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991.
Hiroshi Ohrui Yoshihiro Nishida Hiroshi Hori Hiroshi Meguro Shoji Zushi 《Journal of carbohydrate chemistry》2013,32(4):711-731
Abstract 1-O-Methyl analogs of mucin oligosaccharide components, D-GalNAc (1a and 1b). β-D-Galp-(1-3)-D-GalNAc (2) and β-D-Galp(1-3)-[β-D-GlcNAc-(1-6)]-D-GalNAc (3) in which the H-6proS proton was selectively replaced by a deuterium, were synthesized to study the solution conformations about the C5-C6 fragments by 1H-NMR spectroscopy. The study revealed the preference of the gt-conformer for these sugars. 相似文献
992.
The relationship between the thermal cycloreversion reactivity of diarylethenes and the bulkiness of the substituents at the reactive carbons was systematically investigated. Two photochromic diarylethenes, 1,2-bis(2-isobutoxy-5-phenyl-3-thienyl)perfluorocyclopentene (1a) and 1,2-bis(2-neopentoxy-5-phenyl-3-thienyl)perfluorocyclopentene (2a), were newly synthesized and their optical properties and thermal cycloreversion reactivity were examined, because there is insufficient data for diarylethenes with alkoxy groups at the reactive carbons. The steric substituent constant was employed to correlate the relationship between the thermal cycloreversion reactivity of diarylethenes with alkyl and alkoxy groups at the reactive carbons and the bulkiness of the substituent. A good correlation was obtained for the substituent constant using CH2 instead of oxygen in the alkoxy groups. The results indicate that this is a very useful strategy for the design of novel diarylethenes with desired thermal cycloreversion reactivity. 相似文献
993.
In the organoborane chemistry, the homologation reaction is one of the useful methods for the synthesis of organoboranes not available via hydroboration.1) The allylic boranes are known to be highly reactive and exhibit specific behaviors,2) but with few exceptions,3) these are difficult to be prepared directly by the hydroboration reaction.5) Previously, we reported that in the reaction of the dianion of phenoxyacetic acid with organoborane, the phenoxy group acts as a good leaving group.6) This result suggested us a new homologation reaction converting a saturated organoborane to a allylic borane (1) by the treatment with the carbanion of allyl phenyl ether. Here we wish to report the synthesis of 1-alkenes (II) three-carbon-homologated from starting alkenes7) and the regioselective synthesis of 1,5-dienes (III) using allylic borane intermediates (1) (eq. 1). 相似文献
994.
Highly enantioselective Michael addition of malonates to enones was achieved using a mixed catalyst consisting of a primary β-amino acid, O-TBDPS (S)-β-homoserine, and its lithium salt. Various cyclic and acyclic enones were converted into 1,5-ketoesters in high yields (up to 92%) with high enantioselectivity (up to 97% ee) under mild reaction conditions. Details of synthesis of the catalyst, optimization of the reaction conditions for the Michael addition reaction, and a plausible reaction mechanism are described. 相似文献
995.
One-pot asymmetric synthesis of γ-nitroaldehydes from aldehydes and nitroalkanes was achieved by a catalytic tandem reaction using a primary amino acid lithium salt, O-tert-butyldiphenylsilyl l-tyrosine lithium salt, as a catalyst. Various aryl, alkenyl, and alkyl aldehydes were converted into γ-nitroaldehydes via in situ generation of nitroalkenes. 相似文献
996.
Motomizu S 《Talanta》2011,85(5):2251-2253
997.
Ravinder S Reddy Satoru Iguchi Shoji Kobayashi Masahiro Hirama 《Tetrahedron letters》1996,37(52):9335-9336
Coupling of functionalized cyclopentenyl iodides with ethynyl oxiranes has been achieved by using catalytic amount of Pd(CH3CN)2Cl2 and CuI in the presence of i-Pr2NEt in moderate to good yields. 相似文献
998.
Cyanide is separated from biological bluids by microdiffusion using 1 M acetate buffer (pH 5.2) as an acidifying agent, followed by the fluorimetric determination of the cyanide with naphthalene-2,3-dialdehyde and taurine. The recovery and limit of detection of cyanide in blood and urine are about 70–80% and 0.03 nmol ml?1, respectively. The proposed method for cyanide was successfully adapted for application to blood and urine from smokers and non-smokers. 相似文献
999.
