Extensive myelitis associated with anti-NMDA receptor antibodies.

International audienceBACKGROUND: Encephalitis with anti-N-methyl-D-aspartate receptor antibodies (anti-NMDAR-Ab) is a rapid-onset encephalitis including psychosis, seizures, various movement disorders and autonomic system disturbances. CASE PRESENTATION: We report a very unusual case of extensive myelitis associated with anti-NMDAR-Ab. MRI also revealed a hyperintense T2 lesion, non-suggestive of MS, which progressively extended, associated with periventricular gadolinium enhancement visualized on brain MRI. Ophthalmological evaluation showed subclinical right optic neuritis. The absence of anti-AQP4 antibody argued against neuromyelitis optica spectrum disorder. A slight psychomotor slowing prompted us to search for various causes of autoimmune encephalitis. Anti-NMDAR-Ab was found in cerebrospinal fluid. CONCLUSION: In patients with extensive myelitis who are seronegative for anti-AQP4 antibodies, and after other classical causes have been excluded, the hypothesis of atypical anti-NMDAR-Ab encephalitis should also be considered

Synthesis and Stereochemical Properties of Chiral Square Complexes of Iron(II)

Der hexadentate und ditopische Ligand 2,5-Bis([2,2']bipyridin-6-yl)pyrazin bildet bei der Selbstorganisationsreaktion mit Fe²⁺-Ionen einen chiralen, quadratförmigen Tetramerkomplex. Das Racemat dieses Komplexes wurde mit Hilfe von Antimonyltartrat in die Enantiomere getrennt. Die Reinheit des Enantiomers wurde durch NMR-Spektroskopie unter Zuhilfenahme eines chiralen, diamagnetischen Shift-Reagenzes untersucht, wie auch duch die Beobachtung des Circulardichroismus (CD). Das CD-Spektrum wurde zudem mit zeitabhängiger Dichtefunktionaltheorie berechnet, wobei die vorhergesagte Korrelation zwischen CD-Spektrum und Konfiguration des Komplexes durch Röntgenstrukturanalyse bestätigt wurde. Die Verwendung einer chiralisierten Variante des Liganden ergab den entsprechenden Eisenkomplex in diastereomerenreiner Form.The hexadentate, and ditopic ligand 2,5-bis([2,2']bipyridin-6-yl)pyrazine yields a chiral, tetrameric, square-shaped, self-assembled species upon complexation with Fe²⁺ ions. The racemate of this complex was resolved with antimonyl tatrate as the chiral auxiliary. The purity of the enantiomer was determined by NMR spectroscopy, by using a chiral, diamagnetic shift reagent, and by circular dichroism (CD). The CD spectrum was also calculated by time-dependent density functional theory, and the correlation that was found between CD spectrum and configuration was confirmed by X-ray cristallography. When a chiralised version of the ligand was used instead, the corresponding iron complex was obtained in diastereomerically pure form

Towards the stereoselective synthesis of inherently chiral pseudorotaxanes

Herein is reported an investigation towards the stereoselective synthesis of inherently chiral pseudorotaxanes. Chiral ammonium threads were readily prepared in five steps from racemic or enantiopure (M or P) salts of di-n-propyl-1,13-dimethoxyquinacridinium cation. Their self-assembly with DB24C8 or disymmetrically oriented DB24C8F6 rings formed pseudorotaxanes as shown by 1H and 19F NMR spectroscopy as well as MS measurements. A determination of the association constants (Ka) was afforded. The crucial role played by the ammonium counter-ion in the threading process was further demonstrated as salts of TRISPHAT (tris(tetrachlorobenzenediolato)phosphate(V)) anion were quite more effective than their PF6− analogues (× 7.3). A general lack of diastereoselectivity (de ≤ 8%) was unfortunately observed

Kinetic Control in the Chiral Recognition of Three-Bladed Propellers

The ion pair of the stereolabile C3-symmetric, i+o proton complex [1⋅H]+ of diaza-macropentacycle 1 and the configurationally stable Δ-TRISPHAT ([Δ-3]−) anion exists in the form of two diastereomers, namely, [Δ-(1⋅H)][Δ-3] and [Λ-(1⋅H)][Δ-3], the ratio of which, in terms of diastereomeric excess (de) decreases in the order [D8]THF (28 %)>CD2Cl2 (22 %)>CDCl3 (20 %)>[D8]toluene (16 %)>C6D6 (7 %)>[D6]acetone (0 %) at thermodynamic equilibrium. Except in the case of [D6]acetone, the latter is reached after a period of time that increases from 1 h ([D8]THF) to 24 h (CDCl3). Moreover, the initial value of the de of [1⋅H][Δ-3] in CDCl3, before the thermodynamic equilibrium is reached, depends on the solvent in which the sample has been previously equilibrated (sample “history”). This property has been used to show that the crystals of [1⋅H][Δ-3] formed by slow evaporation of CH2Cl2/CH3OH mixtures had 100 % de, which indicates that [1⋅H][Δ-3] has enjoyed a crystallization-induced asymmetric transformation. Structural studies in solution (NMR spectroscopy) and in the gas phase by calculations at the semiempirical PM6 level of theory suggest that the optically active anion is docked on the i+ (endo) external side of the proton complex such that one of the aromatic rings of [Δ-3]− is inserted into a groove of [1⋅H]+, a second aromatic ring being placed astride the outside i+ pocket. Solvent polarity controls the thermodynamics of inversion of the [1⋅H]+ propeller. However, both polarity and basicity control its kinetics. Therefore, the rate-limiting steps correspond to the ion-pair separation/recombination and [1⋅H]+/1 deprotonation/protonation processes, rather than the inversion of [1⋅H]+, the latter being likely to take place in the deprotonated form (1)