نتایج جستجو برای: hydroxylamines
تعداد نتایج: 1000 فیلتر نتایج به سال:
The intramolecular 1,3-dipolar cycloaddition of isovanillin derived N-aryl hydroxylamines possessing ortho-allylic dipolarophiles affords novel benzo analogues of tricyclic isoxazolidines that can be readily transformed into functionalized lactams, γ-aminoalcohols and oxazepines. The corresponding N-unsubstituted hydroxylamines give rise to tetrahydroisoquinolines. Anxiogenic properties of thes...
Hydroxylamines gradually undergo oxidation to their oximes on being dissolved in organic solvent (e.g. methanol). This phenomenon was followed by (1)H-NMR and liquid chromatography-mass spectrometry (LC-MS). The oxidation rate was estimated from the peak area observed on the mass chromatogram at the protonated molecule or fragment ion on LC-atmospheric pressure chemical ionization (APCI)-MS. Th...
The synthesis of enantiopure N-benzylidene nitrones of N-hydroxy-alpha-amino acids and their incorporation using standard Fmoc-based peptide chemistry into solid-supported peptide chains is described. Deprotection and resin cleavage affords N-terminal peptide hydroxylamines, which are the key substrates for chemoselective ligations with C-terminal peptide alpha-ketoacids. This general route is ...
?-hydroxylamines exhibit higher reactivity toward cyclic carbonates compare to regular amines and allowed access fully biobased polyhydroxyurethanes.
tions have been developed as fundamentally important crosscoupling reactions. In general, the heteroatom nucleophiles in these reactions have been largely limited to alkylamines, anilines, carboxylates and phenols. Our laboratory is interested in searching the synthetically useful heteroatom nucleophiles for the synthesis of functionalized allylic compounds (Fig. 1). As our successful examples,...
Alpha-phenyl-N-t-butyl nitrone (PBN), a spin trap, scavenges hydroxyl radicals, protects tissues from oxidative injury, and delays senescence of both normal human lung fibroblasts (IMR90) and senescence-accelerated mice. N-t-butyl hydroxylamine and benzaldehyde are the breakdown products of PBN. N-t-Butyl hydroxylamine delays senescence of IMR90 cells at concentrations as low as 10 microM compa...
Gold(I) complexes of a chiral phosphoric acid-functionalized phosphine the CPA-Phos series enable enantioselective multicomponent reactions between aldehydes, hydroxylamines and cyclic yne-enones, leading to 3,4-dihydro-1H-furo[3,4-d][1,2]oxazines. This represents rare example highly reaction in gold(I) catalysis. The proceed at low catalyst loading provide high yields, total diastereoselectivi...
Oximes, its ether derivatives and the corresponding hydroxylamines rearrange to secondary amines when reacted with PhSiH3 B(C6F5)3 as catalyst. Computations suggest a reduction–rearrangement be slightly favored over Beckmann-type sequence.
Herein, twoN-substituted coumaryl hydroxylamines (compounds 1a and 1b) with long aliphatic chains were prepared in 8 steps with a novel synthetic protocol. They served as derivatization agents for aldehydes by the formation of nitrones under mild conditions, which can be readily analysed by LC-MS with good chromatographic performance, excellent fluorescent response, and high ionization strength...
Using bakers' yeast as a biocatalyst, the chemoselective reduction of aromatic nitro compounds bearing electron-withdrawing groups gave the corresponding hydroxylamines with good to excellent conversion under mild conditions.
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