- Metal-free, redox-neutral, site-selective access to heteroarylamine via direct radical?radical cross-coupling powered by visible light photocatalysis
-
Transition-metal-catalyzed C?N bond-forming reactions have emerged as fundamental and powerful tools to construct arylamines, a common structure found in drug agents, natural products, and fine chemicals. Reported herein is an alternative access to heteroarylamine via radical?radical cross-coupling pathway, powered by visible light catalysis without any aid of external oxidant and reductant. Only by visible light irradiation of a photocatalyst, such as a metal-free photocatalyst, does the cascade single-electron transfer event for amines and heteroaryl nitriles occur, demonstrated by steady-state and transient spectroscopic studies, resulting in an amine radical cation and aryl radical anion in situ for C?N bond formation. The metal-free and redox economic nature, high efficiency, and site-selectivity of C?N cross-coupling of a range of available amines, hydroxylamines, and hydrazines with heteroaryl nitriles make this protocol promising in both academic and industrial settings.
- Zhou, Chao,Lei, Tao,Wei, Xiang-Zhu,Ye, Chen,Liu, Zan,Chen, Bin,Tung, Chen-Ho,Wu, Li-Zhu
-
p. 16805 - 16813
(2020/11/09)
-
- Base-promoted aromatic [3,3] sigmatropic rearrangement of N-acyl-O-arylhydroxylamine derivatives
-
The base-promoted aromatic [3,3] sigmatropic rearrangement of N-acyl-O-arylhydroxylamines giving α-(2-hydroxyphenyl)amides was successfully demonstrated. The substrates were prepared from N-substituted hydroxylamines by N-acylation followed by copper(I)-mediated O-arylation with boronic acids. Treatment of the substrates with lithium hexamethyldisilazide (LiHMDS) in THF at 0 °C to room temperature generated the corresponding amide enolates. The aromatic [3,3] rearrangement of the enolates provided the desired products in moderate to good yields. A crossover experiment produced only intramolecular products and clarified that the reaction proceeds via the aromatic [3,3] sigmatropic rearrangement, not a bond-cleavage–recombination process. Our method is a formal α-arylation of amides.
- Tayama, Eiji,Hirano, Kazuki
-
p. 665 - 673
(2019/01/04)
-
- Structural Requirements of Histone Deacetylase Inhibitors: SAHA Analogs Modified on the Hydroxamic Acid
-
Histone deacetylase (HDAC) proteins have emerged as targets for anti-cancer therapeutics, with several inhibitors used in the clinic, including suberoylanilide hydroxamic acid (SAHA, vorinostat). Because SAHA and many other inhibitors target all or most o
- Bieliauskas, Anton V.,Weerasinghe, Sujith V.W.,Negmeldin, Ahmed T.,Pflum, Mary Kay H.
-
p. 373 - 382
(2016/05/19)
-
- Effect of Substituents and Stability of Transient Aluminum-Aminals in the Presence of Nucleophiles
-
Disubstituted hydroxylamines are synthesized and used to form aluminum-amide complexes. These reagents mask carbonyl groups in situ via nucleophilic addition. The stability and utility of the aluminum-aminals are presented in the context of selectively controlling nucleophilic addition on substrates with multiple carbonyl groups.
- Barrios, Francis J.,Springer, Brannon C.,Hazlitt, Robert A.,Colby, David A.
-
p. 175 - 180
(2015/05/05)
-
- Phytotoxic effects of selected N-benzyl-benzoylhydroxamic acid metallo-oxygenase inhibitors: Investigation into mechanism of action
-
Treatment of Arabidopsis thaliana with 100 μM hydroxamic acids F1 and F2, found previously to inhibit carotenoid cleavage dioxygenase enzyme CCD1, was found to cause chlorophyll bleaching and phytotoxicity. A further set of hydroxamic acid analogues was synthesised, and these compounds were found to be phytotoxic towards A. thaliana at 16-400 μM, and to show some phytoxicity towards broad-leaved weeds C. album and S. media at 100 μM. Compound F1 was found to inhibit p-hydroxy-phenylpyruvate dioxygenase (HPPD), a known herbicide target (IC50 30 μM), but compounds F5 and F8 showed no inhibition of HPPD, despite F8 showing higher levels of phytotoxicity. Plants grown in the presence of F1 or F5 that were treated with 50 μM homogentisic acid showed partial recovery of growth, indicating some inhibition of HPPD in planta. These are the first hydroxamic acid inhibitors reported for HPPD, but the results indicate that inhibition of HPPD is only partly responsible for the observed phytotoxicity, and that another unknown metalloenzyme is also targeted by these compounds.
