The crystal structure and absolute configuration of (−)-dihydroergotamine methanesulfonate monohydrate

Fast energy minimization of the CCDC drug-subset structures by molecule-in-cluster computations allows independent structure validation and model completion

Optimizing structures with computations on clusters of molecules permits generation of structure-specific restraints for refinement and structure validation.

Outlining migrainous through dihydroergotamine–serotonin receptor interactions using quantum biochemistry

We present the electronic structure of the complex dihydroergotamine–serotonin receptor to unveil new medications to treat migraine and related diseases.

Conformation of ergopeptam and ergopeptine alkaloids (ergocristam and ergocristine)

The crystal structures of two ergot alkaloids ergocristam (I) and ergocristine acetone solvate (II), have been determined by X-ray diffraction and compared with their conformation in solution obtained from NMR data. The presence of D-proline in I essentially influences the conformation of the alkaloid tripeptide moiety which seems likely to explain why I does not undergo further enzymatical hydroxylation and is found as a terminal step of ergot alkaloid biosynthesis.

Interesting Solvent Area in Crystal Structures of Two Natural Ergot Alkaloids

The structures of ergotamine bis(benzene) solvate (1) and ergocristine bis(benzene) solvate (2) are reported. Both structures crystallise in theP212121space group with cell parameters:1,a= 14.2968(3) Å,b= 15.4700(2) Å,c= 17.8123(4) Å, andV= 3939.57(13) Å3;2,a= 11.8358(2) Å,b= 17.6469(3) Å,c= 19.7125(3) Å, andV= 4117.25(12) Å3. Unexpectedly, despite the chemical similarity, structures of1and2significantly differ not only in the unit cell parameters, but also in the packing. Whereas in1solvent cavities are separated, there is only one unusual continuous solvent area in2filled with benzene, forming independent three-dimensional structure.

1,1',3,3',6,6',8,8'-Octachloro-9,9'-bifluorenylidene and perchloro-9,9'-bifluorenylidene, two exceedingly twisted ethylenes

The syntheses of 1,1',3,3',6,6',8,8'-octachloro-9,9'-bifluorenylidene (1), its precursors, and the byproduct 3,3',5,5'-tetrachloro-4-(trichloromethyl)biphenyl (5) are described. Accurate structural X-ray data on 1 and on perchloro-9,9'-bifluorenylidene (2) are reported and discussed. Because of chlorine overcrowding, the dihedral angles between their two identical fluorenylidene moieties are abnormally large, the central-ethylene twist angles being 55 and 66 degrees, respectively. Significant out-of-plane carbon-chlorine bond bending is likewise exhibited. Their ESR spectra and magnetic measurements prove that they are singlet species. The exceptionally large bathochromic displacements of their UV-vis absorption spectrum with respect to that of their parent hydrocarbon are mainly attributed to bond bending and molecular warping.

Selective Reduction of Peptidic Ergot Alkaloids

Five 6'-deoxoergopeptines were prepared in 51-68% yield by selective reduction of parent alkaloids with lithium aluminium hydride in tetrahydrofuran at low temperature. New compounds were characterized by mass spectrometry and NMR spectroscopy. The conformation of the peptide part in starting compounds and reduced derivatives is discussed on the basis of crystal structure determination of 6'-deoxo-9,10-dihydroergotamine dihydrate butan-2-one solvate as a representative member of the series.

Struktur des Ergolinderivats 1,1-Diethyl-3-[(2R,3R,5R,8S,10S)-2,3-dihydro-2,6-dimethyl-8-ergolinyl]-harnstoff bei drei verschiedenen Temperaturen: 295 K, 50 K und 15 K

The structure of the ergoline derivative 1,1-Diethyl-3-[(2R,3R,5R,8S,10S)-2,3-dihydro-2,6-dimethyl-8-ergolinyl]-urea has been determined by X-ray single crystal diffraction at three temperatures: 295, 50 and 15 K. Large displacement parameters of the diethyl-urea side group atoms cause rather improper bond distances at room temperature which, after cooling, adopt normal values. An inspection of the displacement parameters expressed in U eq's, shows that even the temperature reduction from 50 to 15 K causes an average decrease of U eq's by 33%. At room temperature, the individual displacement parameters depend strongly on the atomic distances from the molecular center of gravity. This dependence disappears almost completely at 15 K.

The molecular structure of adrenergic and dopaminergic substances

At the end of the last century it was established that the different nerve cells along a neuronal path do not come into direct physical contact with one another, but that there are narrow gaps between them, called synapses (Sherrington, 1897; Ramón y Cajal, 1906). Elliot (1905) made the basic experimental observation that the propagation of nerve impulses across a synapse might be mediated by specific chemical agents (see Fig. i). Such substances are now called neurotransmitters, and some 20 different compounds putatively responsible for synaptic transmission in different parts of the nervous system are known at present, e.g. a few recently isolated polypeptides. The most extensively studied transmitters are acetylcholine and the catecholamine group, consisting of dopamine (a), noradrenaline (b), and adrenaline (c).