- Evidence for an Isocyanate Formation in the Alkaline Hydrolysis of N1-Alkyl Derivatives of Chlorpropamide, Inhibitors of Aldehyde Dehydrogenase
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Trapping of a propyl isocyanate intermediate and entropies of activation data are consistent with an elimination-addition mechanism AxhDH + DN (E1cB) for the hydrolysis of 1-alkyl-1--3-n-propylurea, the N1-alkyl derivatives of chlorpropamide, inhibitors of aldehyde dehydrogenase.
- Bergon, M.,Vigroux, A.,Tisnes, P.
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Read Online
- Rhodium-catalyzed aerobic N-alkylation of sulfonamides with alcohols
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By using the famous Wilkinson's catalyst, N-alkylation of sulfonamides can be easily realized under mild aerobic conditions by using alcohols as the alkylating reagent, giving monoalkylated sulfonamides in high yields and selectivities with water produced as the only byproduct. This advantageous aerobic method is potentially general in substrate scope that it can also be applied to other amides, amines and alcohols.
- Feng, Sun Lin,Liu, Chuan Zhi,Li, Qiang,Yu, Xiao Chun,Xu, Qing
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Read Online
- Triflic acid mediated functionalization of α-hydroxyphosphonates: Route for sulfonamide phosphonates
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An operationally simple synthetic method for (±)-α-aryl/ methylsulfonamidomethylphosphonates and new (±)-γ-aryl/methyl sulfonamidomethylvinylphosphonates has been developed through straightforward reactions of (±)-α-hydroxyphosphonates with sulfonamides in the presence of triflic acid (TfOH) at room temperature in a vessel open to air. For γ-dimethylallylhydroxyphosphonate, the (E)-1,3-butadienylphosphonate was formed quantitatively using TfOH while FeCl3 afforded the expected product in moderate yield unpredictably. The favourable sulfonoamidation of benzyl alcohol is also observed when TfOH was used for α- hydroxyphosphonates having a benzyloxy group. The Royal Society of Chemistry 2013.
- Pallikonda, Gangaram,Chakravarty, Manab
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Read Online
- Discovery of N-amido-phenylsulfonamide derivatives as novel microsomal prostaglandin E2 synthase-1 (mPGES-1) inhibitors
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Our previous research showed that N-carboxy-phenylsulfonyl hydrazide (scaffold A) could reduce LPS-stimulated PGE2 levels in RAW 264.7 macrophage cells by an inhibition of mPGES-1 enzyme. However, a number of scaffold A derivatives showed the drawbacks such as the formation of regioisomers and poor liver metabolic stability. In order to overcome these synthetic and metabolic problems, therefore, we decided to replace N-carboxy-phenylsulfonyl hydrazide (scaffold A) with N-carboxy-phenylsulfonamide (scaffold B) or N-amido-phenylsulfonamide frameworks (scaffold C) as a bioisosteric replacement. Among them, MPO-0186 (scaffold C) inhibited the production of PGE2 (IC50: 0.24 μM) in A549 cells via inhibition of mPGES-1 (IC50: 0.49 μM in a cell-free assay) and was found to be approximately 9- and 8-fold more potent than MK-886 as a reference inhibitor, respectively. A molecular docking study theoretically suggests that MPO-0186 could inhibit PGE2 production by blocking the PGH2 binding site of mPGES-1 enzyme. Furthermore, MPO-0186 demonstrated good liver metabolic stability and no significant inhibition observed in clinically relevant CYP isoforms except CYP2C19. This result provides a potential starting point for the development of selective and potent mPGES-1 inhibitor with a novel scaffold.