- Sergeant, Martin J.,Harrison, Peter J.,Jenkins, Robert,Moran, Graham R.,Bugg, Timothy D. H.,Thompson, Andrew J.
-
p. 3461 - 3465
(2013/11/06)
-
- HERBICIDAL COMPOSITIONS
-
A herbicidal formulation comprising a compound of formula (I) where R1 is alkyl or H; R2, R3, R4 and R5 are independently selectable from H, halide, -NO2, -SO2R', -OH, -Oalkyl where R' is alkyl or aminoalkyl; and R6 is a substituted or non-substituted alkyl, and/or substituted or non-substituted aryl.
- -
-
Page/Page column 7
(2010/06/15)
-
- PLANT DEVELOPMENT CONTROL COMPOSITION
-
A method of stimulating germination in plant seeds and/or releasing plant tissue or plant organs from dormancy, comprising applying to a seed, plant, plant organ or plant tissue a compound of formula (I): where: R1 is alkyl or H; R2,
- -
-
Page/Page column 9; 10
(2010/06/15)
-
- Solid phase parallel synthesis of tertiary amines
-
Described is method for preparing tertiary amines comprising sequential, exhaustive alkylation of a hydroxylamine derivative and cleavage of the O—N bond using the following steps: a) reacting the hydroxylamine derivative with an alkylating agent or with
- -
-
Page/Page column 4
(2008/06/13)
-
- o-Iodoxybenzoic Acid (IBX) as a Viable Reagent in the Manipulation of Nitrogen- and Sulfur-Containing Substrates: Scope, Generality, and Mechanism of IBX-Mediated Amine Oxidations and Dithiane Deprotections
-
o-Iodoxybenzoic acid (IBX), a highly versatile hypervalent iodine(V) reagent, was found to efficiently mediate the dehydrogenation of amines in addition to facilitating the oxidative cleavage of dithioacetals and dithioketals. Through the development of relevant IBX-based protocols, a plethora of useful synthetic intermediates, including imines, oximes, ketones, and aromatic N-heterocycles, were found to be readily accessible under notably mild conditions. Further investigation of these transformations led to the elucidation of valuable mechanistic details, resulting in the conclusion that they proceed via ionic rather than single electron transfer (SET) pathways.
- Nicolaou,Mathison, Casey J. N.,Montagnon, Tamsyn
-
p. 5192 - 5201
(2007/10/03)
-
- BF3-promoted hydrostannation of N-heteroatom-substituted imines for the reduction of C=N bond
-
Hydrostannation of N-heteroatom-substituted imines such as oxime ethers, hydrazones, oximes, nitrones, and N-sulfonyl imines using a combination of Bu3SnH and BF3·OEt2 has been systematically studied. Not only aromatic aldimines but also kitimines and aliphatic imines were reduced to give the corresponding amines.
- Ueda, Masafumi,Miyabe, Hideto,Namba, Megumi,Nakabayashi, Toshiki,Naito, Takeaki
-
p. 4369 - 4371
(2007/10/03)
-
- General combinatorial synthesis of tertiary amines on solid support. A novel conditional release strategy based on traceless linking at nitrogen
-
A novel solid phase synthesis of tertiary amines involving iodide-induced cleavage of the N-O bond of resin bound alkoxyammonium intermediates is described. The quaternary intermediates were assembled via sequential reductive aminations followed by alkylation. Cleavage from the solid support was induced by iodide ion or base, to afford the target tertiary amines in excellent purity.