Synthesis of 1,3‐Bis(tetracyano‐2‐azulenyl‐3‐butadienyl)azulenes by the [2+2] Cycloaddition–Retroelectrocyclization of 1,3‐Bis(azulenylethynyl)azulenes with Tetracyanoethylene 下载免费PDF全文
Dr. Taku Shoji Mitsuhisa Maruyama Akifumi Maruyama Prof. Dr. Shunji Ito Dr. Tetsuo Okujima Prof. Dr. Kozo Toyota 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(37):11903-11912
1,3‐Bis(azulenylethynyl)azulene derivatives 9–14 have been prepared by palladium‐catalyzed alkynylation of 1‐ethynylazulene 8 with 1,3‐diiodoazulene 1 or 1,3‐diethynylazulene 2 with the corresponding haloazulenes 3–7 under Sonogashira–Hagihara conditions. Bis(alkynes) 9–14 reacted with tetracyanoethylene (TCNE) in a formal [2+2] cycloaddition–retroelectrocyclization reaction to afford the corresponding new bis(tetracyanobutadiene)s (bis(TCBDs)) 15–20 in excellent yields. The redox behavior of bis(TCBD)s 15–20 was examined by using CV and differential pulse voltammetry (DPV), which revealed their reversible multistage reduction properties under the electrochemical conditions. Moreover, a significant color change of alkynes 9–14 and TCBDs 15–20 was observed by visible spectroscopy under the electrochemical reduction conditions. 相似文献
1000.
Mori H Kamiya M Haemori M Suzuki H Tanaka S Nishio Y Kajita K Moriyama H 《Journal of the American Chemical Society》2002,124(7):1251-1260
The systematic study of band-filling control for four kinds of organic conductors with various kinds of ground states has succeeded. (1) By partial substitution of (GaCl(4))(-) by (MCl(4))(2-) [M = Co, Zn] in the anion blocking layer of lambda-ET(2)(GaCl(4))(-) [ET = bis(ethylenedithio)tetrathiafulvalene], single crystals of lambda-ET(2)(GaCl(4))(-)(1-x)(MCl(4))(2-)(x) [x = 0.0, 0.05, 0.06] have been obtained. The resistivity at room temperature decreases from 3 Omega cm (x = 0.0) to 0.1 Omega cm (x = 0.06) by doping to the antiferromagnet with an effective half-filled band (x = 0.0). (2) Another 2:1 (donor/anion) salt, delta'-ET(2)(GaCl(4))(-), which is a spin gap material, has been doped as delta'-ET(2)(GaCl(4))(-)(1-x)(MCl(4))(2-)(x) [x = 0.05, 0.14]. The resistivity is lowered from 10 Omega cm (x = 0.0) to 0.3 Omega cm (x = 0.14). For both 2:1 salts, the semiconducting behaviors have transferred to relatively conductive semiconducting ones by doping. (3) As for alpha-type 3:1 salts, the parent material is in a charge-ordering state such as alpha-(ET(+)ET(+)ET(0))(CoCl(4))(2-)(TCE), where the charge-ordered donors are dispersed in the two-dimensional conducting layer. Although the calculation of alpha-ET(3)(CoCl(4))(2-)(TCE) shows a band-insulating nature, and the crystal structure analysis indicates that this material is in a charge-ordering state, the metallic behavior down to 165 K has been observed. With doping of (GaCl(4))(-) to the alpha-system, isostructural alpha-ET(3)(CoCl(4))(2-)(1-x)(GaCl(4))(-)(x)(TCE) [x = 0.54, 0.57, 0.62] have been afforded, where the pattern of the horizontal stripe-type charge ordering changes with an increase of x. (4) By doping (GaCl(4))(-) to the 3:2 gapless band insulator which is isostructural to beta'-ET(3)(MCl(4))(2)(2-) [M = Zn, Mn], the obtained beta'-ET(3)(CoCl(4))(2-)(2-x)(GaCl(4))(-)(x) [x = 0.66, 0.88] shows metallic behavior down to 100 and 140 K, respectively. They are the first metallic states in organic conductors by band-filling control of the gapless band insulator. These systematic studies of band-filling control suggest that the doping to the gapless band insulator with a pseudo-1/2-filled band is most effective. 相似文献