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1.
HYDROXYSTILBAZOLES AND HYDROXYAZAPHENANTHRENES: PHOTOCYCLIZATION AND FLUORESCENCE STUDIES 总被引:1,自引:0,他引:1
Abstract— As models for novel fluorescent probes, we have synthesized three isomeric hydroxystilbazole systems (4′-hydroxy-substituted 2-, 3-, and 4-stiIbazoles), examined their photocyclization-oxi-dation to four hydroxyazaphenanthrene systems, and made a preliminary study of their absorption and fluorescence spectra. All three stilbazoles can be prepared easily by addition of the isomeric picoline anions to 4-methoxybenzaldehyde, followed by dehydration and deprotection. Photocyclization proceeds efficiently, furnishing a single product isomer from each of the 2- and 4-stilbazole systems, and two isomeric azaphenanthrenes from the 3-stilbazole. The stilbazoles all have intense UV absorbance bands whose maxima depend upon solvent and pH; all three isomers have relatively similar spectra under neutral conditions and all three show a large red shift in base; in acid, however, the 2-and 4-stilbazole isomers show a greater red shift than the 3-stilbazole. The fluorescence of the stilbazoles is also solvent dependent, shifting to the red in more polar medium; red shifts are also observed in acid and base, but in acid, the 3-stilbazole shows a larger shift. The azaphenanthrene photocyclization products show absorbance spectra typical for quinolines and isoquinolines; their absorptivities are less than the stilbazoles, but their fluorescence is more intense. In general, the benzoquinolines have longer wavelength but weaker fluorescence than the benzoisoquinolines. Also, those isomers in which the resonance effects of the hydroxy and nitrogen groups can reinforce one another show longer wavelength emissions of greater intensity. All seven systems show dual fluorescence in water under neutral conditions, suggesting the emission from both non-ionized and ionized species in the excited state. In one case, the benzoisoquinoline system derived from 4′-hydroxy-4-stilbazole, an emission at 640 nm, observed in water over a wide pH range, is ascribed to a zwitterionic phototautomer. These stilbazoles, benzoquinolines and benzoisoquinolines may prove to be useful spectroscopic probes. 相似文献
2.
p palan BS 《Physical review letters》1987,58(16):1597-1599
3.
Gregory M. Anstead Kathryn E. Carlson Philip R. Kym Kwang-Jin Hwang John A. Katzenellenbogen 《Photochemistry and photobiology》1993,58(6):785-794
Abstract The absorption and emission characteristics of five hydroxytetrahydrochrysenes substituted with acceptor groups (nitro, cyano, methylketone, 1° amide and methyl ester) (THC-NO2, THC-CN, THC-COCH3, THC-CONH2 and THC-CO2CH3, respectively) were investigated in an extensive set of solvents. The order of absorption and fluorescence bathochromicity are: THC-NO2 > THC-COCH3 > THC-CN ≥ THC-CO2CH3 > THC-CONH2 and THC-NO2 >> THC-COCH3 > THC-CO2CH3 > THC-CN > THC-CONH2, respectively. The emission spectra of these compounds are sensitive to the solvent polarity (ET[30] scale) in the order: THC-NO2 > THC-COCH3 > THC-CO2CH3 > THC-CONH2 > THC-CN. The response of the emission maxima of these compounds to the solvent polarity and hydrogen-bond donor/acceptor properties (π*/α/β and acity/basity scales) was also determined. The emission energies of THC-NO2 were most sensitive to π*, β, acity, and basity of the solvent; those of the amide were least sensitive to the solvent π*, β, and basity. The ground- and excited-state dipole moments were determined by semiempirical molecular orbital calculations and the absorption/fluorescence solvent-shift method, respectively. THC-NO2 had the largest ground- and excitedstate moments. The ester and amide had the smallest ground- and excited-state moments, respectively. In general, unsatisfactory results were obtained for correlations of the emission and absorption energies, fluorescence solvatochromism and the ground- and excited-state dipole moments with the Hammett substituent constants of the five acceptor groups. Acceptable correlations were obtained for the absorption and emission energies and the fluorescence solvatochromism with the substituent constants if the cyano compound was excluded. 相似文献
4.
Kim SH Tamrazi A Carlson KE Daniels JR Lee IY Katzenellenbogen JA 《Journal of the American Chemical Society》2004,126(15):4754-4755
We present the first example of a nuclear hormone receptor microarray, using for illustration the ligand-binding domains of the two estrogen receptors, ERalpha-LBD and ERbeta-LBD. The proteins are printed and allowed to attach to aldehyde slides; the efficiency of attachment depends on whether the LBD is liganded with agonists (low attachment) versus liganded with antagonists or unliganded (high attachment). This suggests that attachment is orientation specific and involves principally a single lysine residue. The attached ERs retain good ligand-binding activity that can be assessed using an estradiol-fluorophore conjugate, and specific and ER subtype-selective binding of ligands can be determined conveniently in competitive binding assays. This powerful new, high-throughput technique to study ligand binding to ER-LBDs can be extended to other nuclear hormone receptors and adapted to assay the recruitment of coregulator proteins. 相似文献
5.
