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101.
Harding WW Tidgewell K Schmidt M Shah K Dersch CM Snyder J Parrish D Deschamps JR Rothman RB Prisinzano TE 《Organic letters》2005,7(14):3017-3020
[reaction: see text] Two new neoclerodane diterpenes, salvinicins A (4) and B (5), were isolated from the dried leaves of Salvia divinorum. The structures of these compounds were elucidated by spectroscopic techniques, including (1)H and (13)C NMR, NOESY, HMQC, and HMBC. The absolute stereochemistry of these compounds was assigned on the basis of single-crystal X-ray crystallographic analysis of salvinicin A (4) and a 3,4-dichlorobenzoate derivative of salvinorin B. 相似文献
102.
Zhu H Chai J Chandrasekhar V Roesky HW Magull J Vidovic D Schmidt HG Noltemeyer M Power PP Merrill WA 《Journal of the American Chemical Society》2004,126(31):9472-9473
The reaction of beta-diketiminated aluminum(I) monomer LAl with a large bulky azide N3Ar' (L = HC(CMeNAr)2, Ar' = 2,6-Ar2C6H3, Ar = 2,6-iPr2C6H3) in the temperature range from -78 degrees C to room temperature affords two different isomers 2 and 3, which have been characterized by spectroscopic and X-ray structural analyses, as well as elemental analysis. The variable-temperature 1H NMR kinetic studies of this reaction indicate the existence of the monomer LAlNAr' (1) at low temperature and the thermal stability of the compounds increases in the order of 1 < 2 < 3. 相似文献
103.
Haijun HaoHerbert W. Roesky Yuqiang DingChunming Cui Mark SchormannHans-Georg Schmidt Mathias NoltemeyerBoris ?emva 《Journal of fluorine chemistry》2002,115(2):143-147
β-Diketiminato magnesium fluoride [{CH(CMeNAr)2}Mg(μ-F)(THF)]2·toluene (Ar=2,6-i-Pr2C6H3, 2·toluene) was synthesized. The molecular structure of 2 revealed for the first time, the double fluoro bridge feature between the two magnesium atoms with a typical MgF bond length (average 1.95 Å). 相似文献
104.
D. Rosmann K. -W. Klinkhammer A. Schmidt 《Monatshefte für Chemie / Chemical Monthly》1996,127(5):461-468
Zusammenfassung Arsen-tris(2,2-dimethylpropionat) (1) kristallisiert monoklin in der Raumgruppe P21/n mita=926.2,b=2158.6,c=983.7 pm, =94.92° undZ=4. As hat gegenüber O die Koordinationszahl 3+3. Antimontripropionat (2) kristallisiert monoklin in der Raumgruppe P21/c mita=930.2,b=863.0,c=1575.2 pm, =90.27 undZ=4. Die Moleküle sind intermolekular zu Ketten verknüpft, wodurch Sb die Koordinationszahl 3+3 (+3) erreicht.
Structure of arsen(III) and antimony(III) carboxylates
Summary Arsen-tris(2,2-dimethylpropionate) (1) crystallizes monoclinic in the space group P21/n witha=926.2,b=2158.6,c=983.7 pm, =94.92°, andZ=4. As has a coordination number of 3+3. Antimony tripropionate (2) crystallizes monoclinic in the space group P21/c witha=930.2,b=863.0,c=1575.2 pm, =90.27, andZ=4. The molecules are bridged to chains; therefore, Sb reaches the coordination number 3+3 (+3).相似文献
105.
Lone Skov Henrik Hansen Henning C. Dittmar Jonathan N. W. N. Barker Jan C. Simon Ole Baadsgaard 《Photochemistry and photobiology》1998,67(6):714-719
Sensitization on skin exposed to acute low-dose UVB irradiation separates normal humans into two phenotypically distinct groups: One group, following sensitization on UVB-irradiated skin, develops contact sensitivity, designated UVB resistant (UVB-R) and the second group, following sensitization on UVB-irradiated skin, fails to develop contact sensitivity, designated UVB susceptible (UVB-S). To investigate whether UVB susceptibility in humans is related to antigen-presenting activity in the skin we studied the effect of UVB irradiation on the number and function of the epidermal antigen-presenting cells in volunteers identified as UVB-R and UVB-S. Single cell suspensions of epidermal cells from control skin and skin exposed to 3 minimal erythema doses (MED) of UVB 3 days previously were stained for Langerhans cells (CD1a+HLA-DR+) and epidermal macrophages (CD1a-HLA-DR+). The UVB exposure of the skin significantly decreased the percentage of Langerhans cells (UVB-R: n = 7, P < 0.02, UVB-S: n = 6, P < 0.03) and increased the percentage of epidermal macrophages (UVB-R: n = 7, P < 0.03, UVB-S: n = 6, P < 0.03) however to the same degree in both the UVBR and the UVB-S group. To study the effect on Langerhans cell alloreactivity, epidermal cells were harvested immediately after UVB irradiation. However, in both UVB-R and UVB-S subjects the Langerhans cell alloreactivity was blocked to the same degree immediately after UVB irradiation compared to nonirradiated epidermal cells. To determine the effect of UVB irradiation on epidermal macrophages, epidermal cells were harvested 3 days after UVB irradiation. Irradiated epidermal cells from both UVB-R and UVB-S subjects demonstrated a strong antigen-presenting capacity compared to epidermal cells from control skin leading to activation of T cells that mainly secrete interferon (1FN)-γ and not interleukin (IL)-4. In conclusion we found that UVB susceptibility was not correlated with the number of Langerhans cells or epidermal macrophages in the skin at the same time of sensitization. Neither was it correlated with the capacity of Langerhans cells nor UVB-induced epidermal macrophages to activate T cells in vitro. 相似文献
106.
