- Synthesis of large macrocyclic azacalix[n]pyridines (n = 6 - 9) and their complexation with fullerenes C60 and C70
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Large methylazacalix[n]pyridines (n = 6-9) were synthesized effectively from the Pd-catalyzed macrocyclic fragment coupling reactions between α,ω-dibrominated and α,ω-diaminated linear oligomers. As macrocyclic host molecules, they formed a 1:1 complex with fullerenes C 60 and C70 with association constants ranging from 3 × 104 to 1 × 105 M-1.
- Zhang, En-Xuan,Wang, De-Xian,Zheng, Qi-Yu,Wang, Mei-Xiang
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Read Online
- Method for catalyzing N-alkylation of aminopyridine
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The invention discloses a method for catalyzing N-alkylation of aminopyridine. The method comprises the step of reacting an aminopyridine compound with an alkylation raw material in the presence of a heterogeneous catalyst to obtain an N-alkylated aminopyridine compound. The alkylation reaction has high activity and selectivity, is simple to operate and low in catalyst price, does not need other reaction steps, is beneficial to large-scale industrial production, and compared with previous reports, does not need to use a large amount of noble metals, can be continuously carried out, and does not use other expensive organic raw materials or reducing agents in the process. Generation of a large amount of organic waste liquid and solid waste is avoided, and collection operation of process products is simple.
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Paragraph 0087-0091
(2021/08/07)
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- Effect of the ancillary ligand in N-heterocyclic carbene iridium(III) catalyzed N-alkylation of amines with alcohols
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A series of air-stable N-heterocyclic carbene (NHC) Ir(III) complexes (Ir1-6), bearing various combinations of chlorine, pyridine and NHC ligands, were assayed for the N-alkylation of amines with alcohols. It was found that Ir3, with two monodentate 1,3-bis-methyl-imidazolylidene (IMe) ligands, emerged as the most active complex. A large variety of amines and primary alcohols were efficiently converted into mono-N-alkylated amines in 53–96% yields. As a special highlight, for the challenging MeOH, selective N-monomethylation could be achieved using KOH as a base under an air atmosphere. Moreover, this catalytic system was successfully applied to the gram-scale synthesis of some valuable compounds.
- Feng, Xinshu,Huang, Ming
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- Ru-Catalyzed Selective Catalytic Methylation and Methylenation Reaction Employing Methanol as the C1 Source
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Methanol can be employed as a green and sustainable methylating agent to form C-C and C-N bonds via borrowing hydrogen (BH) methodology. Herein we explored the activity of the acridine-derived SNS-Ru pincer for the activation of methanol to apply it as a C1 building block in different reactions. Our catalytic system shows great success toward the β-C(sp3)-methylation reaction of 2-phenylethanols to provide good to excellent yields of the methylated products. We investigated the mechanistic details, kinetic progress, and temperature-dependent product distribution, which revealed the slow and steady generation of in situ formed aldehyde, is the key factor to get the higher yield of the β-methylated product. To establish the environmental benefit of this reaction, green chemistry metrics are calculated. Furthermore, dimerization of 2-naphthol via methylene linkage and formation of N-methylation of amine are also described in this study, which offers a wide range of substrate scope with a good to excellent yield.
- Biswas, Nandita,Srimani, Dipankar
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p. 10544 - 10554
(2021/07/31)
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- N-Methylation of Amines with Methanol in the Presence of Carbonate Salt Catalyzed by a Metal-Ligand Bifunctional Ruthenium Catalyst [(p-cymene)Ru(2,2′-bpyO)(H2O)]
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A ruthenium complex [(p-cymene)Ru(2,2′-bpyO)(H2O)] was found to be a general and efficient catalyst for the N-methylation of amines with methanol in the presence of carbonate salt. Moreover, a series of sensitive substituents, such as nitro, ester, cyano, and vinyl groups, were tolerated under present conditions. It was confirmed that OH units in the ligand are crucial for the catalytic activity. Notably, this research exhibited the potential of metal-ligand bifunctional ruthenium catalysts for the hydrogen autotransfer process.
- Liu, Peng,Tung, Nguyen Thanh,Xu, Xiangchao,Yang, Jiazhi,Li, Feng
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p. 2621 - 2631
(2021/02/27)
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- Recyclable covalent triazine framework-supported iridium catalyst for the N-methylation of amines with methanol in the presence of carbonate
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An iridium complex Cp*Ir@CTF, which is synthesized by the coordinative immobilization of [Cp*IrCl2]2 on a functionalized covalent triazine framework (CTF), was found to be a general and highly efficient catalyst for the N-methylation of amines with methanol in the presence of carbonate. Under environmentally benign conditions, a variety of desirable products were obtained in high yields with complete selectivities and functional group friendliness. Furthermore, the synthesized catalyst could be recycled by simple filtration without obvious loss of catalytic activity after sixth cycle. Notably, this research exhibited the potential of covalent triazine framework-supported transition metal catalysts for hydrogen autotransfer process.