- Kim, Misong,Kim, Geuntae,Kang, Minji,Ko, Dohyeong,Nam, Yunchan,Moon, Chang Sang,Kang, Heung Mo,Shin, Ji-Sun,Werz, Oliver,Lee, Kyung-Tae,Lee, Jae Yeol
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- Method for synthesizing N-alkyl sulfonamide in water
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The invention discloses a method for synthesizing N-alkyl sulfonamide in water, in particular to a method for synthesizing an N-alkyl sulfonamide derivative from a sulfonamide derivative and alcohol,and a water-soluble iridium complex is adopted to catalyze the reaction of N-alkyl sulfonamide. Compared with the previous synthesis method, the method has the advantages that a reaction equivalent substrate is used in the reaction process, so that raw material waste is avoided; weak base is used, and reaction conditions are mild; non-toxic and harmless pure water is used as a solvent in the reaction, only water is generated as a by-product, the atom reaction economy is high, and the requirement of green chemistry is met.
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Paragraph 0108; 0109; 0110; 0111; 0112
(2020/12/30)
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- The: N -alkylation of sulfonamides with alcohols in water catalyzed by a water-soluble metal-ligand bifunctional iridium complex [Cp?Ir(biimH2)(H2O)][OTf]2
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The iridium complex [Cp?Ir(biimH2)(H2O)][OTf]2 (Cp? = η5-pentamethylcyclopentadienyl, biimH2 = 2,2′-biimidazole) was synthesized and developed as a new-type of water-soluble metal-ligand bifunctional catalyst for the N-alkylation of poorly nucleophilic sulfonamides with alcohols in water. In the presence of catalyst (1 mol%) and Cs2CO3 (0.1 equiv.), a series of desirable products was obtained in 74-91% yields under microwave irradiation. Mechanistic experiments revealed that the presence of NH units in the imidazole ligand is crucially important for the catalytic activity of the iridium complex. Notably, this research would facilitate the process of water-soluble metal-ligand bifunctional catalysis for the hydrogen autotransfer process.
- Ai, Yao,Liu, Pengcheng,Liang, Ran,Liu, Yan,Li, Feng
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p. 10755 - 10762
(2019/07/15)
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- Method for catalytic synthesis of N-benzyl benzene sulfonamide compounds by boric acid/oxalic acid catalytic system under microwave radiation
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The invention discloses a method for catalytic synthesis of N-benzyl benzene sulfonamide compounds by a boric acid/oxalic acid catalytic system under microwave radiation. The method includes: adoptingbenzyl alcohol and derivatives thereof and benzene sulfonamide derivatives as raw materials, adopting the boric acid/oxalic acid system as a catalyst, and adopting fluorobenzene as a solvent; performing reaction in a microwave reactor under certain temperature and power conditions, performing vacuum concentration after reaction for a period of time, and subjecting a product to column chromatographic purification to realize efficient catalytic preparation of the N-benzyl benzene sulfonamide compounds. Compared with the prior art, the method has advantages of evidently higher reaction speed than that of conventional heating, mild reaction conditions, simplicity in operation, high yield, safety, low cost and environmental friendliness.
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Paragraph 0031; 0077
(2018/09/11)
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- Nondirected, cu-catalyzed sp3 C-H aminations with hydroxylamine-based amination reagents: Catalytic and mechanistic studies
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This work demonstrates the use of hydroxylamine-based amination reagents RSO2NH-OAc for the nondirected, Cu-catalyzed amination of benzylic C-H bonds. The amination reagents can be prepared on a gram scale, are benchtop stable, and provide benzylic C-H amination products with up to 86% yield. Mechanistic studies of the established reactivity with toluene as substrate reveal a ligand-promoted, Cu-catalyzed mechanism proceeding through Ph-CH2(NTsOAc) as a major intermediate. Stoichiometric reactivity of Ph-CH2(NTsOAc) to produce Ph-CH2-NHTs suggests a two-cycle, radical pathway for C-H amination, in which the decomposition of the employed diimine ligands plays an important role.
- Wang, Anqi,Venditto, Nicholas J.,Darcy, Julia W.,Emmert, Marion H.
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supporting information
p. 1259 - 1268
(2017/05/29)
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- Nickel-catalyzed product-controllable amidation and imidation of sp3 C-H bonds in substituted toluenes with sulfonamides
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A nickel-catalyzed product-controllable imidation and amidation of sp3 C-H bonds in substituted toluenes with sulfonamides were developed. Based on the change of the reaction time and atmosphere from N2 to O2, this reaction proceeded in high yields and excellent selectivity under different conditions. Mechanistic details were also described.
