Let F be an arbitrary family of subsets of U and f be a mapping: F→{0,1}, how can we tell whether fz=f for some subset Z of U and how can we construct this Z (or the equivalence class of such Zs)? Here fz:?T∈F,(?).This problem was recognized by D. G. Kendall and the largest element of such Z' s had been established at the same time. In this paper, we shall obtain a class of the minimums and a complete consequence of such Z's by means of F-atom, contacta-bility and relation equation. 相似文献
The compound 4-bromo-3,4-dichloro-1-(1-morpholinyl)-1-(decylsulfanyl)-2-nitro-buta-1,3-diene was synthesized from the reaction
of 4-bromo-1,3,4-trichloro-1-(decylsulfanyl)-2-nitro-buta-1,3-diene with morpholine and characterized by elemental analysis,
IR spectrum, UV spectra, 1H NMR,13C NMR and X-ray single crystal determination. In the title compound, C18H29BrCl2N2O3S, crystallizes in the monoclinic space group P21/c, a = 15.8326(4) Å, b = 8.9915(10) Å, c = 16.7528(5) Å, β = 100.808(10)°, V = 2,342.6(3) Å3, Z = 4, R1 = 0.0590 and wR2 = 0.0940. The morpholine ring adopts a chair conformation. The morpholine ring and the butadiene group are inclined at an
angle of 113.4 (1)°. The butadiene unit is not planar as can be expected if the two double bonds are fully conjugated. 相似文献
A concise approach for the construction of ketene aminals and α-chlorohydrazones has been developed. It involves reactions of the regiodefined gem-dihalo nitrovinyl compound of in situ generated imide chlorides in different media with primary arylamines being dependent on the aryl groups. A range of ketene aminals and α-chlorohydrazones are obtained in good to high yields. In addition, α-aminohydrazones are prepared by using α-chlorohydrazones as the precursors. 相似文献
The substituted products alkyl(aryl)thio-tetrahalo-3-nitrobuta-1,3-dienes 3a–b were obtained from the reactions of 1-bromo-1,2,4,4-tetrachloro-3-nitrobuta-1,3-diene (1) with thiols. Further reactions of the substituted product alkyl(aryl)thio-tetrahalo-3-nitrobuta-1,3-dienes 3a–b in dichloromethane reacted with piperazine derivatives and morpholine to generate 5a–b and 7a–l. The structures of the new compounds were determined by microanalysis and spectroscopic data. 相似文献
Abstract Polyhalogenated nitrobuta-1,3-dienes are unique reagents in organic synthesis and have been employed in several well-known and recently developed areas of application. This study describes the scope and application of 1,1,3,4-tetrachloro-2,4-dinitrobuta-1,3-diene in organic synthesis as well as methods for the preparation of poly- and perfunctionalized 2,4-dinitrobuta-1,3-dienes, and characterization of all obtained compounds. 相似文献
Introducing new biologically active organic molecules or their analogs into the pharmaceutically important molecules significantly enables the discovery and development of the medicines that improve the health of patients. Chemical synthesis has a key role in pharmaceutical research and development, aiming to design and build molecules with the essential biological activity needed in drugs. For that reason, herein, three series of novel PQ analogs (the nonhalogenated (PQ1-6) and the halogenated PQ analogs (BrPQ1-6 and ClPQ1-6)) containing benzocaine and its analogs were designed and synthesized starting from the commercially available dimethylhydroquinone (1) with benzocaine and its analogs. The structures of all synthesized analogs were characterized by using spectroscopic methods. The in vitro antibacterial and antifungal activities were evaluated for the PQ analogs.
Abstract A novel series of substituted 1,4-naphthoquinone derivatives were synthesized and evaluated for their antibacterial and antifungal activity. The structures of the novel products were characterized by spectroscopic methods. Among the tested compounds, 2,2′,3,3′-alkoxy substituted naphthoquinones, S,O-substituted naphthoquinone, and N,S-substituted naphthoquinone derivatives are the most potent antifungals against C. tenuis. 2,3-Thio-2′,3′-alkoxy substituted naphthoquinones are the most effective antifungal compounds against A. niger. Supplemental materials are available for this article. Go to the publisher's online edition ofPhosphorus, Sulfur, and Silicon and the Related Elementsto view the free supplemental file.相似文献