- Liu, Peng,Yang, Jiazhi,Ai, Yao,Hao, Shushu,Chen, Xiaozhong,Li, Feng
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p. 281 - 290
(2021/03/26)
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- Efficient methylation of anilines with methanol catalysed by cyclometalated ruthenium complexes
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Cyclometalated ruthenium complexes4-10allow the effective methylation of anilines with methanol to selectively giveN-methylanilines. This hydrogen autotransfer procedure proceeds under mild conditions (60 °C) in a practical manner (NaOH as base). Mechanistic investigations suggest an active homogenous ruthenium complex and β-hydride elimination of methanol as the rate determining step.
- Piehl, Patrick,Amuso, Roberta,Spannenberg, Anke,Gabriele, Bartolo,Neumann, Helfried,Beller, Matthias
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p. 2512 - 2517
(2021/04/22)
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- Bimetallic Bis-NHC-Ir(III) Complex Bearing 2-Arylbenzo[d]oxazolyl Ligand: Synthesis, Catalysis, and Bimetallic Effects
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Herein, an unprecedented bimetallic bis-NHC Cp*Ir complex 1 bearing 2-arylbenzo[d]oxazolyl and NHC ligands is reported. A significant increase in activity was observed for N-methylation of amines and reduction of aldehydes with MeOH catalyzed by 1 compared to the monometallic analogues (2-11). Under the optimal conditions, it showed to be highly effective in N-methylation of nitroarenes with MeOH as both C1 and H2 source. Substrates, including aromatic amines, ketones, and nitro compounds with various functional groups, can be well-tolerated. Mechanistic studies and DFT calculation highlight the significance of bimetallic centers cooperativity.
- Huang, Shuang,Hong, Xi,Cui, He-Zhen,Zhan, Bing,Li, Zhi-Ming,Hou, Xiu-Feng
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p. 3514 - 3523
(2020/10/09)
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- Ruthenium(II) Complexes of Heteroditopic N-Heterocyclic Carbene Ligands: Efficient Catalysts for C-N Bond Formation via a Hydrogen-Borrowing Strategy under Solvent-Free Conditions
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Both imidazol-2-ylidene (ImNHC) and 1,2,3-triazol-5-ylidene (tzNHC) have evolved to be elite groups of N-heterocyclic carbene (NHC) ligands for homogeneous catalysis. To develop efficient ruthenium(II)-based catalysts incorporating these ligands for C-N bond-forming reactions via hydrogen-borrowing methodology, we utilized chelating ligands integrated with ImNHC and mesoionic tzNHC donors connected via a CH2 spacer with a diverse triazole backbone. The synthesized ruthenium(II) complexes 3 are found to be highly efficient for C-N bond formation across a wide range of primary amine and alcohol substrates under solvent-free conditions, and among all of the complexes studied here, catalyst 3a with a mesityl substituent displayed maximum activity. To our delight, catalyst 3a is also effective for the selective mono-N-methylation of various anilines utilizing methanol as a coupling partner, known to be relatively more difficult than other alcohols. Furthermore, complex 3a also delivers various substituted quinolines successfully via the reaction of 2-aminobenzyl alcohol with several secondary alcohols. Importantly, catalyst 3a exhibited the highest activity among the reported ruthenium(II) complexes for both the N-benzylation of aniline [achieving a turnover number (TON) of 50000] and the realization of quinoline 8a by reacting 2-aminobenzyl alcohol with 2-phenylethanol (attaining a TON of 30000).
- Donthireddy,Mathoor Illam, Praseetha,Rit, Arnab
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supporting information
p. 1835 - 1847
(2020/01/31)
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- Synthesis and Catalytic Activity of Iron Hydride Ligated with Bidentate N-Heterocyclic Silylenes for Hydroboration of Carbonyl Compounds
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We report the synthesis of a novel bidentate N-heterocyclic silylene (NHSi) ligand, N-(LSi:)-N-methyl-2-pyridinamine (1) (L = PhC(NtBu)2), and the first bischelate disilylene iron hydride, [(Si,N)(Si,C)Fe(H)(PMe3)] (2), and monosilylene iron hydride, [(Si,C)Fe(H)(PMe3)3] (2′), through Csp2-H activation of the NHSi ligand. Compounds 1 and 2 were fully characterized by spectroscopic methods and single-crystal X-ray diffraction analysis. Density functional theory calculations indicated the multiple-bond character of the Fe-Si bonds and the π back-donation from Fe(II) to the Si(II) center. Moreover, the strong donor character of ligand 1 enables 2 to act as an efficient catalyst for the hydroboration reaction of carbonyl compounds at room temperature. Chemoselective hydroboration is attained under these conditions. This might be the first example of hydroboration of ketones and aldehydes catalyzed by a silylene hydrido iron complex. A catalytic mechanism was suggested and partially experimentally verified.
