Ресурсный центр «Магнитно-резонансные методы исследования»

Сигнал ЯМР на современных приборах лежит в радиочастотном диапазоне. Однако при оцифровке из сигнала вычитается опорная частота, и в результате получается сигнал с частотой, которую мог бы услышать человек. Например, если мы снимаем протонный спектр на приборе с постоянным полем 300 МГц, типичный интервал для сигналов порядка 3 кГц, при этом обычный человек способен слышать звук от 16 Гц до 20 кГц.

При проведении эксперимента по ЯМР первичным результатом является получение спада свободной индукции, который может быть преобразован в аудиофайл, например, при помощи NMR-Talk от Боба Хэнсона из колледжа св. Олафа.

A.S. Pankova, A.Yu. Stukalov, M.A. Kuznetsov

“Synthesis of 2‑(Hetero)aryl-5-(trimethylsilylethynyl)oxazoles from 2 (Hetero)arylacrylic Acids”

Org. Lett., 2015, accepted

DOI:10.1021/acs.orglett.5b00009

A three-step method for the synthesis of 2-(hetero)-aryl-5-(trimethylsilylethynyl)oxazoles is described. Easily accessible bis(trimethylsilyl)acetylene and acrylic acid derivatives are used as starting materials for the preparation of mono- and disubstituted 5-(trimethylsilyl)pent-1-en-4-yn-3-ones. Oxidative phthalimido-aziridination of these enynones provides the key 2-acyl-1-phthalimido-aziridines that are further utilized in the thermal expansion of the three-membered ring to furnish the target functionalizable oxazoles.

P.R. Golubev, A.S. Pankova, M.A. Kuznetsov

“Regioselective Transition-Metal-Free Synthesis of 2‑(Trimethylsilylmethylene)pyrrol-3-ones by Thermal Cyclization of Acetylenic Enamines”

J. Org. Chem., 2015, accepted

DOI:10.1021/acs.joc.5b00398

Acetylenic enamines generated in situ from readily available enynones and primary amines undergo thermal cyclization in diphenyl ether providing easy access to 4-aryl-2-(trimethylsilylmethylene)-1,2-dihydro-3H-pyrrol-3-ones. This reaction is inherently versatile, allowing for variations of substituents in both enynone and amine. Full regioselectivity along with short reaction time (1−2 h) and simple workup afford single products in good to excellent isolated yields. Fluorescent properties of the obtained compounds were studied.>

S.N. Britvin, A. Lotnyk

“Water-Soluble Phosphine Capable of Dissolving Elemental Gold: The Missing Link between 1,3,5-Triaza-7-phosphaadamantane (PTA) and Verkade’s Ephemeral Ligand”

J. Am. Chem. Soc., 2015, accepted

DOI:10.1021/jacs.5b01851

We herein describe a tricyclic phosphine with previously unreported tris(homoadamantane) cage architecture. That water-soluble, air- and thermally stable ligand, 1,4,7-triaza-9-phosphatricyclo[5.3.2.14,9]tridecane (hereinafter referred to as CAP) exhibits unusual chemical behavior toward gold and gold compounds: it readily reduces Au(III) to Au(0), promotes oxidative dissolution of nanocrystalline gold(0) with the formation of water-soluble trigonal CAP−Au(I) complexes, and displaces cyanide from [Au(CN)2]− affording triangular [Au(CAP)3]+ cation. From the stereochemical point of view, CAP can be regarded as an intermediate between 1,3,5-triaza-7-phosphaadamantane (PTA) and very unstable aminophosphine synthesized by Verkade’s group: exahydro-2a,4a,6a-triaza-6bphosphacyclopenta[cd]pentalene. The chemical properties of CAP are likely related to its anomalous stereoelectronic profile: combination of strong electron-donating power (Tolman’s electronic parameter 2056.8 cm−1) with the low steric demand (coneangle of 109°). CAP can be considered as macrocyclic counterpart of PTA with the electron-donating power approaching that of strongest known phosphine electron donors such as P(t-Bu)3 and PCy3. Therefore, CAP as sterically undemanding and electronrich ligand populates the empty field on the stereoelectronic map of phosphine ligands: the niche between the classic tertiary phosphines and the sterically undemanding aminophosphines.

A.P. Molchanov, Yu.V. Malinina, R.R. Kostikov, A.V. Stepakov

“Regioselective Cycloaddition of C,N-Diarylnitrones to Arylallenes and of N-Aryl-C-carbamoylnitrones to Methyl Buta-2,3-dienoate”

Russ. J. Org. Chem, 2015, 51, 368-372

DOI:10.1134/S1070428015030136

Cycloadditions of C,N-diarylnitrones to non-activated arylallenes and of N-aryl-C-carbamoylnitrones to methyl buta-2,3-dienoate regioselectively afforded mixtures of diastereoisomeric substituted 4-methylideneisoxazolidines.

A.V. Stepakov, A.G. Larina, A.P. Molchanov

“Isomerization of Dimethylenecyclopropanes in Benzofulvenes in the Presence of Lewis Acids”

Russ. J. Org. Chem, 2015, 51, 210-213

DOI:10.1134/S1070428015020128

1,1-Diaryl-2-(1-methylethylidene)-3-methylenecyclopropanes in the presence of Lewis acid isomerize in benzofulvene derivatives.