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- 2012 (6) (entfernen)
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- Alpha-zearalanol (1)
- Crystal structure (1)
- Estrogen (1)
- Growth promoter (1)
- Pyrrole (1)
- Pyrrolovesamicol (1)
- Ralgro (1)
- VAChT (1)
- Vesamicol (1)
- Zearalanone (1)
Eingeladener Vortrag
- nein (2)
Pyrrolovesamicols - synthesis, structure and VAChT binding of two 4-fluorobenzoyl regioisomers
(2012)
This Letter describes the synthesis of two regioisomers of a new class of vesamicol analogs as possible
ligands for imaging the vesicular acetylcholine transporter in future PET studies. The two pyrrolovesamicols
(±)-6a and (±)-6b were synthesized by nucleophilic ring opening reaction of a tetrahydroindole epoxide
precursor with 4-phenylpiperidine. The reaction mechanism of the synthesis was studied by HPLC
and the molecular structures were determined by X-ray structure analysis. Unexpected low binding affinities
to VAChT (Κi = 312 ± 73 nM for (±)-6a and Κi = 7320 ± 1840 nM for (±)-6b) were determined by competitive
binding analysis using a cell line stably transfected with ratVAChT and (–)-[3H]vesamicol.
The asymmetric unit of the title compound, C18H26O5, which is known as α-zearalanol, contains two molecules having the same conformation, with a r.m.s. deviation of less than 0.03 Å for all non-H atoms. In each independent molecule, an intramolecular O—H···O hydrogen bond stabilizes the molecular conformation. In the crystal, O—H···O hydrogen bonds link the molecules, forming infinite chains along [110] and [1¯10].
A hexanuclear Th(IV)–glycine complex was observed by Th L3-edge EXAFS measurements in an aqueous solution. Within the stability range of this complex the positively charged hexanuclear species [Th6(µ3-O)4(µ3-OH)4(H2O)6(Gly)6(HGly)6]6+ was preserved in a crystal with the composition [Th6(µ3-O)4(µ3-OH)4(H2O)6(Gly)6(HGly)6]·(NO3)3(ClO4)3(H2O)3. This complex appears as a result of a competing reaction between hydrolysis and ligation by glycine. At a pH value below the stability range of the hexanuclear complex, crystals with the composition [Th(H2O)3(HGly)3]·(ClO4)4H2O were obtained from the solution. Three water molecules in the thorium coordination sphere indicate that this complex occurs prior to the onset of Th(IV) hydrolysis.
The absolute configuration of the title compound, C18H24O5·H2O, was not been determined by anomalous-dispersion effects, but has been assigned by reference to an unchanging chiral centre in the synthetic procedure. Intramolecular O—H···O hydrogen bonds stabilize the molecular conformation. In the crystal, O—H···O hydrogen bonds link the main molecules and the water molecules, forming an infinite three-dimensional network.