نتایج جستجو برای: imines
تعداد نتایج: 2655 فیلتر نتایج به سال:
Alkynyl aziridines can be obtained from the catalytic asymmetric aziridination (AZ reaction) of alkynyl imines with diazo compounds in high yields and high asymmetric inductions mediated by a chiral boroxinate or BOROX catalyst. In contrast to the AZ reaction with aryl- and alkyl-substituted imines, alkynyl imines react to give cis-substituted aziridines with both diazo esters and diazo acetami...
We have explored the isoelectronic replacement of the C═C double bond found at the core of many nonsteroidal estrogen ligands with a simple Schiff base (C═N). Di- and triaryl-substituted imine derivatives were conveniently prepared by the condensation of benzophenones with various anilines without the need for phenolic hydroxy protection. Most of these imines demonstrated high affinity for the ...
Although azides have been widely used in nitrene transfer reactions, in situ generation of N-H imines from azides for downstream transformations has rarely been explored. We report copper-mediated formation of N-unsubstituted aliphatic imines from easily available aliphatic azides using a customized phenanthroline-based ligand (L1*). Through trapping in situ-generated N-H imines, multisubstitut...
The stereoselectivity of the Staudinger reactions involving monosubstituted ketenes with electron acceptor substituents was investigated experimentally by determination of the product stereochemistry and theoretically via DFT calculations. The results indicate that imines preferentially attack the less sterically hindered exo-side of the ketenes to generate zwitterionic intermediates. Subsequen...
Despite the current interest in selenium chemistry [1—6], oxidations by selenium dioxide remained limited to only a few classes of compounds, mainly alkenes and carbonyl compounds, in addition to some special cases [7, 8]. Selenium dioxide is the cheapest and most convenient selenium reagent, and an extension of its applications to other types of com pounds is therefore of considerable interes...
Chiral polyborate based Brønsted acids prepared from the VANOL and VAPOL ligands are known to catalyze the reaction of diarylmethyl imines with diazoesters to give cis-aziridines. In the present work, this same catalyst is shown to catalyze the reaction of the same imines with diazoacetamides to give trans-aziridines with the same high asymmetric inductions as seen with cis-aziridines, enabling...
The preparation of C-iodo-N-Ts-aziridines with excellent cis-diastereoselectivity has been achieved in high yields by the addition of diiodomethyllithium to N-tosylimines and N-tosylimine-HSO2Tol adducts. This addition-cyclization protocol successfully provided a wide range of cis-iodoaziridines, including the first examples of alkyl-substituted iodoaziridines, with the reaction tolerating both...
A series of structurally diverse spiro 1,3-oxazines were conveniently prepared from three-component reaction conjugated imines, dialkyl acetylenedicarboxylates (DAAD), and N,N'-disubstituted parabanic acids in dry dichloromethane without catalyst. Initially, various imines synthesized aniline derivatives with cinnamaldehyde. Subsequently, DAAD N,N'-substituted led to mixture the corresponding s...
The current syntheses of imines from benzylamines are often performed in organic solvents or under harsh reaction conditions. Clean oxidation of primary benzylamines to imines has been successfully achieved using H(2)O(2) in water at room temperature catalyzed by V(2)O(5). Among the 10 imine products, 5 of them precipitated from the reaction and led pure products after simple filtration. No org...
Electron-deficient alkenes undergo organocatalysed formal [3+2]-cycloaddition with isatin-derived imines, generating complex spirocyclic products high yield and stereoselectivity.
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