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101.
Treatment of N-heteroarylacethydrazides with an equimolar amount of nitrous acid afforded N-heteroaryacetylazides and subsequent thermolysis of these azides gave the analogues of 2,3-dihydroimidazo[1,5-a]pyridin-3-one. When some of these cyclized compounds were treated with nitrous acid, the ring opening reaction occurred and recyclized 3-(N-heteroaryl)-1,2,4-oxadiazolin-5-ones were obtained. Treatment of N-heteroarylacethydrazides with two equivalent moles of nitrous acid afforded α-oximino-α-(N-heteroaryl)acetylazides. Thermolysis of these azides gave mixtures of 3-(N-heteroaryl)-1,2,4-oxadiazolin-5-one and 3-hydroxy-4-(N-heteroaryl)furazan. On the basis of the effects of heterocyclic rings and solvents upon the relative yield of two types of the products, one plausible mechanistic explanation for the decomposition of such azides was proposed. α-Oximino-α-(H-heteroaryl)acetylazides were converted into cyano N-heterocycles by the action of alkali in good yields. 相似文献
102.
103.
A new xanthone diglucoside (1) has been isolated from the aerial parts of Swertia perennis L. (Gentianaceae) by means of column chromatography on polyamide, followed by preparative TLC. on silica gel. From UV. and NMR. data, its structure has been established as 1,3-di-β-D -glucopyranosyl-7,8-dihydroxyxanthone or norswertianine-1,3-diglucoside. 相似文献
104.
Iwao?KatayamaEmail author Adolf?Mikula Toshio?Oishi 《Monatshefte für Chemie / Chemical Monthly》2005,136(10):1715-1725
Summary. Gallium activity in the B2 (CsCl-type) phase of ternary Co–Ga–X (X = Ge, Ni, and Fe) alloys was measured by the EMF method with a stabilized zirconia solid electrolyte. The temperature range
was 1050–1250 K and the concentrations of the added elements were 2–6 at-% Ge and Ni, and 1–3 at-% Fe. The reference electrodes
were Fe,FexO or Ga,Ga2O3. The effect on the activity of gallium in the B2 phase with the addition of other elements was found to be the largest with
Ge and the smallest in the case of Ni. 相似文献
105.
[reaction: see text] Novel C2-C3'N-linked macrocyclic taxoids are synthesized using intramolecular Heck reaction in the key step. Macrocyclization proceeds with high regioselectivity in good yield. Taxoids bearing an olefin moiety at C2 and an iodide at C3'N give exo-products exclusively. However, the endo-products are formed with up to 100% regioselectivity just by switching the positions of the olefin and the iodide moieties. Some of these macrocyclic taxoids are significantly cytotoxic. 相似文献
106.
[Ac-D-Tyr1, D-Ala2, Leu5-OMe]Enkephalin and [Ac-Tyr1, D-Ala2, Leu5-OMe]Enkephalin were successfully synthesized by the coupling of dipeptide units and tripeptide units which were readily obtained by the asymmetric hydrogenation of the corresponding dehydropeptide building blocks. 相似文献
107.
Ji-Ben Meng Wen-Guang Wang Hong-Gen Wang Teruo Matsuura Hideko Koshima Iwao Sugimoto Yoshikatsu Ito 《Photochemistry and photobiology》1993,57(4):597-602
Abstract— Solid-state irradiation of mixed crystals prepared by meltinga 1:3 molar mixture of indole and phenanthrene followed by resolidifying the melt gave an adduct 2a in 13.5% yield. An adduct 2b was obtained by irradiation of the mixed crystals of 3-methylindole and phenanthrene. Irradiation of the same mixtures of indoles and phenanthrene in solution gave no photoproduct. Irradiation of the mixed crystals of indole and naphthalene gave a similar photoadduct 3a, which was also formed in solution. The 1:1 mixed crystals of indole and phenanthrene and of indole and naphthalene were characterized by various spectroscopic methods. Among them powder X-ray diffraction spectral analysis and differential scanning calorimetry revealed that the former mixed crystal is a simple mixture of microcrystals of indole and phenanthrene, while the latter forms a molecular compound. 相似文献
108.
Iwao Okamoto Mayumi Nabeta Akio Nakashima Tetsuya Takeya Isao Azumaya 《Tetrahedron letters》2007,48(4):573-577
Aromatic N-methyl amides containing N-(2-pyridyl) and 2-pyridinecarboxamide or 2,6-pyridinedicarboxamide moieties switch their conformation from cis to trans depending upon the addition of acid. 相似文献
109.
Iwao Ojima Shin-Ichi Inaba Tetsuo Kogure Yoichiro Nagai 《Journal of organometallic chemistry》1973,55(1):C7-C8
Dibromomethyllithium and its homologues RCBr2Li (R = Bu, Me3Si, Br) are prepared by metallation of the corresponding α,α-dibromo compounds with lithium diisopropylamide in THF at low temperature. Various coupling reactions are described (alkylation, hydroxyalkylation). New one-step preparations of α-bromoepoxides and α-bromoketones are reported. 相似文献
110.
We give a determinant expression for the Bartholdi zeta function of a digraph which is not symmetric. This is a generalization of Bartholdi’s result on the Bartholdi zeta function of a graph or a symmetric digraph. 相似文献