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Добірка наукової літератури з теми "Oxazolidinas"

Автор: Grafiati

Опубліковано: 4 червня 2021

Оновлено: 1 лютого 2022

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Статті в журналах з теми "Oxazolidinas"

Couture, Philippe, та John Warkentin. "Spiro-fused 2-alkoxy-2-amino-Δ3-1,3,4-oxadiazolines. Synthesis and thermolysis to corresponding aminooxycarbenes". Canadian Journal of Chemistry 75, № 9 (1997): 1264–80. http://dx.doi.org/10.1139/v97-153.

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Анотація:

Δ3-1,3,4-Oxadiazolines spiro-fused at C2 to C2 to oxazolidines (12) or to C2 of tetrahydro-1,3-oxazines (13) were synthesized. The oxadiazolines undergo thermolysis in benzene at 90 °C with first-order rate constants of (1.6–50) × 10−5 s−1. The dependence of these rate constants on the nature of the substituents present on the oxadiazoline ring is consistent with a mechanism involving a carbonyl ylide intermediate. Substituents on N of the oxazolidine or tetrahydro-1,3-oxazine moieties play a major role in determining the fragmentation pathways. Oxadiazolines with N-carbonyl groups (12c–j, 13d,e) afford essentially quantitative yields of the corresponding aminooxycarbenes, while other fragmentation reactions compete with carbene generation in the case of oxadiazolines with N-methyl (12b, 13c) or N-sulfonyl (12k) groups. Keywords: nucleophilic carbene, aminooxycarbene, oxadiazoline, oxazolidin-2-ylidene, carbonyl ylide.

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Bajtel, Ákos, Mounir Raji, Matti Haukka, Ferenc Fülöp, and Zsolt Szakonyi. "Stereoselective synthesis and transformation of pinane-based 2-amino-1,3-diols." Beilstein Journal of Organic Chemistry 17 (May 3, 2021): 983–90. http://dx.doi.org/10.3762/bjoc.17.80.

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A library of pinane-based 2-amino-1,3-diols was synthesised in a stereoselective manner. Isopinocarveol prepared from (−)-α-pinene was converted into condensed oxazolidin-2-one in two steps by carbamate formation followed by a stereoselective aminohydroxylation process. The relative stereochemistry of the pinane-fused oxazolidin-2-one was determined by 2D NMR and X-ray spectroscopic techniques. The regioisomeric spiro-oxazolidin-2-one was prepared in a similar way starting from the commercially available (1R)-(−)-myrtenol (10). The reduction or alkaline hydrolysis of the oxazolidines, followed by reductive alkylation resulted in primary and secondary 2-amino-1,3-diols, which underwent a regioselective ring closure with formaldehyde or benzaldehyde delivering pinane-condensed oxazolidines. During the preparation of 2-phenyliminooxazolidine, an interesting ring–ring tautomerism was observed in CDCl3.

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Aldmairi, Abdul, David Knight, and Thomas Wirth. "Acid-Catalyzed Tandem Process for the One-Pot Synthesis of Oxazolidines." Synlett 28, no. 20 (2017): 2976–78. http://dx.doi.org/10.1055/s-0036-1591513.

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A simple protocol for the synthesis of oxazolidines from aziridines and allylic alcohols is reported. The solid-supported sulfonic acid catalyst can be easily removed after the reaction by a simple filtration leading to the oxazolidine reaction products in good to excellent yields.

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Dettwiler, James E., Laurent Bélec та William D. Lubell. "Synthesis and application of L-N-Boc-N-methyl-β-hydroxyvaline in the preparation of a depsipeptide". Canadian Journal of Chemistry 83, № 6-7 (2005): 793–800. http://dx.doi.org/10.1139/v05-033.