- Qi, Xinghao,Zheng, Tingting,Zhou, Junhao,Dong, Yanhong,Zuo, Xia,Li, Xiaoyan,Sun, Hongjian,Fuhr, Olaf,Fenske, Dieter
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p. 268 - 277
(2019/01/21)
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- Methylation of Amines and Ketones with Methanol Catalyzed by an Iridium Complex Bearing a 2-Hydroxypyridylmethylene Fragment
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Reaction of complex [Cp?Ir(HOC5H3CH2C5H3OH)Cl][Cl] (1) with AgOTf generated the product [Cp?Ir(HOC5H3CH2C5H3OH)(H2O)][OTf]2 (2), which was further transformed to the complex [Cp?Ir(OC5H3CH2C5H3O)(H2O)] (3) in the presence of t-BuONa via -OH deprotonation. Complexes 1-3 exhibited high activity for the methylation of amines and ketones. These C-C and C-N coupling reactions proceeded in air with 1 mol % catalyst loading in the presence of K2CO3.
- Deng, Danfeng,Hu, Bowen,Yang, Min,Chen, Dafa
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p. 3353 - 3359
(2018/09/25)
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- Efficient and versatile catalytic systems for the n-methylation of primary amines with methanol catalyzed by n-heterocyclic carbene complexes of iridium
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Efficient and versatile catalytic systems were developed for the N-methylation of both aliphatic and aromatic primary amines using methanol as the methylating agent. Iridium complexes bearing an Nheterocyclic carbene (NHC) ligand exhibited high catalytic performance for this type of transformation. For aliphatic amines, selective N,N-dimethylation was achieved at low temperatures (50-90 °C). For aromatic amines, selective N-monomethylation and selective N,N-dimethylation were accomplished by simply changing the reaction conditions (presence or absence of a base with an appropriate catalyst). These findings can be used to develop methods for synthesizing useful amine compounds having N-methyl or N,N-dimethyl moieties.
- Toyooka, Genki,Tuji, Akiko,Fujita, Ken-Ichi
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p. 4617 - 4626
(2019/02/01)
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- Method for selectively preparing N-monomethylamine compound
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The invention discloses a method for selectively preparing an N-monomethylamine compound. The method takes an amine compound, formaldehyde and H2 as reaction raw materials; the raw materials react in a reaction medium in the presence of a compound catalyst at 30 DEG C-180 DEG C for 2h-48h, so as to obtain the N-monomethylamine compound; and the compound catalyst is composed of oxides of at least two of the following metal or oxides of least one of the following metal and at least one metal simple substance: aluminum, copper, nickel, cobalt and iron. According to the method for preparing the N-monomethylamine compound, the conversion ratio and the selectivity of N-monomethylamine are relatively high; the H2 is used as a reducing agent and is clean, cheap and environment-friendly; the catalyst utilized by the method is cheap, simple to prepare and high in catalysis efficiency; and the method has mild preparation and reaction conditions and the catalyst has no corrosiveness, is easy to separate and can be repeatedly used.
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Paragraph 0032-0033
(2017/08/29)
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- N-Methylation of Amines with Methanol Catalyzed by a Cp?Ir Complex Bearing a Functional 2,2′-Bibenzimidazole Ligand
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A new type of Cp?Ir complex bearing a functional 2,2′-bibenzimidazole ligand was designed, synthesized, and found to be a highly effective and general catalyst for the N-methylation of a variety of amines with methanol in the presence of a weak base (0.3 equiv of Cs2CO3).
- Liang, Ran,Li, Shun,Wang, Rongzhou,Lu, Lei,Li, Feng
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supporting information
p. 5790 - 5793
(2017/11/10)
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- METHOD FOR ALKYLATION OF AMINES
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The present invention provides a simple, efficient, and industrially advantageous method for the alkylation of amines. The present invention relates to a production method for N-alkylamines whereby an amine is reacted with an alcohol in the presence of a ruthenium complex represented by general formula (1): RuXY(CO)(L) (wherein X and Y can be the same or different and represent a monovalent anionic ligand, and L represents a tridentate aminodiphosphine ligand).
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Paragraph 0176; 0177
(2016/02/10)
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- Mesoionic pyrido[1,2-a]pyrimidinones: A novel class of insecticides inhibiting nicotinic acetylcholine receptors
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A novel class of mesoionic pyrido[1,2-a]pyrimidinones has been discovered with exceptional insecticidal activity controlling a number of insect species, particularly hemiptera and lepidoptera. Mode-of-action studies showed that they act on nicotinic acetylcholine receptors (nAChRs) primarily as inhibitors. Here we report the discovery, evolution, and preparation of this class of chemistry. Our efforts in structure–activity relationship elucidation and biological activity evaluation are also presented.
- Zhang, Wenming,Holyoke, Caleb W.,Barry, James,Leighty, Robert M.,Cordova, Daniel,Vincent, Daniel R.,Hughes, Kenneth A.,Tong, My-Hanh T.,McCann, Stephen F.,Xu, Ming,Briddell, Twyla A.,Pahutski, Thomas F.,Lahm, George P.
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p. 5444 - 5449
(2016/11/11)
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- Room-temperature copper-catalyzed arylation of dimethylamine and methylamine in neat water
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The first room-temperature copper-catalyzed arylations of dimethylamine and methylamine in neat water have been developed. Using a combination of CuI and 6,7-dihydroquinolin-8(5 H)-one oxime as catalyst, dimethylamine is arylated with various aryl halides to give the corresponding products in good to excellent yields. Further, this catalysis enables the selective arylation of methylamine to afford the high yields of monoarylated methylamines as the sole products.