Reaction Products of Antimony(V) Chloride and N, N′-Dimethyloxamide and their Vibrational Spectra N, N′-Dimethyloxamide reacts with antimony(V) chloride at lower temperatures to the 1:1 resp. 1:2 addition compounds I resp. II. Pyrolysis of these compounds leads to the cyclic tetrachloroantimony(V)-N, N′-dimethyloxamides (III) resp.(V). III yields with antimony(V) chloride the 1:1 adduct IV, which is transformed to V. The vibrational spectra were assigned and discussed. 相似文献
107.
Fiedler SL Vaskonen KJ Eloranta JM Kunttu HM 《The journal of physical chemistry. A》2005,109(20):4512-4516
Electronic spectroscopy of the C(2) molecule is investigated in Ar, Kr, and Xe matrixes in the 150-500 nm range. In the Ar matrix, the D ((1)Sigma(u)(+)) <-- ((1)Sigma(g)(+)) Mulliken band near 240 nm is the sole absorption in the UV range, whereas in the Kr matrix additional bands in the 188-209 nm range are assigned to the Kr(n)()(+)C(2)(-) <-- Kr(n)()C(2) charge-transfer absorptions. Because of the formation of a bound C(2)Xe species, the spectral observations in the Xe matrix differ dramatically from the lighter rare gases: the Mulliken band is absent and new bands appear near 300 and 423 nm. The latter is assigned to the forbidden B'((1)Sigma(g)(+)) <-- X ((1)Sigma(g)(+)) transition, but the origin of the former remains unclear. The spectral assignments are aided by electronic structure calculations at the MCSCF, CCSD(T), and BCCD(T) levels of theory and correlation consistent basis sets. A significant presence of multireference character of the C(2)Xe system was noted and a linear ground-state structure is predicted. The computational results contradict previous density functional studies on the same system. 相似文献
108.
On Calcium Bromated and Iodates – Crystal Structure, X-Ray, IR and Raman Spectroscopical and Thermoanalytical Investigations The phase relationships (and both decomposition and disproportionation)of bromates and iodates of alkaline earth metals are studied by means of thermal analyses (DTA, DSC, TG) and (high-temperature) X-Ray, IR-, and (high-temperature) Raman spectroscopic measurements. The following compounds have been established: Ca(IO3)2 · 6 H2O oF 216, the isotypic Ca(BrO3)2 · H2O and Ca(IO3)2 · H2O mP 48, Ca(IO3)2 I (Lautarit) mP 36, Ca(IO3)2 II and Ca(BrO3)2. The Crystal structure of Ca(IO3)2 · H2O (brüggenite) (space group P21/c, Z = 4) has been determined by single crystal X-ray diffraction (MoKα). The final R value for 3888 reflections with Io > 3σ1 is 0.0487. The structures of bromates and iodates of alkaline earth metals known so far are discussed with respect to the energetic (mode frequencies) and geometric (bond lengths) distortion of the XO3–ions as well as the strengths of H-bonds present in the respective hydrates. 相似文献
109.
1-(5-Nitro-2-thiazolyl)-2-imidazolidinone is synthesized from 2-amino-5-nitro-thiazole and 2-chloroethyl-isocyanate. The structure of this new potent schistosomicide is established by acid and alkaline degradation as well as by synthesis starting from 2-imidazolidinone. A number of derivatives of 1-(5-nitro-2-thiazolyl)-2-imidazolidinone are reported. 相似文献
110.
Schmidt A Habeck T Merkel L Mäkinen M Vainiotalo P 《Rapid communications in mass spectrometry : RCM》2005,19(16):2211-2216
Pyrazolium-3-carboxylate and indazolium-3-carboxylate, which belong to the class of pseudo-cross-conjugated mesomeric betaines and which represent the electronically relevant partial structures of the betaine alkaloid Nigellicin, were examined by electrospray ionization mass spectrometry. These compounds decarboxylate to pyrazol-3-ylidene and indazol-3-ylidene. The formation of adducts of these new nucleophilic carbenes under the measurement conditions was examined. 相似文献