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911.
α-Halogeno ethers, sulfides, and amines are reactive compounds which can be used for the formation of new C? C bonds, either as nucleophilic or as electrophilic reagents, or by α-elimination. The use of these compounds in the synthesis of many classes of organic compounds is reviewed. 相似文献
912.
C. Hamon J. D. Soilan-Rodriguez H. Kalchhauser W. Reischl 《Monatshefte für Chemie / Chemical Monthly》1997,128(12):1297-1300
Summary When the benzoate of (S)-(Z)-2-(5-(tert-butyldimethylsiloxy)-2-methylencyclohexyliden)-ethanol (5) is treated with 2.5 equivalents of Hg(OOCCF3)2 in dryTHF, a smooth and selective allylic hydroxylation occurs. The C-1 functionalized vitamin D A-ring synthon6 is isolated in 65 to 70% yield in a single step.
Hydroxylierung eines Vitamin D A-Ring-Fragments (Kurze Mitt.)
Zusammenfassung Umsetzung des Benzoats von (S)-(Z)-2-(5-(tert-Butyldimethylsiloxy)-2-methylencyclohexyliden)-ethanol (5) mit 2.5 Äquivalenten Hg(OOCCF3)2 in trockenemTHF führt zu einer selektiven allylischen Hydroxylierung. Damit ist das an C-1 funktionalisierte Vitamin D A-Ring-Fragment6 in einem einzigen Schritt in einer Ausbeute von 65 bis 70% zugänglich.相似文献
913.
Jue Xiao CAI Zheng Hong ZHOU Kang Ying LI Chi Hung YEUNG Chu Chi TANG* State Key Laboratory of Elemento-Organic Chemistry Institute of Elemento-Organic Chemistry Nankai University Tianjin Open Laboratory of Chirotechnology D 《中国化学快报》2002,13(7)
Optically active 1,1-binaphthalene-2, 2-diol has become a quite important chiral source in different fields of chirotechnology, especially in asymmetric synthesis1. Its synthesis and resolution has been extensively studied and various resolution methods have been reported2. Among the reported resolution methods, the following three, namely, via the formation of phosphoric acid derivatives3, boric acid derivatives4 and inclusion complexes5, are the most important. OHOH+_( )-1(-)-(S)-1(+)-(R)… 相似文献
914.
The formal synthesis of antimicrobial diterpene udoteatrial hydrate (1) is described in nine steps. Diol 6 used as starting material. The key intermediate 4 was obtained from bicyclic ketone 5 via the key Norrish type I reaction. 相似文献
915.
Ab initio calculation of the 4-ClC6H4CH2Cl molecule was performed by the restricted Hartree-Fock method in the split valence 6–31 G* basis set with complete optimization of its geometry. Populations of p-orbitals of atoms of this molecule were analyzed.35Cl NQR frequencies and asymmetry parameters of the electric field gradient on35Cl nuclei were estimated on the basis of the populations of valent p-orbitals of CI atoms and their components. Good conformity with the experimental values was obtained when only less diffuse components of p-orbitals were used in calculations of populations.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 823–826, April, 1996. 相似文献
916.
《Electroanalysis》2004,16(21):1763-1770
The electrochemical behavior of the nitrofuran antibiotics nitrofurantoin (NFA) and nitrofurazone (NFZ), as well as the related nitroimidazole drug, metronidazole (MNZ) at electrochemically activated carbon fibre microelectrodes (CFMEs) is reported. These nitrofurans have been widely used in the form of feed additives for the treatment of gastrointestinal infections in cattle, pigs and poultry. Electrochemical activation of CFMEs by repetitive square‐wave (SW) voltammetric scans between 0.0 and +2.6 V, produced an unexpected high cathodic response from these compounds. This is attributed to the increase of the carbon fibre surface area due to its fracture and the appearance of deep fissures along the main fibre axis. Penetration of the nitroderivative compounds into the micro‐channels of the activated fibres was profited to develop a sensitive and selective method for NFA based on stripping SW voltammetry. The metabolite of NFA, 1‐aminohydantoin (AHD), did not exhibit cathodic response in the potential range between ?0.9 and +0.1 V. However, AHD gave a SW oxidation signal at activated CFMEs, with a potential of +0.95 V, which did not appear at non‐activated microelectrodes. Based on this finding, the simultaneous determination of NFA and AHD was performed by amperometry using two activated CFMEs in a parallel configuration connected to a multichannel detector. This methodology was also used to carry out degradation studies of NFA in acidic and basic media under photodegradation or thermal degradation conditions. 相似文献
917.
918.
Ariza-Castolo A Montalvo-González JA Montalvo-González R 《Magnetic resonance in chemistry : MRC》2005,43(12):975-978
The configurational properties of a series of cyclohexylidene imines are discussed on the basis of their 1H, 13C and 15N NMR spectral data. 相似文献
919.
Introduction 2-Hydroxy-1,4-naphthoquinone (HNQ), existing in natural plants,1,2 is popularly separated and purified as dye or pigment. Recent research results show that, with the function to prevent the formation of protein coenzyme of HIV-I, HNQ can inhibit HIV virus from copying and propagating,3,4 HNQs derivatives and di-chloroallyl lawsone are also the inhibitor for RNA syn-thesis of cancer.5 It is well known that there is a rela-tionship between the side chain attached to HNQ an… 相似文献
920.