- Wang, Deping,Kuang, Daizhi,Zhang, Fuxing,Yang, Chunlin,Zhu, Xiaoming
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supporting information
p. 714 - 718
(2015/03/18)
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- Chloroformate free, scalable approach for the synthesis of organic carbamates and their alkylation
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A convenient method for the synthesis of organic carbamates of 2-aminopyridine without using hazardous chloroformate reagent is developed. This alternate approach for the synthesis of organic carbamates and their alkylation to 2-alkylaminopyridines is more practical and economical to be used on large scale. The amazing behavior of 2- aminopyridine helps in forming organic carbamates unlike 3-aminopyridine and 4-aminopyridine.
- Shewalkar, Mukesh P.,Rao, Ramakrishna R.,Reddy, Veerbhadra,Darandale, Sunil N.,Shinde, Devanand B.
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- Iridium- and rhodium-catalyzed dehydrogenative silylations of C(sp 3) - H bonds adjacent to a nitrogen atom using hydrosilanes
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Now that is just silylated: In the presence of iridium or rhodium catalysts, C(sp3) - H bonds adjacent to a nitrogen atom were silylated by the aid of a pyridine-directing group. In iridium catalysis, a hydrogen-trapping reagent such as norbornene or tert-butylethylene, which is usually required in late transition-metal-catalyzed dehydrogenative coupling reactions, was not required. In rhodium catalysis, however, 1 equivalent of COD (1,5-cyclooctadiene) was necessary to induce higher conversion. Copyright
- Mita, Tsuyoshi,Michigami, Kenichi,Sato, Yoshihiro
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p. 2970 - 2973
(2014/01/06)
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- NOVEL CATALYSTS
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The present invention provides novel compounds and ligands that are useful in transition metal catalyzed cross-coupling reactions. For example, the compounds and ligands of the present invention are useful in palladium or gold catalyzed cross-coupling reactions.
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Page/Page column 66
(2012/06/01)
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- General and efficient method for direct N-monomethylation of aromatic primary amines with methanol
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The direct N-monomethylation of aromatic primary amines, including arylamines, arylsulfonamides and amino-azoles, using methanol as a methylating agent has been accomplished in the presence of a [CpIrCl2]2/NaOH system. From both synthetic and environmental points of view, the reaction is highly attractive because of low catalyst loading, broad substrate scope and excellent selectivities.
- Li, Feng,Xie, Jianjiang,Shan, Haixia,Sun, Chunlou,Chen, Lin
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p. 8645 - 8652
(2015/03/05)
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- A facile N-monoalkylation of aminopyridines
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The N-monoalkylation of 2- or 3-aminopyridines by a carboxylic acid and sodium borohydride afforded the corresponding alkylaminopyridine under mild conditions in good yields. N-Alkylaminopyridines are important intermediate for preparing N-containing heterocycles, such as flytrap aminopyridinium-based anion hosts and pharmaceuticals.
- Tian, Zhongzhen,Li, Dongmei,Jiang, Zhaoxing,Li, Zhong
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p. 628 - 629,2
(2020/07/30)
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- Nickel-catalyzed intermolecular codimerization of acrylates and alkynes
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The linear codimerization of acrylates and alkynes to produce 1,3-dienes is successfully demonstrated using a nickel catalyst in association with 2-aminopyridine as an additive.
- Horie, Hiroaki,Koyama, Ichiro,Kurahashi, Takuya,Matsubara, Seijiro
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supporting information; experimental part
p. 2658 - 2660
(2011/05/03)
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- General and mild preparation of 2-aminopyridines
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A general and facile one-pot amination procedure for the synthesis of 2-aminopyridines from the corresponding pyridine-N-oxides is presented as a mild alternative to SNAr chemistry. A variety of amines and heterocyclic-N-oxides participate effectively in this transformation which uses the phosphonium salt, PyBroP, as a means of substrate activation.
