- Organic photoredox catalytic α-C(sp3)-H phosphorylation of saturated: Aza -heterocycles
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A metal-free C(sp3)-H phosphorylation of saturated aza-heterocycles via the merger of organic photoredox and Br?nsted acid catalyses was established under mild conditions. This protocol provided straightforward and economic access to a variety of valuable α-phosphoryl cyclic amines by using commercially available diarylphosphine oxide reagents. In addition, the D-A fluorescent molecule DCQ was used for the first time as a photocatalyst and exhibited an excellent photoredox catalytic efficiency in this transformation. A series of mechanistic experiments and DFT calculations demonstrated that this transformation underwent a sequential visible light photoredox catalytic oxidation/nucleophilic addition process.
- Yi, Ming-Jun,Xiao, Teng-Fei,Li, Wen-Hui,Zhang, Yi-Fan,Yan, Pen-Ji,Zhang, Baoxin,Xu, Peng-Fei,Xu, Guo-Qiang
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supporting information
p. 13158 - 13161
(2021/12/16)
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- Mild reduction with silanes and reductive amination of levulinic acid using a simple manganese catalyst
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A manganese-based catalytic system using the commercially available complex [Mn(CO)5Br] was studied for the selective reduction of levulinic acid (LA) to 2-methyl-tetrahydrofuran (MTHF). We further studied the production of pyrrolidines via its reductive amination using silanes (phenylsilane and tetramethyldisiloxane). The results showed high efficiency and selectivity for this reaction leading to high yields using mild reaction conditions.
- Garcia, Juventino J.,Roa, Diego A.
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- Investigation towards the reductive amination of levulinic acid by B(C6F5)3/hydrosilane system
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The selective transformation of the renewable biomass resources into the highly value-added platform chemicals is essentially important for sustainable chemistry. Here we report a simple and highly efficient strategy for the synthesis of N-heterocyclic co
- He, Jianghua,Wang, Tianlong,Xu, Hai,Zhang, Yuetao
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- Practical direct synthesis of: N -aryl-substituted azacycles from N -alkyl protected arylamines using TiCl4and DBU
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A novel transformation of N-alkyl protected arylamines and cyclic ethers into N-aryl substituted azacycles is described. Alkyl groups have been used for the protection of amines in organic syntheses. In this synthesis, N-alkyl protected arylamines were reacted with cyclic ethers in the presence of TiCl4 and DBU, crucial reagents affording five- and six-membered azacycles. In particular, utilization of the novel TiCl4/DBU-mediated reaction allows various N-alkyl protected arylamines such as N-methyl-, N-ethyl-, N-isopropyl, and N-tert-butyl arylamines to be readily converted into N-aryl substituted azacycles in high yields. This practical approach using various N-alkyl arylamines leads to the efficient preparation of azacycles.
- Kang, Soosung,Kim, Hee-Kwon,La, Minh Thanh,Tran, Van Hieu
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p. 5008 - 5016
(2020/07/30)
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- Iron-Catalysed Switchable Synthesis of Pyrrolidines vs Pyrrolidinones by Reductive Amination of Levulinic Acid Derivatives via Hydrosilylation
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A selective production of pyrrolidines vs pyrrolidinones via hydrosilylation of levulinic acid and levulinates by switching of the iron complex catalyst is presented herein. The reactions proceeded efficiently with various anilines and alkylamines under both visible light irradiation and thermal conditions with 43 examples in isolated yields up to 93%. Noticeably, under similar conditions, cyclic amines such as piperidines and azepanes were efficiently synthesized with yields up to 92%, by reaction of anilines with 1,5- or 1,6-keto acids, respectively. Similarly, N-arylinsolidoline compounds can be prepared from 2-formylbenzoic acid in 57–93% yields. (Figure presented.).
- Wei, Duo,Netkaew, Chakkrit,Darcel, Christophe
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supporting information
p. 1781 - 1786
(2019/02/26)
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- Metal-Free Synthesis of N-Aryl-Substituted Azacycles from Cyclic Ethers Using POCl3
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A facile method for the synthesis of N-aryl-substituted azacycles from arylamines and cyclic ethers has been developed. In this study, arylamines were treated with cyclic ethers in the presence of POCl3 and DBU to provide five- A nd six-membered azacycles. Using this method, various azacycloalkanes, isoindolines, and tetrahydroisoquinolines were prepared in high yields. This synthetic method offers an efficient approach to the production of azacycles from cyclic ethers.
