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31.
An efficient asymmetric synthesis of selective estrogen receptor β-modulator (S)-4-bromo-9a-butyl-8-chloro-6-fluoro-7-hydroxy-1,2,9,9a-tetrahydro-fluoren-3-one was developed. The route features a chemoselective aromatic chlorination reaction, an asymmetric phase-transfer-catalyzed alkylation of an indanone with efficient ee upgrade by racemate crystallization, and a robust bromination reaction using imidazole as an in situ bromine trap to avoid overreaction. The synthesis proceeds in 34% yield over 8 steps from 2-fluoroanisole, and provides material with >99.5% ee. 相似文献
32.
Ronald G. Sutherland Adam Pirko Choi Chuck Lee Stanley H. Simonsen Vincent M. Lynch 《Journal of heterocyclic chemistry》1988,25(6):1911-1916
Synthesis of the heterocyclic skeletons of some biologically active compounds from (η6-o-dichlorobenzene)(η5-cyclopentadienyrl)iron hexafluorophosphate in a two step procedure is described. Cyclopentadienyliron hexafluorophosphate complexes of 1,4-benzodioxino[2,3-b]pyridine, 1,4-benzoxathiino[3,2-b]pyridine, 10H-pyrido[3,2-b]benzoxazine, benzo[b]naphtho[2,3-e][1,4]dioxin, 4-methylbenzo[b]benzopyran-2-one[7,6-e][1,4]dioxin and benzo[b]anthracen-9,10-diono[1,2-e][1,4]dioxin were isolated and characterized. Upon pyrolytic sublimation of these complexes the free heterocycles were obtained and characterized. (η6-1,4-Benzoxathiino[3,2-b]pyridine)(η5-cyclopentadienyl)iron hexafluorophosphate crystalizes in the orthothombic system, space group Pbca; the dihedral angle between the planes of outer rings was found to be 176.8 (1). 相似文献
33.
Lynch CL Hale JJ Budhu RJ Gentry AL Finke PE Caldwell CG Mills SG MacCoss M Shen DM Chapman KT Malkowitz L Springer MS Gould SL DeMartino JA Siciliano SJ Cascieri MA Carella A Carver G Holmes K Schleif WA Danzeisen R Hazuda D Kessler J Lineberger J Miller M Emini E 《Organic letters》2003,5(14):2473-2475
[reaction: see text] A novel approach to alpha,alpha-disubstituted-beta-amino acids (beta(2,2)-amino acids) was employed in the synthesis of a series of 3-(pyrrolidin-1-yl)propionic acids possessing high affinity for the CCR5 receptor and potent anti-HIV activity. The rat pharmacokinetics for these new analogues featured higher bioavailabilities and lower rates of clearance as compared to cyclopentane 1. 相似文献
34.
Sessler JL Tomat E Mody TD Lynch VM Veauthier JM Mirsaidov U Markert JT 《Inorganic chemistry》2005,44(7):2125-2127
The coordination chemistry of the Schiff base polypyrrolic octaaza macrocycle 1 toward late first-row transition metals was investigated. Binuclear complexes with the divalent cations Ni(II), Cu(II), and Zn(II) and with the monovalent cation Cu(I) were prepared and characterized. Air oxidation of the Cu(I) ions in the latter complex to their divalent oxidation state resulted in a change in the coordination mode relative to the macrocycle. 相似文献
35.
Gel swelling experiments have been used to study the binding of ionic surfactants to a series of nonionic alkylacrylamide hydrogels of increasing hydrophobicity. The binding of hexadecyl trimethylammonium (C16TA+) to uncharged gels is sensitive to both the hydrophobicity of the gel and the counterion to the surfactant. There is a minimum hydrophobicity threshold below which binding of the surfactant does not occur, and this is influenced by the counterion to the surfactant. The surfactant concentration at the onset of binding, the critical association concentration (cac), decreases with increasing gel hydrophobicity. The maximum swelling of the gel (at intermediate network hydrophobicity) increases in the order of the Hofmeister series of anions, bromide (Br-) < chloride (Cl-) < acetate (Ac-). At higher gel hydrophobicity, differences in swelling are no longer observed on changing the counterion. A minimum hydrophobicity threshold was also found for the binding of the anionic surfactants sodium dodecyl sulfate (SDS) and sodium dodecyl-di(ethylene oxide)-sulfate (SD-(EO)2-S). Differences in the swelling behavior with network hydrophobicity are explained in terms of the degree of saturation of the gel with surfactant at the cmc. 相似文献
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38.
