Regioselective Synthesis of Trichloromethyl‐Substituted Salicylates and Cyclohexenones by One‐Pot Cyclizations of 1,3‐Bis(trimethylsilyloxy)buta‐1,3‐dienes

A variety of 6‐(trichloromethyl)salicylates (=2‐hydroxy‐6‐(trichloromethyl)benzoates) were prepared by TiCl₄‐mediated cyclization of 1,3‐bis(trimethylsilyloxy)buta‐1,3‐dienes with 1,1,1‐trichloro‐4,4‐dimethoxybut‐3‐en‐2‐one. The employment of trimethylsilyl trifluoromethanesulfonate (Me₃SiOTf) as Lewis acid resulted in the formation of trichloromethyl‐substituted cyclohexenones. The cyclizations proceeded with good‐to‐very‐good regioselectivities.     

Dopant-modulated pair interaction in cuprate superconductors

A comparison of recent experimental STM data with single-impurity and many-impurity Bogoliubov-de Gennes calculations strongly suggests that random out-of-plane dopant atoms in cuprates modulate the pair interaction locally. This type of disorder is crucial to understanding the nanoscale electronic inhomogeneity observed in BSCCO-2212, and can reproduce observed correlations between the positions of impurity atoms and various aspects of the local density of states such as the gap magnitude and the height of the coherence peaks. Our results imply that each dopant atom modulates the pair interaction on a length scale of order one lattice constant.     

Nonrelativistic Quantum Mechanics with Fundamental Environment

Spontaneous transitions between bound states of an atomic system, “Lamb Shift” of energy levels and many other phenomena in real nonrelativistic quantum systems are connected within the influence of the quantum vacuum fluctuations (fundamental environment (FE)) which are impossible to consider in the limits of standard quantum-mechanical approaches. The joint system “quantum system (QS) + FE” is described in the framework of the stochastic differential equation (SDE) of Langevin-Schr?dinger (L-Sch) type, and is defined on the extended space R ³ ⊗ R _{ξ}, where R ³ and R _{ξ} are the Euclidean and functional spaces, respectively. The density matrix for single QS in FE is defined. The entropy of QS entangled with FE is defined and investigated in detail. It is proved that as a result of interaction of QS with environment there arise structures of various topologies which are a new quantum property of the system.     

Synthesis of 2‐Unsubstituted 1,3‐Selenazoles by Cyclization of Selenoformamide with α‐Bromocarbonyl Compounds

2‐Unsubstituted 1,3‐selenazoles were prepared by cyclization of selenoformamide with α‐bromoacetophenones. Parent 1,3‐selenazole was prepared by cyclization of selenoformamide with α‐bromoacetaldehyde.     

Unexpected Ring Enlargement of 2‐Hydrazono‐2,3‐dihydro‐1,3‐thiazoles to 1,3,4‐Thiadiazines

The cyclization of thiosemicarbazide with α‐bromoacetophenone can result in the formation of isomeric 1,3,4‐thiadiazines and two different thiazoles. We studied the use of 4‐methyl‐ and 4‐ethylthiosemicarbazide as dinucleophilic building blocks. In this context, we observed an unprecedented rearrangement of a 2‐hydrazono‐2,3‐dihydrothiazole to a 1,3,4‐thiadiazine. While ring contractions of 1,3,4‐thiadiazines to thiazoles are quite common, ring enlargements are new. The course of the reaction depends on the substitution pattern of the substrate.     

Cyclization of 4‐Phenylthiosemicarbazide with Phenacylbromide Revisited. Formation of 1,3,4‐Thiadiazines and of Isomeric 1,3‐Thiazoles

The cyclization of 4‐phenylthiosemicarbazide with phenacylbromide, carried out in refluxing ethanol, afforded 1,3,4‐thiadiazine 1 as the major product. In contrast to a previous report, 2‐phenylimino‐4‐phenyl‐2,3‐dihydro‐1,3‐thiazol‐3‐amine ( 2 ) and not 2‐hydrazono‐3,4‐diphenyl‐2,3‐dihydro‐1,3‐thiazole ( 8 ) was formed as a side‐product. This product is the main product when the reaction is carried out in concentrated hydrochloric acid. Our findings were independently confirmed by independent syntheses of the isomeric products and by a thorough study of their reactivity. It is important to note that the product distribution of the cyclization of thiosemicarbazides with haloketones strongly depends on the substitution pattern and on the reaction conditions.     

Andreev states near short-ranged pairing potential impurities

We study Andreev states near atomic scale modulations in the pairing potential in both s- and d-wave superconductors with short coherence lengths. For a moderate reduction of the local gap, the states exist only close to the gap edge. If one allows for local sign changes of the order parameter, however, resonances can occur at energies close to the Fermi level. The local density of states (LDOS) around such pairing potential defects strongly resembles the patterns observed by tunneling measurements around Zn impurities in Bi2Sr2CaCu2O8+x (BSCCO). We discuss how this phase impurity model of the Zn LDOS pattern can be distinguished from other proposals experimentally.     

Dissipative Evolution of the Qubit State in the Tomographic-Probability Representation

We consider the evolution of qubit states for the Demkov problem in the presence of dephasing processes in the spin tomographic-probability representation. We present an explicit solution of the spin tomogram in terms of the ₁ F ₂ hypergeometric function. We calculate the tomographic Shannon and q entropies through the solution of the master equation in the form of tomographic-probability distribution of the qubit states obtained.     

Cell-permeable near-infrared fluorogenic substrates for imaging beta-lactamase activity

This communication describes a design of cell-permeable near-infrared fluorogenic substrates for imaging beta-lactamase expression in living mammalian cells. This design is based on fluorescence energy transfer resonance and utilizes a peracetylated d-glucosamine to facilitate the transport of the near-infrared probe across cell membranes. This new type of fluorogenic probe may also be applied to image gene expression in living animals.