- La, Minh Thanh,Kang, Soosung,Kim, Hee-Kwon
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p. 6689 - 6696
(2019/06/14)
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- Phosphoryl chloride-mediated solvent-free synthesis of N-aryl-substituted azacycles from arylamines and cyclic ethers
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A solvent- and metal-free protocol for preparation of N-aryl substituted azacycles from arylamines and cyclic ethers is described. In this method, the combination of POCl3 and DBU is crucial for conversion of arylamines and cyclic ethers to five- and six-membered azacycles. Without solvent, a variety of N-aryl-substituted, five-membered azacycles (pyrrolidines, 2-methylpyrrolidines, and piperidine) and six-membered azacycles (isoindolines and tetrahydroisoquinolines) are synthesized in high yields. This green method provides a sustainable and efficient approach for the preparation of azacycles from various cyclic ethers.
- Tran, Van Hieu,La, Minh Thanh,Kim, Hee-Kwon
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supporting information
p. 1860 - 1863
(2019/06/19)
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- Practical and regioselective amination of arenes using alkyl amines
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The formation of carbon–nitrogen bonds for the preparation of aromatic amines is among the top five reactions carried out globally for the production of high-value materials, ranging from from bulk chemicals to pharmaceuticals and polymers. As a result of this ubiquity and diversity, methods for their preparation impact the full spectrum of chemical syntheses in academia and industry. In general, these molecules are assembled through the stepwise introduction of a reactivity handle in place of an aromatic C–H bond (that is, a nitro group, halogen or boronic acid) and a subsequent functionalization or cross-coupling. Here we show that aromatic amines can be constructed by direct reaction of arenes and alkyl amines using photocatalysis, without the need for pre-functionalization. The process enables the easy preparation of advanced building blocks, tolerates a broad range of functionalities, and multigram scale can be achieved via a batch-to-flow protocol. The merit of this strategy as a late-stage functionalization platform has been demonstrated by the modification of several drugs, agrochemicals, peptides, chiral catalysts, polymers and organometallic complexes.
- Ruffoni, Alessandro,Juliá, Fabio,Svejstrup, Thomas D.,McMillan, Alastair J.,Douglas, James J.,Leonori, Daniele
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p. 426 - 433
(2019/05/01)
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- Dual C(sp3)?H Bond Functionalization of N-Heterocycles through Sequential Visible-Light Photocatalyzed Dehydrogenation/[2+2] Cycloaddition Reactions
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Herein we describe a mild method for the dual C(sp3)?H bond functionalization of saturated nitrogen-containing heterocycles through a sequential visible-light photocatalyzed dehydrogenation/[2+2] cycloaddition procedure. As a complementary approach to the well-established use of iminium ion and α-amino radical intermediates, the elusive cyclic enamine intermediates were effectively generated by photoredox catalysis under mild conditions and efficiently captured by acetylene esters to form a wide array of bicyclic amino acid derivatives, thus enabling the simultaneous functionalization of two vicinal C(sp3)?H bonds.
- Xu, Guo-Qiang,Xu, Ji-Tao,Feng, Zhi-Tao,Liang, Hui,Wang, Zhu-Yin,Qin, Yong,Xu, Peng-Fei
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supporting information
p. 5110 - 5114
(2018/03/27)
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- Transition-Metal-Free Selective C?H Benzylation of Tertiary Arylamines by a Dearomatization-Aromatization Sequence
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Due to the significance of hybrid systems in drug discovery, there is an urgent need to assemble multiple biologically active ingredients into a single molecule. Here, we report a general transition-metal-free selective C?H benzylation of tertiary arylamines in good to excellent yields with a broad substrate scope and high functional-group tolerance under mild conditions. Besides arylamines, some other benzene derivatives also readily furnished the corresponding diaryl methane derivatives with this protocol. A series of control experiments and theoretical calculations indicated that this transition-metal-free reaction is a dearomatization-aromatization process.
- Xu, Guo-Qiang,Feng, Zhi-Tao,Xu, Ji-Tao,Wang, Zhu-Yin,Qin, Yong,Xu, Peng-Fei
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supporting information
p. 13778 - 13782
(2018/09/14)
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- Noble metal-free upgrading of multi-unsaturated biomass derivatives at room temperature: Silyl species enable reactivity
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Biomass derivatives are a class of oxygen-rich organic compounds, which can be selectively upgraded to various value-added molecules by partial or complete hydrogenation over metal catalysts. Here, we show that Cs2CO3, a low-cost commercial chemical, enables the selective reduction of dicarbonyl compounds including bio-derived carboxides to monohydric esters/amides, hydroxylamines or diols with high yields (82-99%) at room temperature using eco-friendly and equivalent hydrosilane as a hydride donor. The in situ formation of silyl ether enables the developed catalytic system to tolerate other unsaturated groups and permits a wide substrate scope with high selectivities. Spectroscopic and computational studies elucidate reaction pathways with an emphasis on the role of endogenous siloxane.
