213 research outputs found
PREPARATION A SERIES OF ATROPISOMERIC BIPY-DIOXIDES BY OXIDATIVE COUPLING AND THEIR APPLICATION IN ASYMMETRIC CATALYSIS
The authors thank the Russian Science Foundation for Grant No. 18-73-10156
Thermodynamics of Large AdS Black Holes
We consider leading order quantum corrections to the geometry of large AdS
black holes in a spherical reduction of four-dimensional Einstein gravity with
negative cosmological constant. The Hawking temperature grows without bound
with increasing black hole mass, yet the semiclassical back-reaction on the
geometry is relatively mild, indicating that observers in free fall outside a
large AdS black hole never see thermal radiation at the Hawking temperature.
The positive specific heat of large AdS black holes is a statement about the
dual gauge theory rather than an observable property on the gravity side.
Implications for string thermodynamics with an AdS infrared regulator are
briefly discussed.Comment: 17 pages, 1 figure, v2. added reference
OPTIMIZATION OF CATALYST STRUCTURE FOR ASYMMETRIC ALLYLATION-TYPE REACTIONS OF FUNCTIONALIZED TRICHLOROSILANES WITH AROMATIC ALDEHYDES
The authors thank the Russian Science Foundation for Grant 18-73-10156-П
Dehydration of Amides to Nitriles
The authors thank Russian Science Foundation for grant № 18-73-10156
Dehydration of amides to nitriles under conditions of a catalytic appel reaction
A highly expedient protocol for a catalytic Appel-type dehydration of amides to nitriles has been developed that employs oxalyl chloride and triethylamine along with triphenylphosphine oxide as a catalyst. The reactions are usually complete in less than 10 min with only a 1 mol % catalyst loading. The reaction scope includes aromatic, heteroaromatic, and aliphatic amides, including derivatives of α-hydroxy and α-amino acids
Asymmetric Propargylation of Aldehydes Catalyzed by New Chiral Lewis Bases
The authors thank the Russian Science Foundation for Grant № 18-73-10156
Stereoselective Synthesis of Atropisomeric Bipyridine N,N′-Dioxides by Oxidative Coupling
Bipyridine N,N′-dioxide is a structural fragment found in many bioactive compounds. Furthermore, chiral analogues secured their place as powerful Lewis base catalysts. The scope of the existing methods for the synthesis of atropisomeric bipyridine N,N′-dioxides is limited. Herein, we present a practical, highly chemo- and stereoselective method for oxidative dimerization of chiral pyridine N-oxides using O2 as a terminal oxidant. A series of 13 axially chiral bipyridine N,N′-dioxides were synthesized in up to 75% yield. © 2019 American Chemical Society
New Axially Chiral Bipyridines and Their Application in Asymmetric Catalysis for Total Synthesis
The authors thank the Russian Science Foundation for Grant 18-73-10156
Enantioselective propargylation of aldehydes catalyzed by new chiral Lewis bases
In this work we’ve designed a series of new chiral Lewis Bases and show their excellent catalytic ability in the reaction of asymmetric propargylation of aromatic and α-unsaturated aldehydes.The authors thank the Russian Science Foundation for Grant 18-73-10156
Electronic energy band parameters of CuInSe2 : Landau levels in magnetotransmission spectra
Magnetotransmission (MT) at magnetic fields up to 29 T was used to study the electronic structure of CuInSe2 in thin polycrystalline films. The zero field absorption spectra exhibited resolved A, B, and C free excitons. Quantum oscillations, due to diamagnetic excitons comprising electrons and holes from Landau levels quantized in the conduction and valence band, respectively, appeared in the MT spectra at fields over 5 T. Spectral energies of Landau levels and binding energies of the corresponding diamagnetic excitons, theoretically calculated assuming a quasicubic approximation of the CuInSe2 tetragonal lattice structure, helped to identify the character of the experimentally observed diamagnetic excitons. Spectral energies of diamagnetic excitons in the MT spectra with different circular polarizations were used to determine the electron and light hole effective masses, whereas heavy hole masses as well as the γ and γ1 Luttinger parameters, Ep Kane energy, and F parameter of the influence of remote bands, as well as their polaron values, were calculated using the Luttinger theory
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