Synthesis of novel chiral bisazetidines by the hydroalane reduction of bis-beta-lactams

A series of novel chiral bisazetidines in which two azetidine rings are either directly connected or coupled in tandem style, are synthesized in good yields by the hydroalane reduction of the corresponding bis-beta-lactame.     

Expanding direction of the period doubling operator

We prove that the period doubling operator has an expanding direction at the fixed point. We use the induced operator, a Perron-Frobenius type operator, to study the linearization of the period doubling operator at its fixed point. We then use a sequence of linear operators with finite ranks to study this induced operator. The proof is constructive. One can calculate the expanding direction and the rate of expansion of the period doubling operator at the fixed point.     

Synthesis and photochromic properties of a dithia-dithienylethenophane

The thermally irreversible photochromic compound dithia-dithienylethenophane was synthesized, which is the first example of a dithienylethene bridged with benzene ring and due to the fixation to the photoactive anti-conformation the quantum yield for the photocyclization reaction became higher than that of the corresponding nonbridged type dithienylethene.     

Photochemistry of N‐(2‐Acylphenyl)‐2‐methylprop‐2‐enamides: Competition between Photocyclization and Long‐Range Hydrogen Abstraction

The photochemical reactions of various ‘N‐methacryloyl acylanilides’ (=N‐(acylphenyl)‐2‐methylprop‐2‐enamides) have been investigated. Under irradiation, the acyl‐substituted anilides 1a – 1c and 1o afforded exclusively the corresponding quinoline‐based cyclization products of type 2 (Table 1). In contrast, irradiation of the benzoyl (Bz)‐substituted anilides 1e – 1h afforded a mixture of the open‐chain amides 4e – 4h and the cyclization products 2e – 2h . Irradiation of the para‐acyl‐substituted anilides 6a – 6e and 6h afforded the corresponding quinoline‐based cyclization products of type 5 as the sole products (Table 2). The formation of the cyclization products 2a – 2c and 2o can be rationalized in terms of 6π‐electron cyclization, followed by thermal [1,5] acyl migration, and that of compounds 3p, 5a – 5e , and 5h can be explained by a 6π‐electron cyclization only. The formation of the open‐chain amides 4e – 4h probably follows a mechanism involving a 1,7‐diradical, C and a spirolactam of type D (Scheme). Long‐range ζ‐H abstraction by the excited carbonyl O‐atom of the benzoyl group on the aniline ring is expected to proceed via a nine‐membered cyclic transition state, as proposed on the basis of X‐ray crystallographic analyses (Fig. 2).     

Atom formation processes for cadmium in the presence of sulphur in electrothermal atomization atomic absorption spectrometry with a molybdenum tube atomizer

The atom formation process that occurs during elimination by sulphur of interferences on cadmium in electrothermal atomization was studied by using a thermodynamic-kinetic equation and measuring x-ray diffraction patterns. Activation energies for cadmium in the presence of Al, Ca, Cr, Cu, Fe, K, Na or Pb were obtained in argon-hydrogen in the presence and absence of sulphur. The atom formation process for cadmium in the presence of sulphur was CdS(g) → Cd(g) in the presence of each interferent.     

Synthesis of Indole Derivatives by [2 + 2] Photocycloaddition of Indoline-2-thiones with alkenes and photodesulfurization of indoline-2-thiones

The photochemical synthesis of indole derivatives starting from the indoline-2-thiones 1 is described. Irradiation of indoline-2-thiones 1 in the presence of alkenes 3 gave 2-alkyl-3H-indoles 4 – 7 or 2-alkylindoles 8 – 22 through the ring cleavage of the intermediates, spirocyclic amino-thietanes, initially derived by [2 + 2] cycloaddition of the C?S bond of 1 and the C?C bond of 3 . Irradiation of 1 in the presence of trialkylamines 26 gave desulfurization products 27 – 32 and unexpected 3-alkylindoles 33 – 40 . N-Acylindoline-2-thiones 11 - p yielded the deacylated products, indoline-2-thiones 1a - b , and ethyl esters 43 through γ-H abstraction by the excited thioamide S-atom when irradiated in CDC1₃/EtOH or benzene/EtOH. Oxygen analogues 2a - d also underwent intramolecular H abstraction to give the indolin-2-ones 2e – f and ethyl esters 43 in a similar way.     

Integrated Micro Bio Systems and High Performance Liquid Chromatographic System on Chip

1 Micro chemical system on chip Micro integrated chemical systems are expected as promising ultra high throughput chemical and bio processors with extremely small volume. Our research groups have proposed and developed the original methodologies for micro integration of general chemical systems as well the electropho-     

Continuous wave dye laser excitation spectroscopy CaF A2Πr-X2Σ+

Excitation spectra for the CaF A²Π-X²Σ(0, 0), (1, 1), and (1, 0) bands have been observed and assigned. The rotational analysis of the CaF A-X and B-X bands by B. S. Mohanty and K. N. Upadhya [Ind. J. Pure Appl. Phys.5, 523 (1967)] is shown to be incorrect. Because it is possible to make independent rotational assignments of each line in an excitation spectrum by observing frequency differences and relative intensities in photoluminescence spectra, tunable laser excitation spectroscopy promises less ambiguity than traditional techniques for assignment of dense, badly overlapped spectra.The following spectroscopic constants (in cm^?1) are obtained for the CaF A²Π and X²Σ states. Numbers in parentheses correspond to three standard deviations uncertainty in the last digit.