- Li, Hu,Zhao, Wenfeng,Dai, Wenshuai,Long, Jingxuan,Watanabe, Masaru,Meier, Sebastian,Saravanamurugan, Shunmugavel,Yang, Song,Riisager, Anders
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p. 5327 - 5335
(2018/12/05)
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- New N-substituted tetrahydropyrrole derivative synthesis method
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The invention provides an amino boron intermediate-mediated synthesis method for preparing N-substituted tetrahydropyrrole derivatives by using aromatic amine and a five-membered oxygen heterocyclic compound as raw materials. According to the present invention, the N-substituted tetrahydropyrrole derivatives are specifically N-aryltetrahydropyrrole and N-aryl 2-methyltetrahydropyrrole, and have the following chemical structure general formulas, wherein Ar is phenyl, 4-methylphenyl, 4-fluorophenyl, 4-chlorophenyl, 2-chlorophenyl, 3-nitrophenyl, 2,4-difluorophenyl, 2,6-dichlorophenyl or 3,5-dichlorophenyl. The present invention discloses the chemical structures and the synthesis method of the compounds.
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-
Paragraph 0032-0033
(2019/11/13)
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- Reductive amination/cyclization of levulinic acid to pyrrolidones: Versus pyrrolidines by switching the catalyst from AlCl3 to RuCl3 under mild conditions
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Herein the reductive amination/cyclization of levulinic acid using phenylsilane was presented to selectively produce pyrrolidones versus pyrrolidines under mild conditions by switching the catalyst from AlCl3 to RuCl3. Using AlCl3 as the catalyst, pyrrolidones were solely obtained at room temperature, while RuCl3 as the catalyst selectively afforded pyrrolidines in high yields at 45 °C.
- Liu, Zhimin,Wu, Cailing,Luo, Xiaoying,Zhang, Hongye,Liu, Xinwei,Ji, Guipeng,Liu, Zhenghui
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supporting information
p. 3525 - 3529
(2017/08/15)
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- Synthetic method for five-component and six-component N-substituted nitrogenous heterocyclic compounds
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The invention provides a synthetic method for preparing five-component and six-component N-substituted nitrogenous heterocyclic compounds from aromatic amine and five-component and six-component oxygen heterocyclic compounds via mediation by an aminotitanium intermediate. The five-component and six-component N-substituted nitrogenous heterocyclic compounds provided by the invention specifically refer to N-aryltetrahydropyrrole, N-aryl-2-methyltetrahydropyrrole, N-aryltetrahydropyrane, N-aryl-3,4-dihydro-1H-2-pyrane with a general chemical formula as defined in the specification. In the formula, Ar is a phenyl group, a 4-methylphenyl group, a 2-halophenyl group, a 3-halophenyl group or a 4-halophenyl group. The invention discloses the chemical structures and synthetic method of the compounds.
- -
-
Paragraph 0026; 0027
(2017/02/09)
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- Titanium tetrachloride-mediated synthesis of N-aryl-substituted azacycles from cyclic ethers
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Titanium tetrachloride-mediated transformation of five- and six-membered cyclic ethers to the corresponding N-aryl-substituted azacycles is conducted in moderate to good yields under mild reaction conditions. Computational studies suggested a mechanism involving a Lewis acid-assisted ring-opening, a seven-membered metallacycle intermediate and a ring-closing process facilitated by direct participation of the metal center.
- Sun, Zunming,Hu, Shanshan,Huo, Yan,Wang, Zhihong
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p. 4363 - 4367
(2017/01/29)
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- Direct Acylation of C(sp3)-H Bonds Enabled by Nickel and Photoredox Catalysis
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Using nickel and photoredox catalysis, the direct functionalization of C(sp3)-H bonds of N-aryl amines by acyl electrophiles is described. The method affords a diverse range of α-amino ketones at room temperature and is amenable to late-stage coupling of complex and biologically relevant groups. C(sp3)-H activation occurs by photoredox-mediated oxidation to generate α-amino radicals which are intercepted by nickel in catalytic C(sp3)-C coupling. The merger of these two modes of catalysis leverages nickel's unique properties in alkyl cross-coupling while avoiding limitations commonly associated with transition-metal-mediated C(sp3)-H activation, including requirements for chelating directing groups and high reaction temperatures. Teamwork: The direct functionalization of C(sp3)-H bonds of N-aryl amines by acyl electrophiles is achieved, thus affording a diverse range of α-amino ketones at room temperature. C(sp3)-H activation occurs by photoredox-mediated oxidation to generate α-amino radicals which are intercepted by nickel in catalytic C(sp3)-C coupling.