Vijaykumar D Mao W Kirschbaum KS Katzenellenbogen JA 《The Journal of organic chemistry》2002,67(14):4904-4910
Two different synthetic routes were explored for the synthesis of fluoro furanyl norprogesterone (FFNP) 1, a high-affinity ligand for the progesterone receptor (PgR) that is being developed as a PET imaging agent for PgR-positive breast cancer. Both approaches proceed through a key intermediate, triol 5. The first approach, starting from keto-ketal 2, employed a dioxenyl group as a synthon for installing a corticosteroid side chain in keto-alcohol 4. The second approach, starting from propargylic acetate 12b, involved the application of a two-step method, a Pd(II)-catalyzed oxidative rearrangement followed by a base-catalyzed acetate rearrangement of the intermediate unsaturated acetate 13b, to generate the requisite corticosteroid side chain in keto-acetate 14b. This intermediate was further elaborated to the final product 1 via efficient dihydroxylation with potassium permangnate, furan acetalization with scandium triflate, and mesylation and fluorination reactions. The palladium-catalyzed route is considerably more efficient than the dioxene approach for the synthesis of key intermediate triol 5, and the scandium triflate-catalyzed acetalization, in particular, led to a considerable improvement in the overall yield of the endo furan acetal alcohol 16a. This route provides a major improvement in the overall yield of the final progestin target, FFNP 1. 相似文献
6.
James S. Wright James M. Anderson Hooman Shadnia Tony Durst John A. Katzenellenbogen 《Journal of computer-aided molecular design》2013,27(8):707-721
The computational determination of binding modes for a ligand into a protein receptor is much more successful than the prediction of relative binding affinities (RBAs) for a set of ligands. Here we consider the binding of a set of 26 synthetic A-CD ligands into the estrogen receptor ERα. We show that the MOE default scoring function (London dG) used to rank the docked poses leads to a negligible correlation with experimental RBAs. However, switching to an energy-based scoring function, using a multiple linear regression to fit experimental RBAs, selecting top-ranked poses and then iteratively repeating this process leads to exponential convergence in 4–7 iterations and a very strong correlation. The method is robust, as shown by various validation tests. This approach may be of general use in improving the quality of predicted binding affinities. 相似文献
7.
A vinylogous Pictet-Spengler cyclization has been carried out using activated aldehydes, ketones, and alkynes to prepare a variety of substituted hexahydrobenzo[f]isoquinolines. A unique set of conditions was utilized to effect efficient cyclization with acid-sensitive electrophiles. 相似文献
8.
Ewa Katzenellenbogen Nina A. Kocharova Georgy V. Zatonsky Maria Bogulska Danuta Witkowska Aleksander S. Shashkov 《Journal of carbohydrate chemistry》2013,32(5):545-558
ABSTRACT Lipopolysaccharide (LPS) of Hafnia alvei 23 has an acid-labile O-specific polysaccharide (OPS) with a pentasaccharide-phosphate repeating unit containing D-Glc1P, D-GlcNAc, L-Fuc, 6-deoxy-D-talose (D-6dTal), 4-acetamido-4,6-dideoxy-D-glucose (D-Qui4NAc), and an O-acetyl group. A partially degraded OPS was obtained by hydrolysis of LPS with 0.25 M sodium acetate in aqueous 0.5% acetic acid. Fractionation of LPS on Sephadex G-200 in DOC buffer allowed isolation of long-chain LPS species which, together with OPS, were studied by methylation analysis, chemical degradations (O-deacetylation, dephosphorylation with 48% hydrofluoric acid, Smith degradation), and 1H and 13C NMR spectroscopy, including 2D COSY, TOCSY, NOESY, and H-detected 1H,13C heteronuclear single-quantum coherence (HSQC) experiments. The following structure of the repeating unit of OPS was established: 相似文献
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Molar extinction coefficients of some carbohydrates viz. l-arabinose (C5H10O5), d-glucose (C6H12O6), d-mannose (C6H12O6), d-galactose (C6H12O6), d(-) fructose (C6H12O6) and maltose (C12H24O12) in aqueous solutions have been determined at 81, 356, 511, 662, 1173 and 1332 keV by gamma ray transmission method in a
narrow beam good geometry set-up. These coefficients have been found to depend upon the photon energy following a 4-parameter
polynomial. These extinction coefficients for different sugars having the same molecular formula have same values varying
within experimental uncertainty. Within concentration ranges studied, Beer-Lambert law is obeyed very well. 相似文献