Results 1 - 10 of 4186
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[en] Information on the methods of synthesis of 4-aryl- or 4-hetaryl-substituted pyridines developed in the recent years is discussed and generalised. Examples of the practical use of 4-(het)arylpyridine derivatives are given.
[en] Data on furo[2,3-b]pyridines published in the last 15 years are integrated and analyzed for the first time. Information on the methods of synthesis, chemical transformations and biological action of these systems is described systematically. Particular attention is paid to the preparation and study of properties of polycondensed derivatives as the most promising and rapidly developing line of research of furo[2,3-b]pyridine chemistry. The biological properties of this class of compounds are discussed, and examples of furo[2,3-b]pyridines that exhibit high biological activities are given. The bibliography includes 88 references
[en] The reduction of molybdenum (VI) in 2,3-dihydroxypyridine, 2-amino-3-hydroxypyridine, 3-hydroxypyridine-2-thiol has been investigated (μ=0.1, supporting electrolyte-sodium perchlorate). Diffusion controlled irreversible cathodic waves are obtained. The values of kinetic parameters, αn and Ksub(f,h)sup(0) have been determined by applying the method of Oldham and Parry. (author)
[en] The kinetics and mechanism of the pyridinolysis (XC5H4N) of diethyl isothiocyanophosphate are investigated in acetonitrile at 55.0 .deg. C. The Hammett and Bronsted plots for substituent X variations in the nucleophiles exhibit the two discrete slopes with a break region between X = 3-Ac and 4-Ac. These are interpreted to indicate a mechanistic change at the break region from a concerted to a stepwise mechanism with rate-limiting expulsion of the isothiocyanate leaving group from a trigonal bipyramidal pentacoordinated intermediate. The relatively large βX values with more basic and less basic pyridines imply much greater fraction of frontside nucleophilic attack TSf than that of backside attack TSb
[en] The review surveys the state-of-the-art in the methodology of multicomponent cascade heterocyclisation and its prospects as applied to the targeted synthesis of polyfunctional pyridines and their hydrogenated and fused analogues.
[en] The nucleophilic substitution reactions of diisopropyl chlorothiophosphate with X-pyridines have been kinetically studied in MeCN at 35.0 .deg. C. The Hammett and Bronsted plots for the substituent X variations in the nucleophiles show biphasic concave upwards with a break point at X = 3-Ph. The pyridinolysis rate of 5 exhibits great negative deviation from the Taft plot. A concerted SN2 mechanism is proposed involving a change of the attacking direction of the X-pyridines from a frontside attack with the strongly basic pyridines to a backside attack with the weakly basic pyridines
[en] In the present work, catalytic activity of basic alumina in water has been demonstrated for the synthesis of poly functionalized pyridines. This strategy has some remarkable advantages, such as use of heterogeneous catalyst in aqueous media, reusability of catalyst and scalable approach