- Londregan, Allyn T.,Jennings, Sandra,Wei, Liuqing
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supporting information; experimental part
p. 5254 - 5257
(2011/02/24)
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- A highly versatile catalyst system for the cross-coupling of aryl chlorides and Amines
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The syntheses of 2-(di-tertbutylphosphino)-N,N-dimethylaniline (L1, 71%) and 2-(di-1-adamantylphosphino)-N,N-dimethylaniline (L2, 74%), and their application in BuchwaldHartwig amination, are reported. In combination with [Pd(allyl)Cl]2 or [Pd(cinnamyl)Cl]2, these structurally simple and air-stable P,N ligands enable the cross-coupling of aryl and heteroaryl chlorides, including those bearing as substituents enolizable ketones, ethers, esters, carboxylic acids, phenols, alcohols, olefins, amides, and halogens, to a diverse range of amine and related substrates that includes primary alkyl- and arylamines, cyclic and acyclic secondary amines, N-H imines, hydrazones, lithium amide, and ammonia. In many cases, the reactions can be performed at low catalyst loadings (0.5-0.02 mol % Pd) with excellent functional group tolerance and chemoselectivity. Examples of cross-coupling reactions involving 1,4-bromochlorobenzene and iodobenzene are also reported. Under similar conditions, inferior catalytic performance was achieved when using Pd(OAc)2, PdCl2, [PdCl2(cod)] (cod = 1,5-cyclooctadiene), [PdCl 2(MeCN)2], or [Pd2(dba)3] (dba = dibenzylideneacetone) in combination with L1 or L2, or by use of [Pd(allyl)Cl]2 or [Pd(cinnamyl)Cl]2 with variants of L1 and L2 bearing less basic or less sterically demanding substituents on phosphorus or lacking an ortto-dimethylamino fragment. Given current limitations associated with established ligand classes with regard to maintaining high activity across the diverse possible range of C-N coupling applications, L1 and L2 represent unusually versatile ligand systems for the cross-coupling of aryl chlorides and amines
- Lundgren, Rylan J.,Sappong-Kumankumah, Antonia,Stradiotto, Mark
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supporting information; experimental part
p. 1983 - 1991
(2010/07/03)
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- Chemistry of aryl n -(2-pyridyi) thionocarbamates in basic media
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Three aryl A/-pyridylthionocarbamates were synthesized by thioacylation of 2-aminopyridine and 2-methylaminopyridine with the respective chlorothionoformates. Their hydrolysis mechanism was studied in aqueous basic media. The aryl A/-(2-pyridyl)thionocarb
- Silva, Daniel,Norberto, Fatima,Santos, Susana,Herves, Pablo
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experimental part
p. 221 - 228
(2010/04/04)
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- An efficient method for the selective iridium-catalyzed monoalkylation of (hetero)aromatic amines with primary alcohols
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An efficient multi-gram scale synthesis protocol of a variety of P,N ligands is described. The synthesis is achieved in a two-step reaction. First, the amine is deprotonated and subsequently the chlorophosphine is added to yield the corresponding P,N ligand. Deprotonation of the amine is normally achieved with n-BuLi at low temperature, but for the preparation of ligands with a 2,2′-dipyridylamino backbone and phosphines with a high steric demand KH has to be employed in combination with reaction temperatures of 110°C for the salt metathesis step. The reaction of two equivalents of a selected P,N ligand with one equivalent of the iridium complex [IrCl(cod)]2 (cod=1,5-cyclooctadiene) affords P,N ligand-coordinated iridium complexes in quantitative yield. X-Ray single crystal structure analysis of one of these complexes reveals a monomeric five-coordinated structure in the solid state. The iridium complexes were used to form catalysts for the N-alkylation of aromatic amines with alcohols. The catalyst system was optimized by studying 8 different P,N ligands, 9 different solvents and 14 different bases. Systematic variation of the substrate to base and the amine to alcohol ratios as well as the catalyst loading led to optimized catalytic reaction conditions. The substrate scope of the developed catalytic protocol was shown by synthesizing 20 different amines of which 12 could be obtained in isolated yields higher than 90%. A new efficient catalyst system for the selective monoalkylation of primary aromatic and heteroaromatic amines with primary aromatic, heteroaromatic as well as aliphatic alcohols has been established. The reaction proceeds with rather moderate catalyst loadings.
- Blank, Benoit,Madalska, Martyna,Kempe, Rhett
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supporting information; scheme or table
p. 749 - 758
(2009/04/10)
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- Role of copper in catalyzing aryl and heteroaryl-nitrogen (or -oxygen) bond formation under ligand-free and solvent-free conditions
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Formation of aryl- or heteroaryl-nitrogen (or -oxygen) bonds under ligand and solvent-free conditions are highly selective to the presence of copper. While bromoarenes undergo C-N (or -O) coupling in stoichiometric presence of copper, heteroaryl bromides require only catalytic amounts of copper(I) salts depending on the position of bromo substituents. Such selectivity coupled with ligand and solvent-free protocols appear promising from the viewpoint of ecology and economy and are more attractive as compared to the existing protocols.
- Basu, Basudeb,Das, Sajal,Mandal, Bablee
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experimental part
p. 1701 - 1706
(2009/07/04)
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- Identification of novel PPARα ligands by the structural modification of a PPARγ ligand
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To develop novel PPARα ligands, we designed and synthesized several 3-{3-[2-(nonylpyridin-2-ylamino)ethoxy]phenyl}propanoic acid derivatives. Compound 10, the meta isomer of a PPARγ agonist 1, has been identified as a PPARα ligand. The introduction of methyl and ethyl groups at the C-2 position of the propanoic acid of 10 further improved the PPARα-binding potency.
