An efficient computational model to predict the synthetic utility of heterocyclic arynes

Think before you act: a computational approach is reported for evaluating the synthetic potential of heterocyclic arynes. Routine and rapid calculations of arene dehydrogenation energies and aryne angle distortion predict the likelihood that a given hetaryne can be generated, as well as the degree of regioselectivity expected in a reaction between a given hetaryne and a nucleophilic trapping agent.     

Sulfonate pseudohalides of boron subphthalocyanine

The crystal structures of three sulfonate pseudohalide derivatives of boron subphthalocyanine (BsubPc) are described and compared with four structures of three published sulfonate derivatives. Benzenesulfonate boron subphthalocyanine [(benzenesulfonato)(subphthalocyaninato)boron, C₃₀H₁₇BN₆O₃S, (I)] crystallizes in the space group P with Z = 2. The structure contains two centrosymmetric π‐stacking interactions between the concave faces of the isoindoline units in the BsubPc ligands. 3‐Nitrobenzenesulfonate boron subphthalocyanine [(3‐nitrobenzenesulfonato)(subphthalocyaninato)boron, C₃₀H₁₆BN₇O₅S, (II)] crystallizes in the space group P2₁/c with Z = 4. The structure contains an intermolecular S—O...π interaction from the sulfonate group to a five‐membered N‐containing ring of an isoindoline unit on the concave side of a neighbouring BsubPc ligand, at a distance of 3.151 (3) Å. The crystal of methanesulfonate boron subphthalocyanine [(methanesulfonato)(subphthalocyaninato)boron, C₂₅H₁₅BN₆O₃S, (III)] was produced via sublimation and it is not a solvate, in contrast with two previously published structures of the same compound. Compound (III) crystallizes in the space group P2₁/n with Z = 2, and its structure is similar to that of the more common compound Cl‐BsubPc.     

Hydrogen‐Bond‐Enabled Dynamic Kinetic Resolution of Axially Chiral Amides Mediated by a Chiral Counterion

Non‐biaryl atropisomers are valuable in medicine, materials, and catalysis, but their enantioselective synthesis remains a challenge. Herein, a counterion‐mediated O‐alkylation method for the generation of atropisomeric amides with an er up to 99:1 is outlined. This dynamic kinetic resolution is enabled by the observation that the rate of racemization of atropisomeric naphthamides is significantly increased by the presence of an intramolecular O?H???NCO hydrogen bond. Upon O‐alkylation of the H‐bond donor, the barrier to rotation is significantly increased. Quantum calculations demonstrate that the intramolecular H‐bond reduces the rotational barrier about the aryl–amide bond, stabilizing the planar transition state for racemization by approximately 40 kJ mol^?1, thereby facilitating the observed dynamic kinetic resolution.     

Use of trimethylsilyl and other homologous trialkylsilyl derivatives for the separation and characterization of mono- and dihydroxycannabinoids by combined gas chromatography and mass spectrometry.

A gas chromatographic separation of dihydroxy- from monohydroxycannabinoids by the use of homologous trialkylsilyl derivatives is discussed. Trimethylsilyl derivatives produced a group of peaks containing both sets of compounds, sometimes poorly resolved, whereas by increasing the alkyl chain length to n-butyl complete fractionation into two groups, was achieved. The mass spectra of these derivatives resembled those of the trimethylsilyl derivatives with the addition of a set of ions resulting from estimation of the Si-alkyl chains as olefins.     

The preparation,characterisation and thermal analysis studies on complexes of cobalt(II), nickel(II), and copper(II) with 3-picolylamine

Some complexes of the thiocyanates, chlorides and bromides of cobalt(II), nickel(II) and copper(II) with 3-picolylamine have been prepared. The stereochemical configurations of the complexes were deduced using spectral and magnetic properties. The decomposition of the complexes was studied by thermogravimetry and differential thermal analysis.

---

Zusammenfassung Einige Komplexe der Thiocyanate, Chloride und Bromide von Kobalt(II) und Kupfer(II) mit 3-Picolylamin wurden hergestellt. Die stereochemischen Konfigurationen der Komplexe wurden aus den spektralen und magnetischen Eigenschaften abgeleitet. Die Zersetzung der Komplexe wurde thermogravimetrisch und differentialthermoanalytisch untersucht.

---

, , 3-. . .

     

Hadronic shifts

Shifts δ_H in hadronic levels are produced by coupling to real or virtual decay channels. Using the P-matrix formalism, a simple approximate expression for δ_H is obtained. An application is made to the Δ-multiplet.     

Multiparticle shadow effects on elastic scattering in the dual model

Unitarity effects of multiparticle channels on elastic scattering are studied schematically in the dual model. Explanations are offered for (A) the difference in energy dependence between ‘Pomeron’ and isospin exchanges, (B) the difference in the slopes of diffraction peaks for exotic and non exotic reactions, and (C) the ‘cross-over’ phenomenon.