- Li, Ze-lin,Jin, Li-kun,Cai, Chun
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supporting information
p. 1317 - 1320
(2017/02/15)
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- Ruthenium(II) carbonyl complexes designed with arsine and PNO/PNS ligands as catalysts for N-alkylation of amines via hydrogen autotransfer process
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A series of phosphine-functionalized hydrazone/thiosemicarbazone ligands and their corresponding ruthenium(II) carbonyl complexes of the type [RuCl(CO)(AsPh3)(L)] (1-5) [L = 2-(2-(diphenylphosphino)benzylidene)benzoic acid hydrazone (PNO-BHy), 2-(2-(diphenylphosphino)benzylidene)nicotinic acid hydrazone (PNO-NHy), 2-(2-(diphenylphosphino)benzylidene)-2-furoic hydrazone (PNO-FHy), 2-(2-(diphenylphosphino)benzylidene)-4-ethyl-3-thiosemicarbazone (PNS-EtTs), 2-(2-(diphenylphosphino)benzylidene)-4-cyclohexyl-3-thiosemicarbazone (PNS-CyTs)] have been synthesized based on the ligands with different electronic and steric effects. These complexes were characterized by elemental analyses and various spectral methods. The solid-state structure of the complex 4 was determined by single-crystal X-ray diffraction method. In all of the complexes, the ligand was bound to the Ru(II) center via the PNO/PNS donor atoms. All the ruthenium(II) complexes were demonstrated as highly efficient catalysts for the synthesis of secondary amines/amides by the coupling of primary amines/amides with alcohols at low catalyst loading, and the maximum yield was obtained up to 98%. The N-alkylation reaction can be readily carried out under moderate conditions, and release of water is the sole byproduct. In addition, the effects of substituents on the ligand, solvents, base and catalyst loading on the catalytic activity of the complexes have been investigated. Advantageously, only one equivalent of the alcohol was consumed in the process.
- Ramachandran, Rangasamy,Prakash, Govindan,Nirmala, Muthukumaran,Viswanathamurthi, Periasamy,Malecki, Jan Grzegorz
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supporting information
p. 130 - 140
(2015/06/22)
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- Ruthenium(II) complexes containing a phosphine-functionalized thiosemicarbazone ligand: Synthesis, structures and catalytic C-N bond formation reactions via N-alkylation
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A series of ruthenium(II) complexes incorporating a thiosemicarbazone chelate tethered with a diphenylphosphine pendant have been studied. Thus, [(PNS-Et)RuCl(CO)(PPh3)] (1), [N,S-(PNS-Et)RuH(CO)(PPh3)2] (2) and [(PNS-Et)RuCl(PPh3)] (3) were synthesized by reactions of various RuII precursors with 2-(2-(diphenylphosphino)benzylidene)-N-ethylthiosemicarbazone (PNS-Et). However, complexation of PNS-Et with an equimolar amount of [RuCl2(dmso)4] resulted in two different entities [(PNS-Et)RuCl(dmso)2] (4) and [(PNS-Et)2Ru] (5) with different structural features in a single reaction. All the RuII complexes have been characterized by analytical and various spectroscopic techniques. Compounds 1-5 were recrystallized, and the X-ray crystal structures have been reported for 1, 2 and 5. In the complexes 1 and 3-5 the ligand coordinated in a tridentate monobasic fashion by forming PNS five- and six-membered rings, whereas in 2, the ligand coordinated in a bidentate monobasic fashion by forming a strained NS four-membered ring. Furthermore, compounds 1-5 showed catalytic activity in N-alkylation of heteroaromatic amines. Notably, complexes 1-3 were found to be very efficient catalysts toward N-alkylation of a wide range of heterocyclic amines with alcohols. In the presence of a catalytic amount of 2 with 50 mol% of KOH, N1,C5-dialkylation of 4-phenylthiazol-2-amine has been investigated. Reaction of in situ generated aldehyde with amine yields the N1,C5-dialkylated products through the hydride ion transformation from alcohol. Complexes 1-3 also catalyzed a variety of coupling reactions of benzyl alcohols and sulfonamides, which were realized often with 99% isolated yields. Advantageously, only one equivalent of the primary alcohol was consumed in the process.