- Usui, Shinya,Fujieda, Hiroki,Suzuki, Takayoshi,Yoshida, Naoaki,Nakagawa, Hidehiko,Miyata, Naoki
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p. 3249 - 3254
(2007/10/03)
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- The titanocene-catalyzed reduction of acetamides to tertiary amines by PhMeSiH2
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A variety of acetamide derivatives are reduced in excellent yields to tertiary amines by PhMeSiH2 in the presence of Cp2TiX 2 (X = F or Me) catalysts. The reactions are very clean at 80 °C. At room temperature a secondary reaction, hydrogenolysis of the C(O)-N bond, intervenes and reduces the chemoselectivity. Nevertheless, this chemistry provides a simple methodology for the amide/alkylamine transformation using inexpensive, commercially available reagents.
- Selvakumar, Kumaravel,Rangareddy, Kesamreddy,Harrod, John F.
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p. 1244 - 1248
(2007/10/03)
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- A convenient synthesis of 2-(alkylamino)pyridines
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The synthesis of a series of 2-(alkylamino) pyridines (1) in three steps from 2-aminopyridine (4) is reported. The products were obtained in 67-91% overal yield from 4.
- Krein, Douglas M.,Lowary, Todd L.
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p. 4965 - 4967
(2007/10/03)
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- Reactivity of N-pyridylcarbamates in basic media
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New secondary aryl N-pyridylcarbamates were prepared by reaction of the aminopyridine anion with aryl chloroformates and their hydrolysis was studied over the pH range from 12 to 13.7. The pH-rate profile points to an E1cB mechanism, involving pre-equilibrium deprotonation of the nitrogen atom to form an anion that undergoes rate-limiting decomposition into pyridyl isocyanate and a phenoxide ion. Further reaction of the highly reactive isocyanate with water affords N-pyridylcarbamic acid, which spontaneously decomposes to aminopyridine and carbon dioxide. The absence of significant base catalysis and the isolation of a new product resulting from trapping of the intermediate with the base piperidine are also consistent with an elimination addition mechanism. Finally the observed substituent effect (σ-) gives ρ 2.45 which is in accordance with a rate-determining departure of the phenoxide group from the anion intermediate formed in a pre-equilibrium step. Blocking the E1cb mechanism of the secondary carbamates by introduction of N,N-disubstitution in the substrate led to a rate-limiting decrease of ca. 106.
- Norberto, Fatima,Santos, Susana,Silva, Daniel,Herves, Pablo,Miguel, Ana Sofia,Vilela, Filipe
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p. 1162 - 1165
(2007/10/03)
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- Reductive monoalkylation of aromatic amines via amidine intermediates
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The convenience and efficiency of using amidines as intermediates in the reductive monoalkylation of aromatic amines has been demonstrated. This monoalkylation can be performed as either a two-step synthesis or a one-pot procedure. Several examples are presented which clearly demonstrate the utility of this new method for the methylation or ethylation of aromatic amines, including unprotected nucleosides.
- Zhang, Jianxing,Chang, Hui-Min,Kane, Robert R.
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p. 643 - 645
(2007/10/03)
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- Pyridinium N-,(2'-azinyl)aminides: Regioselective synthesis of 2- alkylaminoazines
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The regioselective alkylation of pyridinium-N-(2f'-azinil)aminides with alkyl halides under mild conditions is described. The alkylation, combined with a reduction of the N-N bond, allows an easy preparation of 2- alkylaminoazines. (C) 2000 Elsevier Science Ltd.
- Martínez-Barrasa, Valentín,Delgado, Francisca,Burgos, Carolina,Luis García-Navío,Luisa Izquierdo,Alvarez-Builla, Julio
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p. 2481 - 2490
(2007/10/03)
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- Mesoions and ketene valence isomers. Three types of rearrangement of mesoionic pyridopyrimidinylium olates involving ketene intermediates
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The ketene valence isomers of mesoionic pyrimidinylium olates undergo (i) a retro-ene type fragmentation to C3O2 16 and 2-aminopyridine 15, (ii) an electrocyclisation to form a naphthyridine (19→20→21), or (iii) a cycloreversion to 2-pyridyl isocyanate 26 and a ketene 25.
- Fiksdahl, Anne,Plueg, Carsten,Wentrup, Curt
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p. 1841 - 1845
(2007/10/03)
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- (2-Pyridyl)iminopropadienone
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(2-Pyridyl)iminopropadienone 13 is generated by flash vacuum thermolysis (FVT) of 2-substituted pyrido[1,2-a]pyrimidin-4-ones 9 and observed by IR spectroscopy. Addition of HCl to 13 causes reversion to the starting material 9b, whereas addition of nucleophiles leads to malonic acid imide derivatives (23, 24, 26, 27, 28). The latter undergo thermal elimination of amines to regenerate 2-substituted pyridopyrimidinones. A competing retro-ene reaction occurs on FVT of 2-(dialkylamino)pyridopyrimidinones 9c,d, presumably in the oxoketenimine intermediates 22/25, with formation of the unsubstituted pyridopyrimidinone 31.
