Biomedical subjects
Publications and source records attributed to Thies Thiemann.
The preparation of estrone derived benzothieno- and benzofurano fused steroids is described. Keystep is an intramolecular thienyl(/furyl)-ene-yne cyclization of 16-ethynyl-17-heterarylestra-1,3,5(10),16-tetraenes. The cyclization was carried out under Pt as well as under Ru catalysis.
Thiophene S-oxides have been prepared and their photoreactivity has been studied. In many cases, the sulfur moiety of the thiophene S-oxides is deoxygenated. Here, the corresponding thiophenes or hydroxylated thiophenes are isolated. In the case of the photoirradiation of tert-butyl substituted thiophene S-oxides, the oxygen of the sulfoxy unit is incorporated into the heterocyclic ring system and the corresponding furans have been isolated. Also, structures with two thiophene cores have been oxidized to the respective thiophene S-oxides. These molecules undergo photodeoxygenation, a reaction, which is catalysed by (non-oxidized) thiophenes.
This paper reports unique and unusual formations of columnar liquid crystals and organogels by self-assembling discotic molecules, which are composed of an aromatic hexaazatriphenylene (HAT) core and six flexible aromatic side chains. In HAT derivatives 3a, with 4'-(N,N-diphenylamino)biphenyl-4-yl chains, 3b, with 4'-[N-(2-naphthyl)-N-phenylamino]biphenyl-4-yl chains, and 3c, with 4'-phenoxybiphenyl-4-yl chains, the two-dimensional hexagonal packings can be created by their self-assembling in the liquid crystalline phase, which were characterized by polarizing optical microscopy, differential scanning calorimetry, and X-ray diffraction analysis. In certain solvents, HAT molecules 3a-c can form the viscoelastic fluid organogels, in which one-dimensional aggregates composed of the HAT molecules are self-assembled and entangled into three-dimensional network structures. The organogel structures were analyzed by scanning electron microscopy observation, (1)H NMR, UV-vis, and circular dichroism spectroscopy. In contrast to 3a-c, none of the liquid crystalline and organogel phases could be formed from 3d and 3e with short aromatic side chains including a phenylene spacer, and 3f (except a few specific solutions) and 3g without terminal diarylamino and phenoxy groups. In 3a-c, the aromatic side chains with terminal flexible groups make up soft regions that cooperatively stabilize the liquid crystalline and organogel supramolecular structures together with the hard regions of the hexaazatriphenylene core.
In the title compound, C(33)H(35)NO(2), the five-membered ring adopts a half-chair conformation. The N-methyl-N-phenyl-substituted keto-enamine moiety shows a comparatively long Csp(2)-N bond.
Novel donor-pi-bridge-acceptor-pi-bridge-donor (D-pi-A-pi-D) type 2,1,3-benzothiadiazole fluorescent dyes connected to the N,N-diarylamino terminus via various type pi-conjugate spacers exhibits large two-photon absorption cross-sections and high fluorescent quantum yields in orange-red color.
In the title compound, C21H25N3O, the six-membered ring that is fused to two other six-membered rings in the estrane moiety adopts an envelope conformation. The compound shows intermolecular hydrogen bonding of the amine group to an N atom of the pyrimidine moiety, as well as weak intermolecular interactions involving H atoms in the hydrophobic residue of the molecule.
In the title compound, C(24)H(31)NO(2), ring B adopts a conformation between the boat and twisted-boat forms. This conformation best accommodates adverse intramolecular H.H interactions between the H atoms of the 7beta-substituent and the two nearest ring H atoms. The tilt angle between rings A and D is 28.6 (1) degrees.
Thiophene-S-oxides (thiophene monoxides) are relatively new compounds, less stable than the better-known thiophene-S-dioxides. They are useful as synthons for a range of applications, including in the production of pharmaceuticals. They have interesting photochemical properties, but in this presentation we contrast the electro-oxidative voltammetry of differently substituted derivatives. We also compare carbocyclic compounds such as tetracyclone, the electro-oxidation of which at relatively high potentials has never been reported in silent or insonated conditions.
The preparation of a steroidal heterocycle linked to the tripeptide Cys-Gly-Cys is described. Initially, an estrane-derived steroidal heterocycle containing an aminopyrimidine ring fused to the 16,17-position of the steroidal nucleus was synthesized. Thereafter, protected amino acids were coupled iteratively by the DCC method, commencing at the amino group of the aminopyrimidine unit.
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With ease, eta 6-dihydronaphthalene tricarbonylchromium(0) complexes undergo a triple arylation with concomitant ring closure, when submitted to Heck reactions under 'Jeffery conditions'.
Thiophenes 1 were treated with m-chloroperbenzoic acid (m-CPBA) under BF(3).Et(2)O catalysis to afford thiophene S-monoxides. These could be reacted in situ as intermediary species with a number of dienophiles to provide arenes (with alkynes as dienophiles) or 7-thiabicyclo[2.2.1]hept-2-ene 7-oxides (with alkenes as dienophiles). It was also possible to isolate thiophene S-monoxides in solution and to cycloadd them in a second step. In either way it could be shown that the use of BF(3).Et(2)O enhances the yields of the oxidative cycloaddition of thiophenes considerably. Moreover a greater variety of dienophiles (29a, 29b, 29c) could be reacted with thiophenes than in the case of the noncatalyzed reaction. All cycloadditions catalyzed by BF(3).Et(2)O give only a single diastereoisomer as cycloadduct. The reactions show a high pi-facial selectivity, a fact that can be explained by the Cieplak-effect. Without added dienophiles, 2-methylthiophene (1e) gave a single dimer (36) of 2-methylthiophene S-monoxide, whereas 2,5-dimethylthiophene (1a) gave three dimers (32a-c). In the case of tetrasubstituted thiophenes, thiophene S-monoxides (e.g., 31b and 31c) could be isolated in substance.