     

109.

Calcium ions effectively enhance the effect of antisense peptide nucleic acids conjugated to cationic tat and oligoarginine peptides   总被引：4，自引：0，他引：4  

Shiraishi T  Pankratova S  Nielsen PE 《Chemistry & biology》2005,12(8):923-929

Cell-penetrating peptides have been widely used to improve cellular delivery of a variety of proteins and antisense agents. However, recent studies indicate that such cationic peptides are predominantly entering cells via an endosomal pathway. We now show that the nuclear antisense effect in HeLa cells of a variety of peptide nucleic acid (PNA) peptide conjugates is significantly enhanced by addition of 6 mM Ca(2+) (as well as by the lysosomotrophic agent chloroquine). In particular, the antisense activities of Tat(48-60) and heptaarginine-conjugated PNAs were increased 44-fold and 8.5-fold, respectively. Evidence is presented that the mechanism involves endosomal release. The present results show that Ca(2+) can be used as an effective enhancer for in vitro cellular delivery of cationic peptide-conjugated PNA oligomers, and also emphasize the significance of the endosomal escape route for such peptides.     

110.

Electrical conductivities of potassium ferrites doped with divalent metal oxide     

Takehiko Takahashi  Katsumi Kuwabara 《Journal of solid state chemistry》1979,29(1):27-34

The electronic and ionic conduction in three kinds of potassium ferrites with β-alumina structure was studied. Undoped ferrite, K₂O·6Fe₂O₃, prepared by sintering at 1400°C after prefiring a mixture of potassium carbonate and ferric oxide, was a mixed conductor with about 1% ionic conduction and predominantly electronic conduction. The nickel- or zinc-doped potassium ferrite showed decreasing conductivity in the range of a single phase as the content of dopant increased. Variations of the electronic conduction in the doped potassium ferrites were assigned to changes of ferrous ion concentration accompanied by structural changes in the spinel-like blocks. Potassium ion conductivities of the three sorts of samples were estimated from the total conductivities and the transport numbers obtained by dc-polarization technique and electrolysis method. The decreases of the ionic conductivities were explained by narrowing of the alkali-oxygen slot caused by doping.     

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	$\text{X}{}^2\text{Σ}$		$\text{A}{}^2\text{Π}$
$\text{ν}{}_{00}$	0	${}^2\text{Π}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$	16493.1(6)
		${}^2\text{Π}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$	16565.6(6)
$\text{Δ}\text{G(}\text{1}\text{2}\text{)}$	581.1(9)	${}^2\text{Π}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$	586.8(9)
$\text{B}{}_{\mathrm{e}}$	0.3385(11)		0.3436(12)
$\text{B}{}_{\mathrm{e}}\text{(}\text{Ω}\text{=}\text{3}\text{2}\text{) ? B}{}_3\text{(}\text{Ω}\text{=}\text{1}\text{2}\text{)}$	—		0.00312(21)
α	0.00255(48)		0.00283(45)
$\text{D(}\text{estimated}\text{)}$	4.44 × 10?7		4.55 × 10?7
γ(spin-spin)	|γ| < 3 × 10?3		—
$\text{A}{}_0\text{(}\text{spin-orbit}\text{)}$	—		73.4(9)
$\text{p(}\text{lambda doubling}\text{)}$	—		?0.045(4)

Calcium ions effectively enhance the effect of antisense peptide nucleic acids conjugated to cationic tat and oligoarginine peptides

Cell-penetrating peptides have been widely used to improve cellular delivery of a variety of proteins and antisense agents. However, recent studies indicate that such cationic peptides are predominantly entering cells via an endosomal pathway. We now show that the nuclear antisense effect in HeLa cells of a variety of peptide nucleic acid (PNA) peptide conjugates is significantly enhanced by addition of 6 mM Ca(2+) (as well as by the lysosomotrophic agent chloroquine). In particular, the antisense activities of Tat(48-60) and heptaarginine-conjugated PNAs were increased 44-fold and 8.5-fold, respectively. Evidence is presented that the mechanism involves endosomal release. The present results show that Ca(2+) can be used as an effective enhancer for in vitro cellular delivery of cationic peptide-conjugated PNA oligomers, and also emphasize the significance of the endosomal escape route for such peptides.     

Electrical conductivities of potassium ferrites doped with divalent metal oxide

The electronic and ionic conduction in three kinds of potassium ferrites with β-alumina structure was studied. Undoped ferrite, K₂O·6Fe₂O₃, prepared by sintering at 1400°C after prefiring a mixture of potassium carbonate and ferric oxide, was a mixed conductor with about 1% ionic conduction and predominantly electronic conduction. The nickel- or zinc-doped potassium ferrite showed decreasing conductivity in the range of a single phase as the content of dopant increased. Variations of the electronic conduction in the doped potassium ferrites were assigned to changes of ferrous ion concentration accompanied by structural changes in the spinel-like blocks. Potassium ion conductivities of the three sorts of samples were estimated from the total conductivities and the transport numbers obtained by dc-polarization technique and electrolysis method. The decreases of the ionic conductivities were explained by narrowing of the alkali-oxygen slot caused by doping.