3376-40-7Relevant articles and documents
Polyfunctionalized biaryls accessed by a one-pot nucleophilic aromatic substitution and sigmatropic rearrangement reaction cascade under mild conditions
Liang, Dong-Dong,Guo, Shen-Yi,Tong, Shuo,Wang, Mei-Xiang
, (2021/02/09)
A practical synthetic method has been developed for polyfunctionalized biaryls based on a facile one-pot nucleophilic aromatic substitution (SNAr) reaction and [5,5]- or [3,3]-sigmatropic rearrangement reaction cascade. Under mild basic conditions, N-arylhydroxylamines reacted with o-activated fluoro (het)arenes to form N,O-diarylhydroxylamine intermediates which underwent spontaneously selective [5,5]-sigmatropic rearrangement reaction to produce diverse functionalized 4-amino-4′-hydroxy-1,1′-biaryls. A sequential SNAr reaction and [3,3]-sigmatropic rearrangement took place between N-arylhydroxylamines and 2-fluoropyridine derivatives or 4-fluorobenzonitrile to afford functionalized 2-amino-2′-hydroxy-1,1′-biaryls. As invaluable and unique building blocks, the resulting biaryls were applied in the straightforward synthesis of N2,O2-coronarene, carbazole, aza- and diaza carbazole derivatives.
A Modified System for the Synthesis of Enantioenriched N-Arylamines through Copper-Catalyzed Hydroamination
Ichikawa, Saki,Zhu, Shaolin,Buchwald, Stephen L.
supporting information, p. 8714 - 8718 (2018/07/14)
Despite significant recent progress in copper-catalyzed enantioselective hydroamination chemistry, the synthesis of chiral N-arylamines, which are frequently found in natural products and pharmaceuticals, has not been realized. Initial experiments with N-arylhydroxylamine ester electrophiles were unsuccessful and, instead, their reduction in the presence of copper hydride (CuH) catalysts was observed. Herein, we report key modifications to our previously reported hydroamination methods that lead to broadly applicable conditions for the enantioselective net addition of secondary anilines across the double bond of styrenes, 1,1-disubstituted olefins, and terminal alkenes. NMR studies suggest that suppression of the undesired reduction pathway is the basis for the dramatic improvements in yield under the reported method.
Synthesis of 3-alkylbenzoxazolones from N-alkyl-N-arylhydroxylamines by contiguous O-trichloroacetylation, trichloroacetoxy ortho-shift, and cyclization sequence
Ram, Ram N.,Soni, Vineet Kumar
, p. 11935 - 11947 (2014/01/06)
Benzoxazolone pharmacophore is present in clinical pharmaceuticals, drug candidates, and many compounds having a wide spectrum of biological activities. The methods available for the synthesis of benzoxazolones have limited diversity due to problems in accessibility and air-sensitivity of diversely substituted o-aminophenols from which they are generally prepared by cyclocarbonylation with phosgene or its equivalents. The present paper describes a mild method for the synthesis of 3-alkylbenzoxazolones from easily accessible and air-stable nitroarenes. Nitroarenes were converted to N-alkyl-N-arylhydroxylamines in two steps involving partial reduction to arylhydroxylamines followed by selective N-alkylation. Treatment of N-alkyl-N-arylhydroxylamines with trichloroacetyl chloride and triethylamine afforded 3-alkylbenzoxazolones generally in good yields through an uninterrupted three-step sequence involving O-trichloroacetylation, N→Cortho trichloroacetoxy shift, and cyclization in a single pot at ambient temperatures. The present method is mild, wide in scope, economical, and regioselective. Many sensitive groups like alkyl and aryl esters, amide, cyano, and the carbon-carbon double bond survive the reaction.
Equilibrium acidities and homolytic bond dissociation energies of N-H and/or O-H bonds in N-phenylhydroxylamine and its derivatives
Bordwell, Frederick G.,Liu, Wei-Zhong
, p. 8777 - 8781 (2007/10/03)
The equilibrium acidities (pK(HA) values) in DMSO of the following hydroxylamines have been measured: (1) N-phenylhydroxylamine and its p-bromo and p-cyano derivatives, (2) N-benzyl-N-phenylhydroxylamine and its p-bromo and p-cyano derivatives, (3) O-benzyl-N-phenylhydroxylamine, (4) N-benzoylphenylhydroxylamine and its p-bromo and p-cyano derivatives, and (5) N-hydroxylpiperidine. The BDEs of the O-H and/or N-H bonds in these 11 weak acids have been estimated by combining their pK(HA) values with the oxidation potentials of their conjugate bases according to the following equation: BDE(HA) = 1.37pK(HA) + 23.1E(ox)(A-) + 73.3 kcal/mol.
Improved Preparation of α,N-Diphenylnitrones and N-Benzyl-N-Phenylhydroxylamines by direct Oxidation of Secondary Anilines
Gorrod, John W.,Gooderham, Nigel J.
, p. 261 - 265 (2007/10/02)
A simple and rapid method for the oxidation of secondary anilines to α,N-diphenylnitrones and the subsequent reduction to secondary N-benzyl-N-phenylhydroxylamines is described.
ADDITION 1-3 D'HYDROSILANES ET STANNANES SUR DIVERSES NITRONES : RADICAUX NITROXYDES α-METALLES R3M-C-N.-O ET O- ET C-METALLA-HYDROXYLAMINES R3M-O-N-C-H ET R3M-C-N-OH
Riviere, Pierre,Richelme, Suzanne,Riviere-Baudet, Monique,Satge, Jacques,Riley, Paul I.,et al.
, p. 1663 - 1683 (2007/10/02)
Free radical 1,3-addition of silanes or stannanes to various nitrones generally leads to corresponding O-organometallohydroxylamines.The α-metallonitroxide radicals =-M-C-N.-O, obtained by trapping silyl or stannyl-centred radicals with an appropriate nitrone, have been characterised by e.s.r. spectroscopy.The O-stannylhydroxylamines are generally sufficiently stable to be isolated by distillation under vacuum.The less stable O-germyl or O-silylhydroxylamines decompose readily upon heating or by photolysis by competing intra- and intermolecular processes.Under special conditions favouring the formation of silylanions (MeNO2, NEt3), a competitive 1,3-dipolar addition of phenyldichloro- or trichlorosilane with the nitrone leads to the unstable C-metallohydroxylamine =-M-C-N-OH .