- Ramachandran, Rangasamy,Prakash, Govindan,Selvamurugan, Sellappan,Viswanathamurthi, Periasamy,Malecki, Jan Grzegorz,Linert, Wolfgang,Gusev, Alexey
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p. 11405 - 11422
(2015/03/05)
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- Direct Alkylation of Amines with Alcohols Catalyzed by Base
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A base-catalyzed/promoted transition-metal-free direct alkylation of amines with alcohols has been developed, giving the desired amines in generally high yields from either aromatic or aliphatic alcohols. On the basis of the 1H NMR and in situ IR (React-IR) monitoring experiments, isotope-labeling experiments, as well as control experiments, a novel "hemiaminal" model is proposed to understand the mechanism, which explains the formation of the "extra" aldehyde in the reaction.
- Li, Qiang-Qiang,Xiao, Zu-Feng,Yao, Chuan-Zhi,Zheng, Hong-Xing,Kang, Yan-Biao
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supporting information
p. 5328 - 5331
(2015/11/18)
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- Metal-free direct construction of sulfonamides via iodine- mediated coupling reaction of sodium sulfinates and amines at room temperature
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A simple, practical, and metal-free protocol has been developed for the synthesis of sulfonamides from sodium sulfinates and various amines through an iodine-mediated SN bond formation reaction at room temperature. This green reaction is cost-effective, operationally straightforward, and especially proceeds under very mild conditions to afford the target products in good to excellent yields (up to 98%).
- Wei, Wei,Liu, Chunli,Yang, Daoshan,Wen, Jiangwei,You, Jinmao,Wang, Hua
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supporting information
p. 987 - 992
(2015/03/30)
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- Green and scalable aldehyde-catalyzed transition metal-free dehydrative N-alkylation of amides and amines with alcohols
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In contrast to the borrowing hydrogen-type N-alkylation reactions, in which alcohols were activated by transition metal-catalyzed anaerobic dehydrogenation, the addition of external aldehydes was accidentally found to be a simple and effective protocol for alcohol activation. This interesting finding subsequently led to an efficient and green, practical and scalable aldehyde-catalyzed transition metal-free dehydrative N-alkylation method for a variety of amides, amines, and alcohols. Mechanistic studies revealed that this reaction most possibly proceeds via a simple but interesting transition metal-free relay race mechanism. Copyright
- Xu, Qing,Li, Qiang,Zhu, Xiaogang,Chen, Jianhui
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supporting information
p. 73 - 80
(2013/03/13)
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- Palladium-catalyzed N-alkylation of amides and amines with alcohols employing the aerobic relay race methodology
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Possibly because homogeneous palladium catalysts are not typical borrowing hydrogen catalysts and ligands are thus ineffective in catalyst activation under conventional anaerobic conditions, they had not been used in the N-alkylation reactions of amines/amides with alcohols in the past. By employing the aerobic relay race methodology with Pd-catalyzed aerobic alcohol oxidation being a more effective protocol for alcohol activation, ligand-free homogeneous palladiums are successfully used as active catalysts in the dehydrative N-alkylation reactions, giving high yields and selectivities of the alkylated amides and amines. Mechanistic studies implied that the reaction most probably proceeds via the novel relay race mechanism we recently discovered and proposed. By employing the aerobic relay race methodology with Pd-catalyzed aerobic alcohol oxidation being a more effective protocol for alcohol activation, ligand-free homogeneous palladiums are successfully used as active catalysts in the dehydrative N-alkylation reactions of amines and amides with alcohols, giving high yields and selectivities of the alkylated amines and amides. Mechanistic studies implied that the reaction most probably proceeds via the novel relay race mechanism we recently discovered and proposed. Copyright
- Yu, Xiaochun,Jiang, Lan,Li, Qiang,Xu, Qing,Xie, Yuanyuan
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p. 2322 - 2332,11
(2020/09/16)
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- Progresses in the pursuit of aldose reductase inhibitors: The structure-based lead optimization step
