58803-38-6Relevant academic research and scientific papers
Preparation method of derivatives of pyrrole, imidazole, and oxazole
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Paragraph 0014; 0015; 0018, (2017/07/19)
The invention relates to a preparation method of derivatives of pyrrole, imidazole, and oxazole. Specifically, in the presence of triphenyl phosphine, various alkenyl azides carry out cyclization reactions to generate derivatives of pyrrole, imidazole, an
Synthesis of γ-azido-β-ureido ketones and their transformation into functionalized pyrrolines and pyrroles via staudinger/aza-wittig reaction
Fesenko, Anastasia A.,Shutalev, Anatoly D.
, p. 1190 - 1207 (2013/04/10)
A simple two-step procedure yielding γ-azido-β-ureido ketones or/and their cyclic isomers, 6-(1-azidoalkyl)-4-hydroxyhexahydropyrimidin-2- ones, has been developed. The synthesis includes three-component condensation of acetals of 2-azidoaldehydes with urea or methylurea and p-toluenesulfinic acid in aqueous formic acid followed by reaction of the obtained N-[(2-azido-1-tosyl) alkyl]ureas with sodium enolates of α-functionalized ketones. The azido ketones or their cyclic isomers are transformed into ureido-substituted Δ1- or/and Δ2-pyrrolines via Staudinger/aza-Wittig reaction promoted by PPh3. The obtained pyrrolines are converted into 3-functionalized 1H-pyrroles via elimination of urea under acidic conditions. Convenient one-pot syntheses of 1H-pyrroles starting from N-[(2-azido-1-tosyl)alkyl]ureas or γ-azido-β-ureido ketones have been also developed.
Regioselective synthesis of 2,3,4- or 2,3,5-trisubstituted pyrroles via [3,3] or [1,3] rearrangements of O-vinyl oximes
Wang, Heng-Yen,Mueller, Daniel S.,Sachwani, Rachna M.,Kapadia, Rachel,Londino, Hannah N.,Anderson, Laura L.
scheme or table, p. 3203 - 3221 (2011/06/24)
The regioselective synthesis of 2,3,4- or 2,3,5-trisubstituted pyrroles has been achieved via [3,3] and [1,3] sigmatropic rearrangements of O-vinyl oximes, respectively. Iridium-catalyzed isomerization of easily prepared O-allyl oximes enables rapid access to O-vinyl oximes. The regioselectivity of pyrrole formation can be controlled by either the identity of the α-substituent or through the addition of an amine base. When enolization is favored, a [3,3] rearrangement followed by a Paal-Knorr cyclization provides a 2,3,4-trisubstituted pyrrole; when enolization is disfavored, a [1,3] rearrangement occurs prior to enolization to produce a 2,3,5-trisubstituted pyrrole after cyclization. Optimization and scope of the O-allyl oxime isomerization and subsequent pyrrole formation are discussed and mechanistic pathways are proposed. Conditions are provided for selecting either the [3,3] rearrangement or the [1,3] rearrangement product with β-ester O-allyl oxime substrates.
Intramolecular interactions in carbenes derived during the pyrolysis of N-alkenylisoxazolones
Cox, Matthew,Dixon, Michael,Lister, Troy,Prager, Rolf H.
, p. 455 - 460 (2007/10/03)
Flash vacuum pyrolysis of ethyl 3-(3-methyl-5-oxo-2,5-dihydroisoxazole-2- yl)-3-phenylpropenoate yields 4-ethoxy-3-hydroxy-2-methyl-5-phenylpyridine in addition to the expected pyrrole. The structure assignment is based on two-dimensional NMR and computat
