83077-00-3Relevant academic research and scientific papers
Visible-Light-Mediated Generation of Nitrogen-Centered Radicals: Metal-Free Hydroimination and Iminohydroxylation Cyclization Reactions
Davies, Jacob,Booth, Samuel G.,Essafi, Stephanie,Dryfe, Robert A. W.,Leonori, Daniele
supporting information, p. 14017 - 14021 (2016/01/25)
The formation and use of iminyl radicals in novel and divergent hydroimination and iminohydroxylation cyclization reactions has been accomplished through the design of a new class of reactive O-aryl oximes. Owing to their low reduction potentials, the inexpensive organic dye eosin Y could be used as the photocatalyst of the organocatalytic hydroimination reaction. Furthermore, reaction conditions for a unique iminohydroxylation were identified; visible-light-mediated electron transfer from novel electron donor-acceptor complexes of the oximes and Et3N was proposed as a key step of this process.
Metal-free one-pot synthesis of benzofurans
Ghosh, Raju,Stridfeldt, Elin,Olofsson, Berit
, p. 8888 - 8892 (2014/07/22)
Ethyl acetohydroxamate was efficiently arylated with diaryliodonium salts at room temperature under transition-metal-free conditions. The obtained O-arylated products were reacted in situ with ketones under acidic conditions to yield substituted benzo[b]furans through oxime formation, [3,3]-rearrangement, and cyclization in a fast and operationally simple one-pot fashion without using excess reagents. Alternatively, the O-arylated products could be isolated or transformed in situ to aryloxyamines or O-arylaldoximes. The methodology was applied to the synthesis of Stemofuran A and the formal syntheses of Coumestan, Eupomatenoid 6, and (+)-machaeriol B. Just add salt! A metal-free, room temperature arylation of ethyl acetohydroxamate, followed by an in situ reaction with ketones under acidic conditions yielded substituted benzo[b]furans in a fast and operationally simple one-pot fashion without using excess reagents (see scheme). Alternatively, the O-arylated products could be isolated, hydrolyzed in situ to aryloxyamines, or transformed to O-arylaldoximes. The efficiency of the methodology was demonstrated by the formal synthesis of several biologically active benzofurans.
PROCESS FOR PREPARING BENZOFURAN DERIVATIVES SUBSTITUTED AT POSITION 5
-
Paragraph 0110-0112, (2013/07/05)
The disclosure relates to a process for preparing benzofuran derivatives of general formula I: in which R, R1, and R2 are as defined in the disclosure; by coupling the hydroxylamine with a diketone of general formula III: in order to form an oxime that is then cyclized by heating in order to form the desired compound.
Chemoselective amide formation using O-(4-nitrophenyl)hydroxylamines and pyruvic acid derivatives
Kumar, Sonali,Sharma, Rashi,Garcia, Megan,Kamel, Joseph,McCarthy, Caroline,Muth, Aaron,Phanstiel, Otto
, p. 10835 - 10845 (2013/02/23)
A series of O-(4-nitrophenyl)hydroxylamines were synthesized from their respective oximes using a pulsed addition of excess NaBH3CN at pH 3 in 65a-75% yield. Steric hindrance near the oxime functional group played a key role in both the ease by which the oxime could be reduced and the subsequent reactivity of the respective hydroxylamine. Reaction of the respective hydroxylamines with pyruvic acid derivatives generated the desired amides in good yields. A comparison of phenethylamine systems bearing different leaving groups revealed significant differences in the rates of these systems and suggested that the leaving group ability of the Na-OR substituent plays an important role in determining their reactivity with pyruvic acid. Competition experiments (in 68% DMSO/phosphate buffered saline) using 1 equiv of N-phenethyl-O-(4-nitrophenyl)hydroxylamine and 2 equiv of pyruvic acid in the presence of other nucleophiles such as glycine, cysteine, phenol, hexanoic acid, and lysine demonstrated that significant chemoselectivity is present in this reaction. The results suggest that this chemoselective reaction can occur in the presence of excess α-amino acids, phenols, acids, thiols, and amines.
NEW PROCESS FOR PREPARING DIKETONES AND MEDICAMENTS
-
Page/Page column 43, (2010/04/27)
There is provided a process for the preparation of a compound of formula (III), wherein X and Y are as described in the description. Such compounds may, for example, be useful intermediates in the synthesis of drugs such as Dronedarone. There is also provided a process for the preparation of a compound of formula (I).
NEW PROCESS FOR PREPARING HYDROXYLAMINES AND MEDICAMENTS
-
Page/Page column 49, (2010/11/03)
There is provided a process for the preparation of a compound of formula (II), wherein R1, R2, R3 and R4 are as described in the description. Such compounds may, for example, be useful intermediates in the synthesis of drugs such as Dronedarone.
PROCESS FOR PREPARING BENZOFURANS
-
Page/Page column 37, (2009/05/29)
There is provided a process for the preparation of a compound of formula (I), wherein R1, R2, R3, R4, X and Y are as described in the description. Such compounds may, for example, be useful intermediates in the synthesis of drugs such as Dronedarone.
Synthesis of Phenoxyamines
Castellino, Angelo J.,Rapoport, Henry
, p. 1348 - 1352 (2007/10/02)
Treatment of phenols with 2,4-dinitrophenoxyamine leads to the synthesis of phenoxyamines through an amine exchange reaction.Yields for this reaction are sensitive to the pKa of the phenol in a manner explainable in terms of a competing bimolecular decomposition reaction involving the 2,4-dinitrophenoxyamines.By use of an appropriately sustituted phenol, this phenomenon can be exploited to give high yields of phenoxyamines having oxygenated substitution patterns that were unattainable by previous methods.
Acid-Catalyzed Solvolysis of N-Sulfonyl- and N-Acyl-O-arylhydroxylamines. Phenoxenium Ions
Endo, Yasuyuki,Shudo, Koichi,Okamoto, Toshihiko
, p. 6393 - 6397 (2007/10/02)
The acid-catalyzed reaction of N-acyl- and N-sulfonyl-O-arylhydroxylamines with benzene proceeded quite smoothly to give 2- and 4-hydroxybiphenyls.The results of product analysis, the orientation of the reaction, and the effects of substituents on the nitrogen atom and on the phenyl ring suggested a mechanism that involves a phenoxenium ion.The phenoxenium ion was trapped by benzene and other various nucleophiles.
