C–F Bond Cleavage Reactions with Beryllium,Magnesium, Gallium,Hafnium, and Thorium Halides

The work describes unexpected stoichiometric C–F bond cleavage reactions of beryllium, magnesium, gallium, hafnium and thorium halides with α,α,α-trifluorotoluene. The reaction of BeBr₂ / GaBr₃ or MgBr₂ / GaBr₃ mixtures as well as neat GaI₃ with α,α,α-trifluorotoluene in the presence of (OSi₂Me₄)₂ ( I ) yields the carbenium ion containing compounds [Ph-C(O₂Si₂Me₄)][GaX₄] (X = Br: 1 , X = I/F: 2 ). Both compounds were successfully characterized and a defluorination type reaction under incorporation of a siloxy unit was observed. Compound 1 was also characterized by single-crystal X-ray diffraction analysis. The conversion of α,α,α-trifluorotoluene with BeI₂, HfI₄ or ThI₄ turned out to be a halodefluorination-type reaction with formation of α,α,α-triiodotoluene ( 3 ). An adequate NMR spectroscopic and the X-ray crystallographic characterization of 3 were performed for the first time.     

Atropisomers of meso Tetra(N-Mesyl Pyrrol-2-yl) Porphyrins: Synthesis,Isolation and Characterization of All-Pyrrolic Porphyrins

Atropisomerism has been observed in a variety of biaryl compounds and meso-aryl substituted porphyrins. However, in porphyrins, this phenomenon had been shown only with o-substituted 6-membered aromatic groups at the meso-position. We show herein that a 5-membered heteroaromatic (N-mesyl-pyrrol-2-yl) group at the meso-position leads to atropisomerism. In addition, we report a ‘one-pot’ synthetic route for the synthesis of ‘all-pyrrolic’ porphyrin (APP) with several N-protection groups (Boc, Cbz, Ms and Ts). Among these groups, we found that only the Ms group gave four individually separable atropisomers of meso-tetra(N-Ms-pyrrol-2-yl) porphyrin. Furthermore, the reductive removal of Cbz- was achieved to obtain meso-tetra(pyrrol-2-yl) porphyrin. Thus, our synthetic procedure provides an easy access to a group of APPs and stable atropisomers, which is expected to expand the application of novel APP-based materials.     

Use of a small particle solid‐core packing for improved efficiency and rapid measurement of sirolimus and everolimus by LC‐MS/MS

Measurement of whole blood sirolimus and everolimus is required in order to optimize patient treatment following solid organ transplant. Assay by LC‐MS/MS is increasingly preferred; however efficient use of the instrument and short turnaround times are crucial. Use of a 1.6 µm solid‐core packing HPLC column (Cortecs) gave significant increases in efficiency, sensitivity and throughput compared with an existing method, following simple protein precipitation of small‐volume (20 μL) whole blood samples. Sirolimus, everolimus and the stable isotopic internal standard (¹³C₂D₄ – everolimus) eluted at around 0.8 min, and total analytical run time was 2.2 min, saving almost 4 min per sample compared with an existing method. Within‐assay imprecision (CV) was 3.3–8.5%, and between‐assay imprecision was 2.2–10.8%. Retrospective assay of external quality assurance samples and comparison of patient samples assayed in parallel showed only small differences (between +6.8 and ?1.9%) in results using the Cortecs column when compared with the existing method. No significant interferences or ion suppression were observed. Copyright © 2015 John Wiley & Sons, Ltd.     

(E,E,E)‐1,3,5‐Tris[4‐(acetyl­sulfan­yl)­styr­yl]­benzene toluene hemisolvate

The first crystal structure of a three‐terminal sulfur end‐capped oligo­phenyl­ene­vinyl­ene, C₃₆H₃₀O₃S₃·0.5C₇H₈, has been determined at 122 (1) K. The mol­ecular threefold symmetry is not utilized in the crystal structure. It is confirmed that the double bonds have been fully transformed into a trans configuration by iodine treatment.     

One-pot three-component reaction for the synthesis of alpha-(aminoethyl)-alpha,beta-enones

[reaction: see text] The synthesis of alpha-substituted alpha,beta-enones by a new metal iodide-promoted one-pot three-component reaction involving commercially available cyclopropyl ketones, aldehydes, and secondary amines followed by base treatment is described.     

Aktive Kreiselsysteme

übersicht Aktive Elemente in Kreiselsystemen k?nnen sich in verschiedenartigen Effekten auswirken. Allgemeine Bewegungsgleichungen werden abgeleitet. Mit ihrer Hilfe lassen sich globale Aussagen zum Stabilit?tsverhalten von Kreiselsystemen mit Rotorantrieb gewinnen: 1) Konservative Systeme bleiben auch dann quasi-konservativ, wenn eine ideal wirkende Antriebsregelung vorhanden ist, die die relativen Geschwindigkeiten zwischen den Rotoren und ihren Geh?usen konstant h?lt. 2) Eigenstabile Asynchron-Antriebe machen ein grenzstabiles Kreiselsystem asymptotisch stabil bezüglich der Geschwindigkeiten. 3) Entsprechendes gilt für eigenged?mpfte Synchron-Antriebe; hier gilt die asymptotische Stabilit?t auch für die Rotorwinkel selbst. Am Beispiel einer motorangetriebenen Zentrifuge werden diese Ergebnisse durch Untersuchen der Eigenwerte pr?zisiert. Zugleich wird gezeigt, da? bezüglich der Lagewinkel Instabilit?t infolge kinetischer Auswanderung auftreten kann.

---

Summary Due to active elements in gyroscopic systems various effects may occur. For their examination quite general equations of motion are derived, which allow some globale statements concerning the stability of gyro-systems with motor-driven rotors: 1) Conservative systems will behave quasi-conservative, if ideal working controllers are installed, which keep the relative rotational velocities of the rotors constant. 2) Asynchronous driving motors, which are stable for themselves, turn a marginal stable system into a system, asymptotically stable with respect to the velocities. 3) The same is valid for systems, in which the rotors are driven by damped synchronous motors; here asymptotic stability exists for the rotor-angles as well. As an example a motor-driven centrifuge is examined. The general results are proved and extended by calculating the eigenvalues. Furthermore it is shown that unstable behaviour with respect to the attitude angles is possible due to effects of kinetic drift.

---

---

Hans Ziegler zum 70. Geburtstag gewidmet     

Hyperpolarization of 13C through order transfer from parahydrogen: a new contrast agent for MRI

The order within proton pairs in organic molecules, resulting from hydrogenation with parahydrogen, can be transferred in great part to nearby carbon 13 spins through adequate field manipulations. The molecules with hyperpolarized 13C thus obtained can be used as new contrast agents of high efficiency in MRI. After a brief presentation of the hydrogenation process and apparatus, in relatively low magnetic field, we describe the procedure of order transfer to the 13C spins through a sudden drop from the initial field to zero field followed by an adiabatic remagnetization. The expected final polarizations in the absence of relaxation are given for several compounds. Finally, we show an example of MR images observed in vivo on animals as an illustration of the contrast capacity of this new method.     

A novel oxidative rearrangement of 6-methoxypyran-2-ones

As part of our continuing studies of pyrone-containing natural products, a series 6-methoxypyran-2-ones were synthesized. These were found to react with molecular oxygen at 20 degrees C, and this novel reaction yielded a series of highly functionalized alpha,beta-butenolides. [reaction: see text]