- Plueg, Carsten,Frank, Wilhelm,Wentrup, Curt
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p. 1087 - 1094
(2007/10/03)
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- Ruthenium complex-controlled catalytic N-mono- or N,N-dialkylation of heteroaromatic amines with alcohols
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Heteroaromatic amines were N-alkylated with primary alcohols at 150-200°C in the presence of a catalytic amount of various ruthenium complexes to give the corresponding monoalkylated and dialkylated amines in good to high yields. For example, 2-aminopyridine reacted with an excess of ethanol at 180°C for 20 h in the presence of dichlorotris(triphenylphosphine)ruthenium [RuCl2-(PPh3)3] to give 2-(ethylamino)pyridine (1) and 2-(diethylamino)pyridine (2) in 9% and 70% yields, respectively. On the other hand, when (η4-1,5-cyclooctadiene)(η 6-1,3,5-cyclooctatriene)ruthenium [Ru(cod)(cot)] was used as a catalyst, even in the presence of excess ethanol, 1 was obtained in 85% yield with high selectivity. The addition of tertiary phosphines and phosphites to Ru(cod)-(cot) increased the yield of the dialkylated amine.
- Watanabe, Yoshihisa,Morisaki, Yasuhiro,Kondo, Teruyuki,Mitsudo, Take-Aki
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p. 4214 - 4218
(2007/10/03)
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- 1H-INDAZOLES AS SYNTHETIC AUXILIARIES FOR THE SYNTHESIS OF SECONDARY AROMATIC AMINES
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Methodology of alkylation of aromatic amines using 1H-indazoles as synthetic auxiliares is reported.
- Saladino, Raffaele,Crestini, Claudia,Nicoletti, Rosario
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p. 567 - 574
(2007/10/02)
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- Pyridinium-N-(2-pyridyl)aminides: A selective approach to substituted 2-aminopyridines
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Differently substituted 2-aminopyridines have been prepared in two steps from pyridinium-N-(2-pyridyl)aminide.
- Carceller, Rosa,Garcia-Navio, Jose L.,Izquierdo, Maria L.,Alvarez-Builla, Julio
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p. 2019 - 2020
(2007/10/02)
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- The Chemistry of N-Substituted Benzotriazoles. Part 4. A Novel and Versatile Method for the Mono-N-alkylation of Aromatic and Heteroaromatic Amines
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Mono-N-alkylation of aromatic and heteroaromatic amines is achieved in high yield by NaBH4 reduction of the adducts formed from benzotriazole, aliphatic aldehydes and the amines.Reaction of the same adducts with Grignard reagents gives N-(secondary alkyl)arylamines.Carboxy groups need no protection and nitro groups are unaffected.Adenine is mono-N-alkylated in high yield.
- Katritzky, Alan R.,Rachwal, Stanislaw,Rachwal, Bogumila
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p. 805 - 810
(2007/10/02)
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- ASYMMETRIC REDUCTION OF PROCHIRAL CYCLIC KETONES WITH LITHIUM ALUMINIUM HYDRIDE PARTIALLY DECOMPOSED BY (1R,2S)-(-)-N-METHYLEPHEDRINE AND 2-ALKYLAMINOPYRIDINE
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The title chiral hydride was found to reduce prochiral cyclic ketones, affording the corresponding optically active cyclic alcohols in high optical (max. 98percentee) yields.
- Kawasaki, Motoji,Suzuki, Yasutaka,Terashima, Shiro
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p. 239 - 242
(2007/10/02)
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- A Very Long Cobalt to Nitrogen Bond in a Coenzyme B12 Model. Relevance to the Role of the 5,6-Dimethylbenzimidazole in C0-C Bond Cleavage in Coenzyme B12
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The crystal and molecular structure of the complex trans-bis(dimethylglyoximato)isopropyl(2-aminopyridine)cobalt(III) is reported.The compound crystallizes in space group P212121 with a = 27.83 (1) Angstroem, b = 8.564 (6) Angstroem, c = 8.198 (6) Angstroem, V = 1958.1 Angstroem3, Dm = 1.45 g cm-3, Z = 4, and Dc = 1.45 g cm-3.A total of 2740 reflections were measured.The structure was solved with conventional Patterson and Fourier methods.Block-diagonal least-squares refinement led to a final R value of 0.033.The complex is pseudooctahedral with the dimethylglyoximato ligands occupying the four equatorial positions and the isopropyl ligand occupying one of the axial positions.The geometry of these ligands and their relationship to Co are very similar to those of the known pyridine analogue.However, the bond from Co to the endocyclic N of 2-aminopyridine is unusually long, namely 2.194 (4) Angstroem.This long bond is believed to result from repulsion between the 2-amino group and the equatorial ligands.Another consequence of this interaction is the unsymmetrical nature of the Co-N-C angles, which are 129.7 (4) deg for the 2-carbon and 115.7 (3) deg for the 6-carbon.This angular distortion and the long Co-N bond are also found in coenzyme B12.Rate studies with trans-alkylbis(dimethylglyoximato)(L)cobalt(III), in which 2-aminopyridine analogues (L) are exchanged by stronger ligands such as P(OCH3)3, can best be interpreted by the endocyclic binding mode of 2-aminopyridine in solution.In conjunction with literature on Co-C bond energies of related B12 models, the potential influence of the 5,6-dimethylbenzimidazole ligand in Co-C bond cleavage in coenzyme B12 dependent reactions is discussed.
