Ring transformations of β-lactam-condensed 1,3-benzothiazines to isoquinoline and thiazole derivatives by sulfur extrusion and addition sequences

The ring transformations of dichloro-β-lactam-fused 2-aryl-1,3-benzothiazines with sodium methoxide were investigated. With 2 equiv of base, the dichloro-β-lactam derivatives underwent rearrangement and dihydro-1,4-benzothiazepines, 3,4-substituted isoquinolines and substituted thiazole disulfides were isolated. A possible reaction mechanism is proposed for the simultaneous formation of the novel products. The formation of isoquinoline and thiazole derivatives can be explained by sulfur extrusion and addition sequences.     

Transformations on Density Operators That Leave the Holevo Bound Invariant

For a given probability distribution λ ₁,…,λ _m we determine the structure of all such maps defined on a dense subset of density operators which leave the Holevo bound invariant i.e. which satisfy $$S\Biggl(\sum_{k=1}^m \lambda_k \phi(\rho_k)\Biggr)- \sum_{k=1}^m \lambda_k S\bigl(\phi (\rho_k)\bigr)= S\Biggl(\sum _{k=1}^m \lambda_k \rho_k\Biggr)- \sum_{k=1}^m \lambda_k S(\rho_k) $$ for all possible collections ρ ₁,…,ρ _m of density operators.     

Preparation of Nitriles by the Modification of Mitsunobu-Wilk Procedure III Carbon Elongation of Hydroxy Esters

An efficient one-step procedure for the conversion of hydroxy esters into the corresponding nitrile esters using triphenylphosphine (PPh₃)-diethyl azodicarboxylate (DEAD) in the presence of acetone cyanohydrin is described.     

Elusive properties of infinite graphs

A graph property is said to be elusive (or evasive) if every algorithm testing this property by asking questions of the form “is there an edge between vertices $x$ and $y$?” requires, in the worst case, to ask about all pairs of vertices. The unsettled Aanderaa–Karp–Rosenberg conjecture is that every nontrivial monotone graph property is elusive for any finite vertex set. We show that the situation is completely different for infinite vertex sets: the monotone graph properties “every vertex has degree at least $n$” and “every connected component has size at least $m$,” where $n\ge 1$ and $m\ge 2$ are natural numbers, are not elusive for infinite vertex sets, but the monotone graph property “the graph contains a cycle” is elusive for arbitrary vertex set. On the other hand, we also prove that every algorithm testing some natural monotone graph properties, for example, “every vertex has degree at least $n$” or “connected” on the vertex set $\omega$ should check “lots of edges,” more precisely, all the edges of an infinite complete subgraph.     

Relationships between the stability,circular dichroism spectrum and type of substitution in inclusion complexes formed between phenophthalein and different cyclodextrins

The perturbation of the three-site interaction of phenolphthalein on complexation with different cyclodextrins (CDs) has been investigated as a function of the type and degree of substitution of the CD. The UV visible spectra are practically identical, while the circular dichroism spectra change dramatically both in intensities and signs. Parallel to this, the stability constants are influenced not only by the size of the cavity but also by the substitution of its rims, particularly by that of the primary hydroxyls. The two phenomena can be related to allow conclusions concerning the mode of inclusion.     

Elementary Operators on Standard Operator Algebras

We present a new simple proof of the structural result for elementary operators on standard operator algebras. Using the idea of this short proof we can characterize surjective maps between standard operator algebras having a certain multiplicativity-like property appearing in the abstract definition of elementary operators of length one. In particular, we show that such maps are automatically additive.     

The role of cyclodextrins in chiral capillary electrophoresis

The members of the enantiomeric pairs frequently show rather different biological effects, so their chiral selective synthesis, pharmacological studies and analysis are necessary. CE has unique advantages in chiral analysis. The most frequently used chiral selectors are CDs in this field. This paper gives a short view on the advantages on CE in direct chiral separations, emphasizing the role of CDs. The reason for the broad selectivity spectra of CDs is discussed in detail. The physical background of chiral selective separations is briefly shown in CE. Their interaction mechanisms are shortly defined. The general trend of their use is statistically evaluated. Most frequently used CDs and CD derivatives are characterized. Advantages of ionizable CDs and single-isomer derivatives are shown. The general trend of their use is established.     

Novel β-lactam condensed 3-thiaquinolines: an efficient synthesis and structural characterization

Quinoline analog 2-aryl-4H-3,1-benzothiazine derivatives 8-13, obtained by the condensation of o-aminobenzyl chloride 1 with substituted thiobenzamides 2-7, were transformed to azeto[2,1-a][3,1]benzothiazin-1-one derivatives 18-23a,b,c and 24d,e by reaction with the corresponding substituted acetyl chlorides 14-17 in the presence of triethylamine. The structures of the new molecules were determined by NMR spectroscopy and electron ionization (EI) mass spectrometry. The typical EI⁺ mass spectrometric fragmentations of 8-13 and 18-23a,b,c and 24d,e are discussed in detail.     

Palladium-catalyzed amination of quinaldine-5-triflate

Palladium-catalyzed amination reactions of quinoline triflate and the effect of a Pd catalyst, its ligands, solvents, bases, and temperature were studied. This method facilitated an easier pathway for the preparation of aminoquinoline derivatives as potential precursors of new serotoninerg agents.