Aza-Diels–Alder reaction catalyzed by novel chiral metalocomplex Brønsted acids

A series of Co(III) anionic complexes of Schiff bases obtained from salicylaldehydes and enantiomerically pure amino acids has been synthesized. The outersphere counterion was exchanged by H⁺ and the novel chiral Brønsted acids were used to induce asymmetry into an aza-Diels–Alder reaction. The influence of the temperature, solvent polarity, and structural modification of the chiral anions on the enantioselectivity of the process has also been investigated.     

Synthesis of heteroannulated 3-nitro- and 3-aminopyridines by cyclocondensation of electron-rich aminoheterocycles with 3-nitrochromone

3-Nitrochromone reacts with electron-rich aminoheterocycles (in glacial acetic acid at reflux) and anilines (in a mixture of DMF and TMSCl at 100–140 °C) to give a variety of hetero(carbo)annulated 3-nitropyridines. The reaction, involving a formal [3+3] cyclocondensation, proceeds in high yields and appears not to be influences greatly by the nature of the 1,3-C,N-dinucleophile as seen from the thorough scope study. The synthetic utility of the products was demonstrated by their conversion into the corresponding 3-aminopyridine derivatives. An NMR study and X-ray crystallographic analysis are reported.     

Spatial modulation of X-rays in the presence of external acoustic field

The two-crystal X-ray diffraction from (111?1) reflecting atomic planes of quartz single crystal with AT-cut was experimentally considered in the Laue geometry, when both the crystals are simultaneously in the field of bulk acoustic waves. It is shown that as a result of spatial modulation of reflected beam an odd number of parallel X-ray beams is obtained.     

On generating functions of higher-spin cubic interactions

We present off-shell generating functions for all cubic interactions of totally symmetric massless Higher-Spin gauge fields and discuss their properties.     

Feature of kinematic diffraction of nonmonochromatic divergent X-ray beams in a crystal with a periodically strained lattice

Coherent scattering of a nonmonochromatic divergent beam of X-ray quanta in a crystal excited by an acoustic wave is described using a kinematic approach. The possibility of manifestation of a peculiar effect of amplification of the diffracted X-ray beam by the acoustic wave is predicted using this approach.     

Intramolecular Cycloaddition of [3-(Naphthalen-1-yl)prop-2-yn-1-yl](3-phenylprop-2-en-1-yl)ammonium Bromides and Cleavage of Some of the Obtained Cyclic Salts in Aqueous Alkali

Russian Journal of Organic Chemistry - Intramolecular cycloaddition of [3-(naphthalen-1-yl)prop-2-yn-1-yl](3-phenylprop-2-en-1-yl)ammonium bromide under very mild conditions afforded potentially...     

Characterization of bismuth germanate crystals grown by EFG method

Bismuth germanate shaped crystals have been grown by the EFG (Stepanov) method. The correlation between growth rate, shape of crystals, their optical and scintillation parameters has been analysed. Optical and scintillation characteristics of the EFG crystals are similar to those obtained with Czochralski grown crystals, however, growth rate in EFG is by 2.5 times larger. Also we compare the photochromic effect under UV‐irradiation in EFG and Czochralski grown crystals. Material losses at fabrication of plates, pixels, and rods from EFG shaped plates may be reduced by ∼50% compared to large diameter boules.     

Generalized wave polynomials and transmutations related to perturbed Bessel equations

The transmutation (transformation) operator associated with the perturbed Bessel equation is considered. It is shown that its integral kernel can be uniformly approximated by linear combinations of constructed here generalized wave polynomials, solutions of a singular hyperbolic partial differential equation arising in relation with the transmutation kernel. As a corollary of this result an approximation of the regular solution of the perturbed Bessel equation is proposed with corresponding estimates independent of the spectral parameter.     

Derivatives of Condensed Thieno[2,3-d]pyrimidines. 15. Synthesis of 2-Substituted 3-Amino-6,6-dimethyl-5,6-dihydro-8H-pyrano[4'3':4,5]thieno[2,3-d]pyrimidin-4-ones

A method has been developed for the preparation of 2-R-substituted 3-amino-6,6-dimethyl-5,6-dihydro-8H-pyrano[4'3':4,5]thieno[2,3-d]pyrimidin-4-ones based on 2-R-amino-3-ethoxycarbonylpyrano[2,3-c]thiophenes. It has been established that their cyclization with hydrazine hydrate requires vigorous conditions.