- Summers, Michael F.,Toscano, Paul J.,Bresciani-Pahor, Nevenka,Nardin, Giorgio,Randaccio, Lucio,Marzilli, Luigi G.
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p. 6259 - 6263
(2007/10/02)
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- Sodium Borohydride Reduction of Adducts of Primary Amines with Aldehydes and p-Thiocresol. The Alkylation of Heterocyclic and Aromatic Amino-compounds
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p-Nitroaniline, 2-aminopyridine (1a), 4-aminopyridine (2a), 2-amino-4-methylpyrimidine (8a), 2-aminothiazole (10a), and 2-aminobenzimidazole (12a) react with aqueous formaldehyde and p-thiocresol in ethanol or methanol solution to give N-(p-tolylthiomethyl) derivatives , usually in high yields.When the latter compounds are heated, under reflux, with an excess of sodium borohydride in ethanol or 1,2-dimethoxyethane solution, the corresponding methylamino-compounds are obtained.By a similar two-step prosedure in which aqueous formaldehyde is replaced, as appropriate, by anhydrous acetaldehyde, propionaldehyde, or benzaldehyde, p-nitroaniline is converted into N-ethyl-p-nitroaniline, p-chloroaniline is converted into p-chloro-N-(n-propyl)aniline, (1a) is converted into the corresponding ethylamino- and benzylamino-compounds (1c) and (1d), respectively, and (10a) and (12a) are converted into their 2-N-(n-propyl) derivatives (10c) and (12c), respectively.
- Kemal, Oeznur,Reese, Colin B.
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p. 1569 - 1573
(2007/10/02)
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- Reactions of N-Heteroaromatic Bases with Nitrous Acid. Part 6. Kinetics of the Nitrosation of 2- and 4-Methylaminpprridine and their 1-Oxide Derivates
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The nitrosation of 2- and 4-methylaminopyridine and their 1-oxide derivates in 0.002-5.00 M-perchoric acid is of first order in a both the amine and nitrous acid.The respective nitrosamines formed are easily denitrosated under the experimental conditions.The rate coefficients of the nitrosation increase with an increase in the concenration of perchloric acid and sodium perchlorate.In perchloric acid solution whose ionic strength is maintained constant by the addition of sodium perchlorate the rate coefficients of the nitrosation of 2- and 4-methylaminopyridine only show rectilinear dependence on the h0 parameter of the medium.The nitrosation of 2- and 4-methylaminopyridine proceeds mainly by the interaction of the nitrous acidium ion with the protonated form of these amines whilst the nitrosation of 2- and 4-methylaminopyridine 1-oxide proceeds by the simultaneous interaction of the nitrous acidium ion with the protonated and the free form of both amines.The nitrous acidium ion seems to show a distinct discrimination in its reaction with free form of the amines as evidenced by a rectilinear relationship between the rate coefficient of ther nitrosation and their Ka values.The protonated amine 1-oxides react faster than the protonated amines when the hydroxy-group is in para-position with respect to the amino-group and therefore not involved in hydrogen bonding with it.The nitrosation of free and the protonated amines involves an initial interaction between the nitrosating agent and the heteroaromatic nucleus.The present results show that the formation of the respective N-nitroso-derivate is the rate-determining stage of the diazotisation of the N-heteroaromatic amines over the whole of the acid range examined. pKa Values are recorded.
- Kalatzis, Evangelos,Papadopoulos, Panayiotis
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p. 239 - 247
(2007/10/02)
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- A ONE POT SYNTHESIS OF UNSYMMETRICAL SECONDARY ALCOHOLS FROM TWO GRIGNARD REAGENTS
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The sequential addition of two Grignard reagents to 2-(N-methyl-N-formyl)-amino-pyridine in tetrahydrofuran provides a high yield one pot synthesis of unsymmetrical secondary alcohols.
- Comins, Daniel L.,Dernell, William
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p. 1085 - 1088
(2007/10/02)
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- Benzenesulfonyl-ureas
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Sulfonyl-ureas of the formula STR1 wherein X represents a heteroaromatic 5- or 6-ring substituted, if desired, by one or two methyl groups and/or annellated with benzene, which ring may contain in addition to a nitrogen atom a further nitrogen, oxygen or sulfur atom and which, in vicinal position to the nitrogen atom, is linked to the rest of the molecule portion, R is alkyl having 1 to 3 carbon atoms, R1 is alkyl having 3 to 6 carbon atoms, cycloalkyl, alkylcycloalkyl, cycloalkylalkyl, cycloalkenyl, alkylcycloalkenyl having each 5 to 9 carbon atoms, cyclohexenylmethyl, chlorocyclohexyl, bicycloheptenylmethyl, bicycloheptylmethyl, bicycloheptenyl, bicycloheptyl, nortricyclyl, adamantyl, benzyl, which as substance or in form of the salts thereof have hypoglycemic properties and are distinguished by a strong and continuous lowering of the blood sugar level, process for preparing them as well as pharmaceutical preparations containing the sulfonyl-ureas as an active substance.
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