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Enantiopure (>99% ee) L-N-tert-butyloxycarbonyl-N-methyl-β-hydroxyvaline (2) was synthesized in six steps and 43% overall yield from D-serine methyl ester (5). Methyl (4S)-N-(9-phenylfluoren-9-yl)-oxazolidine-4-carboxylate (7) was prepared in two steps and 73% yield by N-phenylfluorenation of 5 followed by cyclization of N-(PhF)amino alcohol 6 with formaldehyde and catalytic p-toluenesulfonic acid (PhF = 9-phenylfluoren-9-yl). The addition of MeLi to oxazolidine carboxylate 7 produced the tertiary alcohol 8 in 91% yield. Oxazolidines 8 equilibrated with oxazolidine 9 under acidic conditions. Reduction of pure 8 or the mixture of oxazolidines 8 and 9 with NaCNBH3 and hydrochloric acid in anhydrous dioxane afforded N-methyl amino diol 11 in 86%92% yields. Attempts to selectively oxidize N-(PhF)amino diol 11 were unsuccessful; however, hydrogenation of 11 in the presence of di-tert-butyl dicarbonate gave the corresponding N-(Boc)amino diol 12 in 82% yield. Selective oxidation of diol 12 was performed using a cocktail containing TEMPO free radical, NaClO2, and NaOCl to give L-N-Boc-N-methyl-β-hydroxyvaline (2) in 87% yield. Coupling of β-hydroxyvaline 2 and (S)-2-hydroxy-3-methylbutanoate (15) was accomplished by using the methodology of Mitsunobu to provide depsipeptide Boc-(S)-HOMeVal-(R)-Hmb (4) for use as a building block in the synthesis of the cyclic antifungal depsipeptide aureobasidin B.Key words: N-methylated amino acid, serine, depsipeptide, aureobasidin.

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Yang, Bin, Kantapat Chansaenpak, Hongmiao Wu, et al. "Silver-promoted (radio)fluorination of unsaturated carbamates via a radical process." Chemical Communications 53, no. 24 (2017): 3497–500. http://dx.doi.org/10.1039/c7cc01393k.

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The intramolecular fluorocyclization of unsaturated carbamates proceeds via a cyclization/1,2-(hetero)aryl migration/fluorination cascade involving an unusual radical process, and provides a straightforward access to (radio)fluorinated oxazolidin-2-ones, oxazolidine-2,4-diones and 1,3-oxazinan-2-ones.

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Husain, Syed Masood, Roland Fröhlich, Dirk Schepmann, and Bernhard Wünsch. "Enantioselective Synthesis of a 2,2-Disubstituted Tetrahydro-3- benzazepine as Novel NMDA Receptor Antagonist." Zeitschrift für Naturforschung B 65, no. 2 (2010): 191–96. http://dx.doi.org/10.1515/znb-2010-0216.

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The tricyclic oxazolidines trans-4 and cis-4 were interconverted upon treatment with allyltrimethylsilane/ TiCl4. The oxazolidine trans-4 was diastereoselectively reacted with PhMgBr to yield the 4,4-disubstituted 3-benzazepinone 6, along with two side products. An X-ray crystal structure analysis of 6 proved the (R)-configuration of the stereogenic center C-4 and thus the retention of configuration. Reduction of 6 with AlCl3/LiAlH4 (1/3) followed by hydrogenolysis with H2, Pd/C resulted in the formation of enantiomerically pure 2-methyl-2-phenyl-tetrahydro-3-benzazepine 11 which has a moderate affinity (Ki = 496 nM) to the PCP binding site of the NMDA receptor.

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Nogueira, Thais C. M., Alessandra C. Pinheiro, James L. Wardell, Marcus V. N. de Souza, Jordan P. Abberley та William T. A. Harrison. "Weak C—H...O and C—H...π hydrogen bonds and π–π stacking interactions in a series of fourN′-[(E)-(aryl)methylidene]-N-methyl-2-oxo-1,3-oxazolidine-4-carbohydrazides". Acta Crystallographica Section C Structural Chemistry 71, № 8 (2015): 647–52. http://dx.doi.org/10.1107/s2053229615012450.

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Oxazolidin-2-ones are widely used as protective groups for 1,2-amino alcohols and chiral derivatives are employed as chiral auxiliaries. The crystal structures of four differently substituted oxazolidinecarbohydrazides, namelyN′-[(E)-benzylidene]-N-methyl-2-oxo-1,3-oxazolidine-4-carbohydrazide, C12H12N3O3, (I),N′-[(E)-2-chlorobenzylidene]-N-methyl-2-oxo-1,3-oxazolidine-4-carbohydrazide, C12H12ClN3O3, (II), (4S)-N′-[(E)-4-chlorobenzylidene]-N-methyl-2-oxo-1,3-oxazolidine-4-carbohydrazide, C12H12ClN3O3, (III), and (4S)-N′-[(E)-2,6-dichlorobenzylidene]-N,3-dimethyl-2-oxo-1,3-oxazolidine-4-carbohydrazide, C13H13Cl2N3O3, (IV), show that an unexpected mild-condition racemization from the chiral starting materials has occurred in (I) and (II). In the extended structures, the centrosymmetric phases, which each crystallize with two molecules (AandB) in the asymmetric unit, formA+Bdimers linked by pairs of N—H...O hydrogen bonds, albeit with different O-atom acceptors. One dimer is composed of one molecule with anSconfiguration for its stereogenic centre and the other with anRconfiguration, and possesses approximate local inversion symmetry. The other dimer consists of eitherR,RorS,Spairs and possesses approximate local twofold symmetry. In the chiral structure, N—H...O hydrogen bonds link the molecules intoC(5) chains, with adjacent molecules related by a 21screw axis. A wide variety of weak interactions, including C—H...O, C—H...Cl, C—H...π and π–π stacking interactions, occur in these structures, but there is little conformity between them.

