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Methyl (3,6-dichloropyridazin-4-yl)acetate (II), prepared from methyl (3,6-dihydroxypyrid-azin-4-yl)aeetate (1) by chlurination with phosphorus oxychloride, was used for studies of nucleo-philic displacement reactions and it has been found that only the chlorine atom at position 6 was displaced with hydrazine. With diluted hydrochloric acid both chlorine atoms were displaced with the 6-oxo isomer predominating. By turning the aromatic ring of pyridazine into an o-quinoid system, the chlorine atom at position 3 became mobile. Cyelization of (6-hydrazino-s-triazolo-[4,3-b ]pyridazin-7-yl)acetic acid hydrazide (XIX) gave 6-aminopyrrolo[3,2-e ]s-triazlo[ 4,3-b ]-pyridazm-7(8H)one (XXI). 相似文献
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Tetraacetylethylene (1) reacted with electron-withdrawing azo compounds to give spiro furan-pyrazoles. Their structure was confirmed by an X-ray crystallographic analysis on a derivative of the spiro furan-3(2H),5′(7′H)-pyrazolo 1,2-a1,2,4 triazole-1′,3′,6′-trione. The cycload-ducts show ring-open chain tautomerism. 相似文献
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Di-t-butyl nitroxide readily substitutes alkyl zirconocenes and hafnocenes, Cp2MR2, by a rate-determining displacement of alkyl radicals to give high yields of O-alkyl-N,N-di-t-butylhydroxylamine and Cp2M(R)ONBut2. A free radical substitution of di-benzylzirconocene by benzenethiyl radicals yields Cp2Zr(SPh)2. 相似文献
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The technique of ferromagnetic resonance at 23 GHz has been used to determine the first three anisotropy constants of pure Ni down to 4.2K. A temperature and orientation dependent linewidth has also been observed. 相似文献
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We show that composite de novo structures can be generated using bio-electrosprays. Mouse lung fibroblasts are bio-electrosprayed directly with a biopolymer to form cell-bearing matrices, which are viable even when implanted subcutaneously into murine hosts. Generated cell-bearing matrices are assessed in-vitro and found to undergo all expected cellular behaviour. Subsequent in-vivo studies demonstrate the implanted living matrices integrating as expected with the surrounding microenvironment. The in-vitro and in-vivo studies elucidate and validate the ability for either bio-electrosprays or cell electrospinning to form a desired living architecture for undergoing investigation for repairing, replacing and rejuvenating damaged and/or ageing tissues. 相似文献
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Giorgio Adembri Donato Donati Lucia R. Lampariello Mirella Scotton Alessandro Sega 《Tetrahedron letters》1984,25(52):6055-6058
The stereochemistry of (1a,4β,5a)-1,5-diacetyl-4-hydroxy-4-methylbicyclo[3.1.0]hexan-2-one, the main cycloadduct of 2,3-diacetyl-4-hydroxy-4-methylcyclopent-2-en-1-one and diazomethane, was unambiguously established from a single crystal X-ray analysis. 相似文献