We describe the structure in aqueous solution of an extended-size DNA-like duplex with base pairs that are approximately 2.4 A longer than those of DNA. Deoxy-lin-benzoadenosine (dxA) was employed as a dA analogue to form hydrogen-bonded base pairs with dT. The 10mer self-complementary extended oligodeoxynucleotide 5'-d(xATxAxATxATTxAT) forms a much more thermodynamically stable duplex than the corresponding DNA sequence, 5'-d(ATAATATTAT). NMR studies show that this extended DNA (xDNA) retains many features of natural B-form DNA, but with a few structural alterations due to its increased helical diameter. The results give insight into the structural plasticity of the natural DNA backbone and lend insight into the evolutionary origins of the natural base pairs. Finally, this structural study confirms the hypothesis that extended nucleobase analogues can form stable DNA-like structures, suggesting that alternative genetic systems might be viable for storage and transfer of genetic information. 相似文献
39.
Wing W. Lam Gary E. Martin Vincent M. Lynch Stanley H. Simonsen Charles M. Lindsay Keith Smith 《Journal of heterocyclic chemistry》1986,23(3):785-791
The synthesis of 2-azathianthrene ([1,4]benzodithiino[2,3-c]pyridine), the only remaining monoazathianthrene yet to be reported, is described. Attempts at the direct condensation of disubstituted pyridines with the dianion of 1,2-dimercaptobenzene were generally unsuccessful requiring that the alternative condensation of the dianion with disubstituted pyridine 1-oxides be employed. The title compound was characterized by physical means including 13C-nmr spectroscopy. One analog, 4-nitro-2-azathianthrene was also studied by X-ray crystallographic means; the molecule crystallized with two molecules in the asymmetric unit P21/n, a = 20.712(3), b = 7.8109(13), c = 13.720(2)Å, β = 107.880(11)°, Z = 8, the data refined to a final R = 0.051 for 3061 reflections. Dihedral angles between the planes of the phenyl rings were 135.00(13) and 132.52(13)° for the two independent molecules contained in the crystal. Close non? bonded S ?O intramolecular contacts were observed in both molecules between the sulfur and nitro-group oxygens. Both nitro groups are twisted out of the plane of the pyridine ring and are oriented at angles of 28.75 and 38.82° respectively. 相似文献
40.
Sessler JL Cho WS Lynch V Král V 《Chemistry (Weinheim an der Bergstrasse, Germany)》2002,8(5):1134-1143
The synthesis and structural characterization of hybrid heterocalix[4]arene analogues containing pyrrole, benzene, methoxy-substituted benzene, and pyridine subunits is described. Macrocycles 1 and 2, examples of calix[2]benzene[2]pyrrole and calix[1]benzene[3]pyrrole systems, respectively, are synthesized by the condensation of pyrrole and an appropriate phenylbis(carbinol). Macrocycles 3 and 7, examples of calix[2]benzene[1]pyridine[1]pyrrole and calix[1]pyridine[3]pyrrole, respectively, are synthesized by the use of a carbene-based pyrrole-to-pyridine ring-expansion procedure. Single-crystal X-ray analysis reveals that compounds 1a, 1b, and 2b adopt 1,3-alternate conformations in the solid state, whereas compounds 3 and 7 display structures that are best described as "flattened partial cones" in terms of their conformation. (Series a refers to pure benzene-derived systems, whereas series b indicates macrocycles containing 5-methoxyphenyl subunits). In the solid state, the methoxy-functionalized macrocycles 1b and 2b, and the chloropyridine-containing macrocycle 7 exist as dimers. In the case of 1a and 7, these compounds interact with neutral solvent in the solid state. The conformations of the macrocycles in solution were explored by temperature-dependent proton NMR and NOESY spectral analysis. At 188 K, macrocycles 1a and 2a adopt flattened 1,3-alternate conformations, whereas macrocycles 3 and 7 exist in the form of flattened partial-cone conformations. Standard proton NMR titration analyses were carried out in the case of macrocycles 1a and 2a, and reveal that at least the second of these systems is capable of binding fluoride and chloride anions in CD(2)Cl(2) solution at room temperature (K(a)=571 and 17M(-1) in the case of 2a and F(-) and Cl(-), respectively). 相似文献