- Joe, Candice L.,Doyle, Abigail G.
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supporting information
p. 4040 - 4043
(2016/03/19)
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- Dichotomy of reductive addition of amines to cyclopropyl ketones vs pyrrolidine synthesis
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An interesting catalytic dichotomy was discovered: switching between simple ligand-free catalysts leads to fundamentally different outcomes of reductive reaction between amines and α-carbonylcyclopropanes. Whereas a rhodium catalyst leads to the tradition
- Afanasyev, Oleg I.,Tsygankov, Alexey A.,Usanov, Dmitry L.,Chusov, Denis
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supporting information
p. 5968 - 5970
(2016/11/29)
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- Reductive Amination/Cyclization of Keto Acids Using a Hydrosilane for Selective Production of Lactams versus Cyclic Amines by Switching of the Indium Catalyst
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Described herein is that the catalytic construction of N-substituted five- and six-membered lactams from keto acids with primary amines by reductive amination, using an indium/silane combination. This relatively benign and safe catalyst/reductant system tolerates the use of a variety of functional groups, especially ones that are reduction-sensitive. A direct switch from synthesizing lactams to synthesizing cyclic amines is achieved by changing the catalyst from In(OAc)3 to InI3. This conversion occurs by further reduction of the lactam using the indium/silane pair.
- Ogiwara, Yohei,Uchiyama, Takuya,Sakai, Norio
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supporting information
p. 1864 - 1867
(2016/02/03)
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- Stoichiometric and Catalytic Inter- and Intramolecular Hydroamination of Terminal Alkynes by Frustrated Lewis Pairs
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Frustrated Lewis pairs (FLPs) based on sterically encumbered anilines and the Lewis acid B(C6F5)3 were found to react with terminal alkynes effecting intermolecular hydroamination affording iminium alkynylborate species of the form [RPhN-C(R′)Me][R′CCB(C6F5)3]. In these cases, the reagent ratio of borane, aniline, and alkyne is 1:1:2. These reactions could also be performed in an intramolecular fashion by using anilines with alkynyl substituents effecting cyclization reactions. The use of 10mol % B(C6F5)3 under a H2 atmosphere provides a one-pot synthesis of the pyrrolidine 12, the piperidines 13-15, the azepane 16, the isoindoline 17, and the benzoxazine 18. Frustrated but satisfied: B(C6F5)3 was used to effect the stoichiometric and catalytic hydroamination of terminal alkynes by substituted anilines. Both inter- and intramolecular systems were explored in this reactivity. The mechanism adheres to previously observed frustrated Lewis pair reactivity.
- Mahdi, Tayseer,Stephan, Douglas W.
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supporting information
p. 11134 - 11142
(2015/11/10)
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- Automated Serendipity with Self-Optimizing Continuous-Flow Reactors
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A self-optimizing approach is used as a tool for targeting known and unknown materials in the continuous reaction of aniline, dimethyl carbonate (DMC) and tetrahydrofuran (THF) in supercritical CO2 on γ-Al2O3. The study led to the formation of methylated anilines or carbamate derivatives and unusual addition products with THF including pyrrolidines and N-alkylated anilines. The identification of these products leads to the development of a plausible mechanism for the reactions. The system not only demonstrates a high flexibility that the self-optimization approach provides, including the ability to optimize for a variety of products by using a single catalyst, but also the ability to discover unexpected and original synthetic reactions. Self-optimizing continuous-flow reactors have been used to investigate the reaction of aniline with THF and DMC. High-selectivity profiles were obtained for the synthesis of methylated anilines or N-phenylpyrrolidines. By combining the three components in a single reaction system, a tandem alkylation reactivity leading to diversely alkylated anilines was discovered.
- Amara, Zacharias,Streng, Emilia S.,Skilton, Ryan A.,Jin, Jing,George, Michael W.,Poliakoff, Martyn
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p. 6141 - 6145
(2015/10/06)
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- Boron-Catalyzed N-Alkylation of Amines using Carboxylic Acids
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A boron-based catalyst was found to catalyze the straightforward alkylation of amines with readily available carboxylic acids in the presence of silane as the reducing agent. Various types of primary and secondary amines can be smoothly alkylated with good selectivity and good functional-group compatibility. This metal-free amine alkylation was successfully applied to the synthesis of three commercial medicinal compounds, Butenafine, Cinacalcet. and Piribedil, in a one-pot manner without using any metal catalysts.