- Gustafsson, Magnus,Olsson, Roger,Andersson, Carl-Magnus
-
p. 133 - 136
(2007/10/03)
-
- N-nitroso-N,O-dialkylhydroxylamines: Preparation, structure, and mechanism of the hydronium ion catalysed solvolytic nitrous oxide extrusion reaction
-
Eleven N-nitroso-N,O-dialkylhydroxylamines, RN(NO)OR′, have been prepared and the mechanisms of their hydronium ion catalysed solvolyses in aqueous solution which liberate nitrous oxide have been investigated. All reactions are first-order in substrate and first-order in hydronium ion, and the second-order rate constants at 25°C vary over a range of less than 140 in spite of considerable variation in substrate structure (R ranges from methyl to 4-methoxybenzyl to 2-adamantyl, for example) and changes in solvent composition (water with up to 50% methanol or 66% acetonitrile). Enthalpies and entropies of activation are qualitatively similar throughout the range (ΔH?= 72-93 kJ mol-1 and ΔS? = -19 to -57 J K-1 mol-1) which, with the product analyses, are accommodated by a mechanism involving pre-equilibrium protonation of the substrates followed by rate-limiting dissociation to give RN2O+ and HOR′. The oxodiazonium ion intermediate, RN2O+, then dissociates further to give the carbenium ion intermediate, R+, or suffers direct nucleophilic displacement of N2O by solvent (the external nucleophile) or by R′OH (the internal nucleophile liberated in the initial fragmentation). The carbenium ion, R+ (if formed), suffers nucleophilic capture either by solvent or by R′OH. When acetonitrile is the co-solvent (rather than methanol) for the N-(2-adamantyl) substrate 3g, the product of the Ritter reaction, 2-acetamidoadamantane, is detected. These nitrous oxide liberating reactions are compared with the nitric oxide liberating reactions of related N-nitrosohydroxylamines, and the origin of the difference between them is identified. The N(1)-nitroso group in the N,O-dibenzyl compound 3c is shown by X-ray crystallography to be essentially coplanar with the C and O atoms also bonded to N(1).
- Bhat, J. Ishwara,Clegg, William,Maskill, Howard,Elsegood, Mark R.J.,Menneer, Iain D.,Miatt, Peter C.
-
p. 1435 - 1446
(2007/10/03)
-
- Acyclic oxyiminium ions. Mannich reactions and addition of grignard reagents
-
Acyclic oxyiminium ion generation from secondary hydroxylamines (4a,b and 6a,b) and formaldehyde in the presence of acetic acid is reported. Trapping these electrophiles with 2-methyl furan, pyrrole or indole affords a series of novel O-benzyl tertiary hydroxylamines in good to excellent yield. Benzotriazole mediated synthetic methodology has also been successfully developed to generate oxyiminium ions which react with Grignard reagents, to give novel O-benzyl tertiary hydroxylamines. (C) 2000 Elsevier Science Ltd.
- Grigg,Rankovic,Thoroughgood
-
p. 8025 - 8032
(2007/10/03)
-
- Reductive cleavage of N-O bonds in hydroxylamines and hydroxamic acid derivatives using samarium diiodide
-
An efficient process for the reductive cleavage of N-O bonds using samarium diiodide is detailed for a variety of structural types to define the scope and limitations of the method. The reduction is shown to be compatible with base sensitive substrates such as trifluoroacetamide derivatives, which cannot be reduced satisfactorily using aluminum amalgam or sodium amalgam. Direct quenching of the reduction mixture with acylating agents is demonstrated to provide high yields of protected amines in a one-pot process from the N-O derivatives.
- Keck, Gary E.,Wager, Travis T.,McHardy, Stanton F.
-
p. 11755 - 11772
(2007/10/03)
-
- β-lactam derivatives as inhibitors of human cytomegalovirus protease
-
The development of novel monobactam inhibitors of HCMV protease incorporating a carbon side chain at C-4 and a urea function at N-1 is described. Substitution with small groups at the C-3 position of the β- lactam ring gave an increase in enzymatic activity and in stability; however, a lack of selectivity against other serine proteases was noted. The use of both triand tetrasubstituted urea functionalities gave effective inhibitors of HCMV protease. Benzyl substitution of the urea moiety was beneficial, especially when strong electron-withdrawing groups where attached at the para position. Modest antiviral activity was found in a plaque reduction assay.
