corresponding thiazole monomer and the following quaternization. The polymer catalyst had excellent catalytic activity even in buffer solution, while the corresponding low molecular weight catalyst did not show any activity in aqueous system. Furthermore, the durable polymer catalyst could be reused under the aqueous condition. © 1994 John Wiley & Sons, Inc.     

Regioselective germylcupration of acetylenes

The reaction of terminal acetylenes with (Ph₃Ge)₂Cu(CN)Li₂ (1) or (Et₃Ge)₂Cu(SMe₂)Li (2) provides vinylgermanes in good yields. Whereas germylcupration of 1-dodecyne gives 2-germyl-1-dodecene as a main product, germylmetalation of phenylacetylene or 3-methyl-3-buten-1-yne affords 1-germyl compounds preferentially.     

Reaction of alpha,alpha-dibromo oxime ethers with Grignard reagents: alkylative annulation providing a pyrimidine core

A convergent synthesis of a pyrimidine core has been achieved. Treatment of alpha,alpha-dibromo oxime ethers, which are easily derived from the corresponding esters, with a variety of Grignard reagents provides trisubstituted pyrimidines in good yields. This new method offers an easy access to functionalized pyrimidines.     

Application of ion-pair high performance liquid chromatography for analysis of hyoscyamine and scopolamine in solanaceous crude drugs

A new ion-pair high-performance liquid chromatographic method for the analysis of hyoscyamine and scopolamine in various kinds of crude drugs derived from solanaceous plants was evaluated using sodium dodecyl sulfate as a counter ion. A reversed-phase chromatographic system consisting of a chemically bonded ODS silica gel column with phosphate buffer (pH 2.5)-acetonitrile (65:35) containing 17.5 mM sodium dodecyl sulfate as the mobile phase was used. Hyoscyamine and scopolamine in crude drugs derived from Scopolia, Atropa, Hyoscyamus and Datura species were separated from other compounds in the crude drugs and determined within 20 min after direct injection of the solution extracted with the mobile phase. The results for various kinds of samples are presented.     

Kinetic evidence for remote pi-aryl participation in the BF3-catalyzed rearrangement of [2 + 2] photocycloadducts of diarylhomobenzoquinones with diphenylacetylene

[reaction: see text] The BF(3)-catalyzed rearrangement of cyclobutene-fused m- and p-substituted diarylhomobenzoquinones exclusively gave the keto-alcohols via a Wagner-Meerwein vinyl-anion migration followed by the annulation of a delta-located endo-aryl group. The Hammett treatments for the endo/exo substituent effects, as well as the kinetic solvent effects, indicated that this reaction proceeds through the concerted S(N)2-like mechanism involving a rate-determining endo-aryl-assisted transition state.     

[2,6‐Bis(5‐methyl‐2‐pyridyl)phenyl‐κ3N,C1,N′]chloridoplatinum(II)

In the title compound, [Pt(C₁₈H₁₅N₂)Cl], the Pt^II centre adopts a distorted square‐planar coordination geometry due to the pincer‐type monoanionic N–C–N tridentate ligand. The planar complexes stack viaπ–π interactions to form two‐dimensional accumulated sheets. This packing pattern is in contrast to that in related pincer‐type N–C–N complexes, which exhibit a one‐dimensional columnar stacking.     

Synthesis and characterization of β-forming poly[S-(ω-N-carbazolylalkyl)-L-cysteine]s

Poly(L -cysteine derivative)s containing carbazole groups in the side chains separated from the backbone by several distances have been synthesized. It is revealed by measuring the IR spectra that they assume the antiparallel-chain pleated sheet (β-conformation) in the solid films independent of side chain length. DSC thermograms, and CD and fluorescence spectra of the films of these polymers are also presented in relation to the alignment of side-chain carbazole groups.     

Cyclopolycondensation. XIII. New synthetic route to fully aromatic poly(heterocyclic imides) with alternating repeating units

Fully aromatic poly(heterocyclic imides) of high molecular weight were prepared by the cyclopolycondensation reactions of aromatic diamines with new monomer adducts prepared by condensing orthodisubstituted aromatic diamines with chloroformyl phthalic anhydrides. The low-temperature solution polymerization techniques yielded tractable poly(amic acid), which was converted to poly(heterocyclic imides) by heat treatment to effect cyclodehydration at 250–400°C under reduced pressure. In this way, the polyaromatic imideheterocycles such as poly(benzoxazinone imides), poly(benzoxazole imides), poly(benzimidazole imides) and poly(benzothiazole imides) were prepared, which have excellent processability and thermal stability both in nitrogen and in air. The poly(amic acids) are soluble in such organic polar solvents as N,N-dimethyl-acetamide, N-methylpyrrolidone, and dimethyl sulfoxide, and the films can be cast from the polymer solution of poly(amic acids) (η_inh = 0.8–1.8). The film is made tough by being heated in nitrogen or under reduced pressure to effect cyclodehydration at 300–400°C. The polymerization was carried out by first isolating the monomer adducts, followed by polymerization with aromatic diamines. On subsequently being heated, the open-chain precursor, poly(amic acid), undergoes cyclodehydration along the polymer chain, giving the thermally stable ordered copolymers of the corresponding heterocyclic imide structure.     

Multiple prompt gamma-ray analysis and construction of its beam line

By combining neutron activation analysis with multiple gamma-ray detection (gamma-gamma coincidence), we have proved better sensitivity and resolution for the trace element analysis than the ordinary single gamma-ray detection method. We now try to apply the multiple gamma-ray detection method to the prompt gamma ray analysis (PGA). We have established a new cold neutron beam line for PGA in Japan Research Reactor, JRR-3M, at Tokai establishment of Japan Atomic Energy Research Institute (JAERI). It consists of a beam shutter, a beam attenuator, a gamma-ray detector array, a sample changer, and a beam stopper. We construct a high-efficiency gamma-ray detector array specially designed for this purpose. Its performance has been evaluated with the Monte Carlo simulation code, GEANT 4.5.0.