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Barbera, Vincenzina, Sara Musto, Giuseppe Infortuna, et al. "SERINOL DERIVATIVES FOR THE SUSTAINABLE VULCANIZATION OF DIENE ELASTOMERS." Rubber Chemistry and Technology 91, no. 4 (2018): 701–18. http://dx.doi.org/10.5254/rct.18.81528.

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ABSTRACT 2-amino-1,3-propandiol (serinol) was used as the starting building block of synthetic pathways that led to the preparation of innovative chemicals suitable as ingredients for rubber compounds. Serinol based reactions were performed in the frame of a sustainable process, in the absence of any solvent and catalyst, with aldehydes and ketones, such as acetone, cinnamaldehyde and camphor. The synthesis of either imines or oxazolidines was obtained with high selectivity. Serinol, imine and oxazolidine derivatives of serinol were used as accelerator for the vulcanization of diene rubbers. They were proved to be efficient secondary accelerators in silica based compounds based on poly(styrene-co-butadiene) in place of diphenyl guanidine. The kinetics of vulcanization was investigated for natural rubber based compounds in the absence of any filler. With respect to serinol, the imine derivatives were able to enhance the induction time of vulcanization and to afford a similar vulcanization rate.

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Couture, Philippe, and John Warkentin. "Chemistry of cyclic aminooxycarbenes." Canadian Journal of Chemistry 75, no. 9 (1997): 1281–94. http://dx.doi.org/10.1139/v97-154.

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Анотація:

A series of oxazolidin-2-ylidenes and one tetrahydro-1,3-oxazin-2-ylidene, generated by thermolysis of Δ3-1,3,4-oxadiazolines in benzene at 90 °C, were intercepted by insertion into the OH bond of phenols. In two cases the initial products rearranged to N-(2-aryloxyethyl)-N-methylformamides. The activation energy for rotation about the amide CN bond of those ultimate products was measured as 20.4 kcal/mol. The aminooxycarbenes reacted with two equivalents of methyl or phenyl isocyanate to give spiro-fused hydantoins. Major products from the reactions of the N-carbonyl carbenes with dimethyl acetylenedicarboxylate or with methyl propiolate were 2-oxazolines resulting from apparent acyl transfers from N to C in the proposed dipolar intermediates; minor products of 1:2 (carbene:trap) stoichiometry were also observed. Keywords: nucleophilic carbene, aminooxycarbene, oxadiazoline, amide rotation, oxazolidine.

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Beyzaei, Hamid, Reza Aryan, and Zahra Keshtegar. "Synthesis of New Imidazolidine and Tetrahydropyrimidine Derivatives." Advances in Chemistry 2014 (July 14, 2014): 1–4. http://dx.doi.org/10.1155/2014/834641.

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Анотація:

Synthesis of new imidazolidine and tetrahydropyrimidine derivatives 3a, b and 4a–c as cyclic 1,3-diamines under two reaction conditions (A and B) is described. Under reaction conditions-A, a suspension of (E)-2-cyano-2-(oxazolidin-2-ylidene)ethanethioamide 1 (1 eq.) and diaminoalkanes 2a–e (2 eq.) in absolute ethanol is heated under reflux for 16–22 h to afford 3a, b and 4a–c. Alternatively, under reaction conditions-B, a solution of thioamide 1 (1 eq.) in diaminoalkanes 2a–e (3 eq.) is stirred under solvent-free conditions at room temperature for 3 days to give desired products. Reaction conditions-A for having higher yields, shorter reaction times, and required less diamines is more effective than reaction conditions-B. Oxazolidine ring opening is observed by reacting compound 1 with all of the diamines 2a–e, but the thioamide group only reacts with nonbulky diamines 2a, b. The chemical structures of novel compounds were confirmed by 1H NMR, 13C NMR, elemental analysis, and FT-IR spectrometry.

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