- Yoakim, Christiane,Ogilvie, William W.,Cameron, Dale R.,Chabot, Catherine,Guse, Ingrid,Haché, Bruno,Naud, Julie,O'Meara, Jeff A.,Plante, Raymond,Déziel, Robert
-
p. 2882 - 2891
(2007/10/03)
-
- Asymmetric Synthesis of (-)-Actinonin and (-)-epi-Actinonin
-
The highly asymmetric induction imparted by the iron chiral auxiliary 5-C5H5)Fe(CO)(PPh3)> is exploited in the preparation of homochiral (R)- and (S)-α-pentylsuccinates.Their application in the synthesis of (-)-actinonin and (-)-epi-actinoni
- Bashiardes, George,Bodwell, Graham J.,Davies, Stephen G.
-
p. 459 - 470
(2007/10/02)
-
- BIS(TRI-n-BUTYLSTANNYL)BENZOPINACOLATE: PREPARATION AND USE AS A MEDIATOR OF INTERMOLECULAR FREE RADICAL REACTIONS
-
Bis(tri-n-butylstannyl)benzopinacolinate (2) serves as a thermal source of tri-n-butylstannyl radicals and mediates intermolecular coupling of selected alkyl halides to O-benzylformaldoxime and electron deficient olefins.A free radical non-chain mechanism is proposed for these reactions.
- Hart, David J.,Krishnamurthy, Ramanarayanan,Pook, Lori M.,Seely, Franklin L.
-
p. 7819 - 7822
(2007/10/02)
-
- Quinoline hydroxamates and their use as modulators of arachidonic acid metabolic pathways
-
This invention relates to new chemical compounds possessing valuable pharmaceutical activity, particularly as lipoxygenase inhibitors possessing anti-inflammatory and anti-allergic properties.
- -
-
-
- THE ASYMMETRIC SYNTHESIS OF (-)-ACTINONIN USING THE IRON CHIRAL AUXILIARY 5-C5H5)Fe(CO)(PPh3)>
-
The asymmetric synthesis of the α-pentyl succinate fragment of (-)-Actinonin is achived using the chiral ironacetyl S-(+)-5-C5H5)-Fe(CO)(PPh3)COCH3> and subsequently converted to (-)-Actinonin in an overall yield of 41percent.
- Bashiardes, George,Davies, Stephen G.
-
p. 6509 - 6512
(2007/10/02)
-
- Erythro-Directive Reduction of α-Substituted Alkanones by Means of Hydrosilanes in Acidic Media
-
Hydrosilane reduced α-oxy and α-amino ketones and β-keto acid derivatives in trifluoroacetic acid to afford the corresponding erythro alcohols with high diastereoselectivity.The reaction proceeded without racemization at the carbon α to the carbonyl group.The erythro-directive reduction was explained in terms of the proton-bridged Cram cyclic model and successfully applied to the synthesis of physiologically important amino alcohols such as l-ephedrine, l-methoxamine, and erythro-2-methyl-3-piperidino-1-phenylpropanol.
- Fujita, Makoto,Hiyama, Tamejiro
-
p. 5415 - 5421
(2007/10/02)
-
- Compositions stabilized with ethers of di- and tri-substituted hydroxylamines
-
Various di- and tri-substituted hydroxylamine derivatives are effective in stabilizing organic materials against oxidative, thermal and actinic degradation, said derivatives being particularly effective as color improvers and process stabilizers in organi
- -
-
-
- REDUCTION OF OXIMES WITH HYDROSILANE/H(1+) REAGENT
-
Hydrosilane/H+ reagent reduced oximes in good yields.Stereospecific reduction of (2-acetoxy-1-phenylpropylidene) benzyloxyazane (3) was observed; the (E)-isomer gave erythro-1-phenyl-1-benzyloxyamino-2-propanol (4) in 99percent selectivity, whe
- Fujita, Makoto,Oishi, Haruhito,Hiyama, Tamejiro
-
p. 837 - 838
(2007/10/02)
-