- Fu, Ming-Chen,Shang, Rui,Cheng, Wan-Min,Fu, Yao
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supporting information
p. 9042 - 9046
(2015/08/03)
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- Synthesis of N-aryl substituted, five- and six-membered azacycles using aluminum-amide complexes
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Synthesis of N-aryl substituted, five- and six-membered azacycloalkanes, isoindolines and tetrahydroisoquinolines, has been described. In this synthesis, cyclic ethers (n = 1, 2) were treated with dimethylaluminum-amide reagents, derived from a range of aryl amines and trimethylaluminum, to afford the corresponding azacycles in good yields. This journal is the Partner Organisations 2014.
- Korbad, Balaji L.,Lee, Sang-Hyeup
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supporting information
p. 8985 - 8988
(2014/08/05)
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- INHIBITORS OF CYSTATHIONINE BETA SYNTHASE TO REDUCE THE NEUROTOXIC OVERPRODUCTION OF ENDOGENOUS HYDROGEN SULFIDE
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The invention is directed to inhibitors of cystathionine beta synthase which, among other biochemical effects, allow reduction of the neurotoxic overproduction of endogenous hydrogen sulphide. These compounds and pharmaceutical compositions containing them are useful for the prevention and treatment of cognitive disorders such as cognitive disorders in Down syndrome. The invention also relates to methods for preventing or treating cognitive disorders including cognitive disorders in Down Syndrome.
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Page/Page column 71-72
(2013/05/23)
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- Aqueous N-heterocyclization of primary amines and hydrazines with dihalides: Microwave-assisted syntheses of N-azacycloalkanes, isoindole, pyrazole, pyrazolidine, and phthalazine derivatives
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The synthesis of nitrogen-containing heterocycles from alkyl dihalides (ditosylates) and primary amines and hydrazines via a simple and efficient cyclocondensation in an alkaline aqueous medium that occurs under microwave irradiation is described. This improved greener synthetic methodology provides a simple and straightforward one-pot approach to the synthesis of a variety of heterocycles, such as substituted azetidines, pyrrolidines, piperidines, azepanes, N-substituted 2,3-dihydro-1H-isoindoles, 4,5-dihydropyrazoles, pyrazolidines, and 1,2-dihydrophthalazines.
- Ju, Yuhong,Varma, Rajender S.
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p. 135 - 141
(2007/10/03)
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- N-phenyl-substituted pyrrolidines, piperidines and azabicyclics by a tandem reduction-double reductive amination reaction
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N-Phenyl-substituted pyrrolidines and piperidines have been synthesized by catalytic reduction of nitrobenzene in the presence of 4- and 5-oxoaldehydes, respectively. The process involves reduction of the aromatic nitro group to give the N-phenylhydroxylamine or aniline followed by reductive amination with the two carbonyl functional groups. Monocyclic systems are generally formed in high yield and are easily purified. The method has also been extended to the synthesis of fused N-phenylazabicyclics from 2-(3-oxopropyl)cycloalkanones. A high degree of diastereoselectivity for the trans-fused product is observed in substrates having an ester group α to the cycloalkanone carbonyl. Bicyclic precursors lacking this ester group give mixtures of cis and trans products. Finally, contrary to previous reports, we have demonstrated that aniline can be substituted for nitrobenzene in these reactions.
- Bunce, Richard A.,Herron, Derrick M.,Lewis, Jason R.,Kotturi, Sharadsrikar V.
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p. 113 - 120
(2007/10/03)
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- The use of triphenylphosphine/diethyl azodicarboxylate (DEAD) for the cyclization of 1,4- and 1,5-amino alcohols
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Application of the Mitsunobu reagent to the cyclization of 1,4- and 1,5-amino alcohols provided an assortment of azacycles in good to excellent yield.
- Bernotas,Cube
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p. 161 - 164
(2007/10/02)
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- Novel Synthesis of the Pyrrolizidine Skeleton by Sulfenocycloamination. Total Synthesis of (+/-)-Retronecine and (+/-)-Turneforcidine
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The ω-unsaturated amines 1, 6, and 7 were converted into pyrrolidines 4 and 8 and piperidine 9, respectively, by treatment of their hydrochlorides with benzenesulfenyl chloride followed by base-induced ring closure.This novel sulfenocycloamination ring closure was applied to the synthesis of the pyrrolizidine ring (e.g., 20) and to the total synthesis of (+/-)-retronecine (32) and (+/-)-turneforcidine (34).
- Ohsawa, Tatsushi,Ihara, Masataka,Fukumoto, Keiichiro,Kametani, Tetsuji
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p. 3644 - 3648
(2007/10/02)
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