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Aldose reductase (ALR2) is a crucial enzyme in the development of the major complications of diabetes mellitus. Very recently it has been demonstrated that the ARL2 inhibitor, fidarestat, significantly prevents inflammatory signals (TNF-α, LPS) that cause cancer (colon, breast, prostate and lung), metastasis, asthma, and other inflammatory diseases. Currently, fidarestat is in phase III clinical trial for diabetic neuropathy and was found to be safe. Thus the finding of novel, potent ARL2 inhibitors is today more than in the past in great demand as they can pave the way for a novel therapeutic approach for a number of diseases besides the diabetes. Herein, starting from the virtual screening-derived ALR2 inhibitor S12728 (1), a rational receptor-based lead optimization has been undertaken. The design and synthetic efforts here reported led to the discovery of several new compounds endowed with low micromolar/submicromolar activities.
- Ramunno, Anna,Cosconati, Sandro,Sartini, Stefania,Maglio, Vita,Angiuoli, Sara,La Pietra, Valeria,Di Maro, Salvatore,Giustiniano, Mariateresa,La Motta, Concettina,Da Settimo, Federico,Marinelli, Luciana,Novellino, Ettore
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experimental part
p. 216 - 226
(2012/07/16)
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- Discovery and mechanistic studies of a general air-promoted metal-catalyzed aerobic n- alkylation reaction of amides and amines with alcohols
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The thermodynamically unfavorable anaerobic dehydrogenative alcohol activation to aldehydes and hydridometal species is found to be the bottleneck in metal-catalyzed N-alkylations due to a general and unnoticed catalyst deactivation by amines/amides. Thus, different from the anaerobic dehydrogenation process in borrowing hydrogen or hydrogen autotransfer reactions that require noble metal complexes or addition of capricious ligands for catalyst activation, the water-producing, exothermic, metal-catalyzed aerobic alcohol oxidation is thermodynamically more favorable and the most effective and advantageous aldehyde generation protocol. This leads to a general and advantageous air-promoted metal-catalyzed aerobic N-alkylation methodology that effectively uses many simpler, less expensive, more available, and ligand-free metal catalysts that were inactive under typical anaerobic borrowing hydrogen conditions, avoiding the use of preformed metal complexes and activating ligands and the exclusive requirement of inert atmosphere protection. This aerobic method is quite general in substrate scope and tolerates various amides, amines, and alcohols, revealing its potentially broad utilities and interests in academy and industry. In contrast to the commonly accepted borrowing hydrogen mechanism, based on a thorough mechanistic study and supported by the related literature background, a new mechanism analogous to the relay race game that has never been proposed in metal-catalyzed N-alkylation reactions is presented.
- Liu, Chuanzhi,Liao, Shiheng,Li, Qiang,Feng, Sunlin,Sun, Qing,Yu, Xiaochun,Xu, Qing
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supporting information; scheme or table
p. 5759 - 5773
(2011/09/16)
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- Manganese dioxide catalyzed N-alkylation of sulfonamides and amines with alcohols under air
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By simply running the reactions under air and solvent-free conditions using catalytic amounts of manganese dioxide, a practical and efficient N-alkylation method for a variety of sulfonamides and amines using alcohols as green alkylating reagents was developed.
- Yu, Xiaochun,Liu, Chuanzhi,Jiang, Lan,Xu, Qing
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supporting information; experimental part
p. 6184 - 6187
(2012/01/06)
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- Simple and versatile catalytic system for N-alkylation of sulfonamides with various alcohols
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"Chemical Equation Presented" A simple and versatile catalytic system for N-alkylation of sulfonamides with various alcohols based on a catalytic hydrogen transfer reaction has been developed under a low catalyst loading of [Cp*lrCl2]2 (0.050-1.5 mol %) in the presence of t-BuOK. A variety of N-alkylated sulfonamides were prepared In good to excellent yields. Mechanistic investigations revealed that the key catalytic species in the present system is a sulfonylimido-bridged unsaturated diirldium complex [(Cp*lr)2(μ-NTs)2].
