41319-82-8Relevant academic research and scientific papers
Three-Component Homo 3 + 2 Dipolar Cycloaddition. A Diversity-Oriented Synthesis of Tetrahydro-1,2-oxazines and FR900482 Skeletal Congeners
Young, Ian S.,Kerr, Michael A.
, p. 139 - 141 (2004)
(Equation presented) The reaction of nitrones, formed in situ by reaction of hydroxylamines with aldehydes, with 1,1-cyclopropanediesters results in the formation of tetrahydro-1,2-oxazines via a homo 3 + 2 dipolar cycloaddition. This three-component coupling allows for the formation of a diverse array of cycloadducts with excellent diastereoselectivity (>95%) and yields (66-96%). The procedure has been used in the two-step preparation of congeners of the FR900482 skeleton.
Redox-Neutral Selenium-Catalysed Isomerisation of para-Hydroxamic Acids into para-Aminophenols
Chuang, Hsiang-Yu,Schupp, Manuel,Meyrelles, Ricardo,Maryasin, Boris,Maulide, Nuno
supporting information, p. 13778 - 13782 (2021/03/31)
A selenium-catalysed para-hydroxylation of N-aryl-hydroxamic acids is reported. Mechanistically, the reaction comprises an N?O bond cleavage and consecutive selenium-induced [2,3]-rearrangement to deliver para-hydroxyaniline derivatives. The mechanism is studied through both 18O-crossover experiments as well as quantum chemical calculations. This redox-neutral transformation provides an unconventional synthetic approach to para-aminophenols.
Effect of substituents on the rate of oxidation of anilines with peroxomonosulfate monoanion (HOOSO3-) in aqueous acetonitrile: A mechanistic study
Meenakshisundaram, Subbiah,Selvaraju,Made Gowda,Rangappa, Kanchugarakoppal S.
, p. 649 - 657 (2007/10/03)
Mechanistic studies on the oxidation of 18 meta-, para-, and ortho-substituted anilines (Ans) by HOOSO3- in aqueous acetonitrile medium have been performed. The reaction can be characterized by the experimental rate equation, -d[HSO5-]/dt = k[An][HSO5-] The addition of p-toluenesulfonic acid (TsOH) retards the reaction. The increase in the reactivity of anilines as the medium is made more aqueous is interpreted. The reaction is enhanced by electron-donating groups on the amine in the series consistent with the rate-limiting nucleophilic attack of the amine on the persulfate oxygen. The proposed mechanism involves the conversion of phenylhydroxylamine to nitrosobenzene in a fast step. The ESR study reveals the absence of free radicals in the reaction. Various attempts have been made to analyze the experimental rate constants in terms of LFER plots. Improved correlations are obtained with σ- values and the σ- form of the Yukawa-Tsuno equation.
SYNTHESIS OF TETRAHYDRO-1,2-OXAZINES BY THE CYCLOADDITION OF NITRONES WITH CYCLOPROPANES
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Page 75-76, (2010/02/08)
One aspect of the present invention relates to a method of preparing tetrahydro-1,2- oxazines comprising the step of combining a nitrone and a cyclopropane in the presence of a Lewis acid. Another aspect of the present invention relates to a method of preparing a tetrahydro-1,2-oxazine, comprising the step of combining an aldehyde and a hydroxylamine in the presence of a Lewis acid to generate a nitrone in situ, then admixing a cyclopropane. Another aspect of the present invention relates to converting a tetrahydro-l,2-oxazine to a pyrrolidine comprising the step of admixing a tetrahydro-1,2-oxazine and a reducing agent.
Synthesis and preliminary evaluation of a library of polycyclic small molecules for use in chemical genetic assays
Tan, Derek S.,Foley, Michael A.,Stockwell, Brent R.,Shair, Matthew D.,Schreiber, Stuart L.
, p. 9073 - 9087 (2007/10/03)
(-)-Shikimic acid, 3, was converted into both enantiomers of epoxycyclohexenol carboxylic acid, 7, which were attached to a solid support via a photocleavable linker. Tandem acylation-1,3-dipolar cycloaddition with nitrones 11a-g yielded tetracyclic templates 12a-g. After development of several efficient coupling reactions of iodobenzyl tetracycles 12b-d and completion of extensive validation protocols, a splitpool synthesis yielded a binary encoded library calculated to contain 2.18 million polycyclic compounds. These compounds are compatible with miniaturized cell-based 'forward' chemical genetic assays designed to explore biological pathways and 'reverse' chemical genetic assays designed to explore protein function. As a simple illustration of the potential of these compounds, several were shown to activate a TGF-β-responsive reporter gene in mammalian cells.
Novel Reactions: Part I - Facile Synthesis of Substituted ortho-Chloranilines from Nitrobenzene Derivatives
Ayyangar, N. R.,Kalkote, U. R.,Nikrad, P. V.
, p. 872 - 877 (2007/10/02)
N-Substituted benzo and acetohydroxamic acids (5), prepared from N-arylhydroxylamines and benzoyl or acetyl chloride, react readily with thionyl chloride at low temperature to give ortho-chloroanilide derivatives (6) in good yield.The latter (6) on hydrolysis give ortho-chloroanilines (10).Since the N-arylhydroxylamines are obtained from nitroarenes by partial reduction, the overall reaction amounts to the preparation of 10 from nitroarenes.
Kinetics and Mechanism of the Bamberger Rearrangement. Part 4. Rearrangement of Sterically Hindered Phenylhydroxylamines to 4-Aminophenols in Aqueous Sulphuric Acid Solution
Sone, Takaaki,Hamamoto, Kazuhiro,Seiji, Yoshiyuki,Shinkai, Seiji,Manabe, Osamu
, p. 1596 - 1598 (2007/10/02)
The rates of the Bamberger rearrangement of sterically hindered phenylhydroxylamines have been determined in aqueous sulphuric acid solution and the substituent effects (in particular, the steric effects) are discussed.The rate constants for phenylhydroxylamines with 2-substituents (Me, Cl, I) satisfied the Taft equation: log krel = ρ*?* - δES with ρ*-1.93 and δ-1.16.The result shows that steric hindrance of the substituents, in addition to the electron-donating effect, has an accelerating effect on the rates of the Bamberger rearrangement.The rate constants for 3-substituted 2-methylphenylhydroxylamines were generally greater than those for 5-substituted 2-methylphenylhydroxylamines.The difference was attributed to the 'buttressing effect' of neighbouring 3-substituents.This is the first example of steric acceleration of the Bamberger rearrangement.