- Zhu, Mingwen,Fujita, Ken-Ichi,Yamaguchi, Ryohei
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supporting information; experimental part
p. 1336 - 1339
(2010/06/15)
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- Borrowing hydrogen in water and ionic liquids: Iridium-catalyzed alkylation of amines with alcohols
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The use of [Cp*IrI2]2 as an efficient catalyst for the alkylation of amines by alcohols in either water or ionic liquid is described. Primary amines are converted into secondary amines, and secondary amines into tertiary amines in the absence of base, and the chemistry has been applied to the synthesis of the analgesic fentanyl. The conversion of primary amines into N-heterocycles by the reaction with diols is also described, along with the N-alkylation of sulfonamides.
- Saidi, Ourida,Blacker, A. John,Lamb, Gareth W.,Marsden, Stephen P.,Taylor, James E.,Williams, Jonathan M. J.
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supporting information; experimental part
p. 1046 - 1049
(2011/03/20)
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- Ruthenium-catalyzed /V-alkylation of amines and sulfonamides using borrowing hydrogen methodology
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The alkylation of amines by alcohols has been achieved using 0.5 mol percent [Ru(p-cymene)CI2]2 with the bidentate phosphines dppf or DPEphos as the catalyst. Primary amines have been converted into secondary amines, and secondary amines into tertiary amines, including the syntheses of Piribedil, Tripelennamine, and Chlorpheniramine. A/-Heterocyclization reactions of primary amines are reported, as well as alkylation reactions of primary sulfonamides. Secondary alcohols requiremore forcing conditions than primary alcohols but are still effective a lkylating agents in the presence of this catalyst.
- Hamid, M. Haniti S. A.,Allen, C. Liana,Lamb, Gareth W.,Maxwell, Aoife C.,Maytum, Hannah C.,et al.
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supporting information; experimental part
p. 1766 - 1774
(2009/07/25)
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- Highly efficient synthesis of functionalized dihydronaphthalenes, tetrahydronaphthalenes, and tetrahydroisoquinolines by iron-catalyzed intramolecular Friedel-Crafts reaction of aryl-containing propargylic alcohols
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An efficient, convenient, and one-pot procedure for the synthesis of a series of new dihydro- and tetrahydronaphthalenes as well as tetrahydroisoquinolines has been established through Lewis acid-catalyzed intramolecular Friedel-Crafts reaction of aryl-substituted propargylic alcohols.
- Huang, Wen,Hong, Longcheng,Zheng, Pengzhi,Liu, Ruiting,Zhou, Xigeng
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body text
p. 3603 - 3610
(2009/09/06)
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- Imido transfer from bis(imido)ruthenium(VI) porphyrins to hydrocarbons: Effect of imido substituents, C-H bond dissociation energies, and Ru VI/V reduction potentials
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[RuVI(TMP)(NSO2R)2] (SO2R = Ms, Ts, Bs, Cs, Ns; R = p-C6H4OMe, p-C6H 4Me, C6H5, p-C6H4-Cl, p-C6H4NO2, respectively) and [Ru VI(Por)(NTs)2] (Por = 2,6-Cl2TPP, F 20-TPP) were prepared by the reactions of [RuII(Por)(CO)] with Phl=NSO2R in CH2Cl2. These complexes exhibit reversible RuVI/V couple with E1/2 = -0.41 to -0.12 V vs Cp2Fe+/10 and undergo imido transfer reactions with styrenes, norbornene, cis-cyclooctene, indene, ethylbenzenes, cumene, 9,10-dihydroanthracene, xanthene, cyclohexene, toluene, and tetrahydrofuran to afford aziridines or amides in up to 85% yields. The second-order rate constants (k2) of the aziridination/amidation reactions at 298 K were determined to be (2.6 ± 0.1) × 10-5 to 14.4 ± 0.6 dm3 mol-1 s-1, which generally increase with increasing RuVI/V reduction potential of the imido complexes and decreasing C-H bond dissociation energy (BDE) of the hydrocarbons. A linear correlation was observed between log K (K is the k2 value divided by the number of reactive hydrogens) and BDE and between log k2 and E1/2(RuVI/V); the linearity in the former case supports a H-atom abstraction mechanism. The amidation by [RuVI(TMP)(NNs) 2] reverses the thermodynamic reactivity order cumene > ethylbenzene/toluene, with K(3° C-H)/K(2° C-H) = 0.2 and K(3° C-H)/K(1° C-H) = 0.8.
- Leung, Sarana Ka-Yan,Tsui, Wai-Man,Huang, Jie-Sheng,Che, Chi-Ming,Liang, Jiang-Lin,Zhu, Nianyong
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p. 16629 - 16640
(2007/10/03)
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- Regioselectivity and the nature of the reaction mechanism in nucleophilic substitution reactions of 2,4-dinitrophenyl X-substituted benzenesulfonates with primary amines
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Second-order rate constants have been measured for the reaction of 2,4-dinitrophenyl X-substituted benzenesulfonates with a series of primary amines. The nucleophilic substitution reaction proceeds through competitive S-O and C-O bond fission pathways. The S-O bond fission occurs dominantly for reactions with highly basic amines or with substrates having a strong electron-withdrawing group in the sulfonyl moiety. On the other hand, the C-O bond fission occurs considerably for the reactions with low basic amines or with substrates having a strong electron-donating group in the sulfonyl moiety, emphasizing that the regioselectivity is governed by both the amine basicity and the electronic effect of the sulfonyl substituent X. The apparent second-order rate constants for the S-O bond fission have resulted in a nonlinear Bronsted-type plot for the reaction of 2,4-dinitrophenyl benzenesulfonate with 10 different primary amines, suggesting that a change in the rate-determining step occurs upon changing the amine basicity. The microscopic rate constants (k1 and k2/k-1 ratio) associated with the S-O bond fission pathway support the proposed mechanism. The second-order rate constants for the S-O bond fission result in good linear Yukawa-Tsuno plots for the aminolyses of 2,4-dinitrophenyl X-substituted benzenesulfonates. However, the second-order rate constants for the C-O bond fission show no correlation with the electronic nature of the sulfonyl substituent X, indicating that the C-O bond fission proceeds through an SNAR mechanism in which the leaving group departure occurs rapidly after the rate-determining step.
- Um, Ik-Hwan,Hong, Jin-Young,Kim, Jung-Joo,Chae, Ok-Mi,Bae, Sun-Kun
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p. 5180 - 5185
(2007/10/03)
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- Competitive Reaction Pathways in the Nucleophilic Substitution Reactions of Aryl Benzenesulfonates with Benzylamines in Acetonitrile
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The reactions of aryl benzenesulfonates (YC6H4SO2OC6H4Z) with benzylamines (XC6H4CH2NH2) in acetonitrile at 65.0 deg C have been studied. The reactons proceed competitevely by S-O (kS-O) and C-O (kC-O) bond scission, but the former provides the major reaction pathway. On the basis of analysis of the Hammet and Broensted coefficients together with the cross-interaction constants ρXY, ρYZ, and ρXZ, stepwise mechanisms are proposed in which the S-O bond cleavage proceeds by rate-limiting formation of a trigonal-bipyramidal pentacoordinate (TBP-5C) intermediate, whereas the C-O bond scission takes place by rate-limiting expulsion of the sulfonate anion (YC6H4SO3-) from a Meisenheimer-type complex.
- Choi, Jin Heui,Lee, Byung Choon,Lee, Hai Whang,Lee, Ikchoon
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p. 1277 - 1281
(2007/10/03)
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