- Expanding Coefficient: A Parameter to Assess the Stability of Induced-Fit Complexes
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Here we propose a new parameter, the Expanding Coefficient (EC), that can be correlated with the thermodynamic stability of supramolecular complexes governed by weak secondary interactions and obeying the induced-fit model. The EC values show a good linear relationship with the log Kapp of the respective pseudorotaxane complexes investigated. According to Cram's Principle of Preorganization, the EC can be considered an approximate mechanical measure of the host's reorganization energy cost upon adopting the final bound geometry.
- Talotta, Carmen,Concilio, Gerardo,De Rosa, Margherita,Soriente, Annunziata,Gaeta, Carmine,Rescifina, Antonio,Ballester, Pablo,Neri, Placido
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supporting information
p. 1804 - 1808
(2021/03/08)
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- Transient imine as a directing group for the metal-free o-C-H borylation of benzaldehydes
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Organoboron reagents are important synthetic intermediates and have wide applications in synthetic organic chemistry. The selective borylation strategies that are currently in use largely rely on the use of transition-metal catalysts. Hence, identifying much milder conditions for transition-metal-free borylation would be highly desirable. We herein present a unified strategy for the selective C-H borylation of electron-deficient benzaldehyde derivatives using a simple metal-free approach, utilizing an imine transient directing group. The strategy covers a wide spectrum of reactions and (i) even highly sterically hindered C-H bonds can be borylated smoothly, (ii) despite the presence of other potential directing groups, the reaction selectively occurs at the o-C-H bond of the benzaldehyde moiety, and (iii) natural products appended to benzaldehyde derivatives can also give the appropriate borylated products. Moreover, the efficacy of the protocol was confirmed by the fact that the reaction proceeds even in the presence of a series of external impurities.
- Rej, Supriya,Chatani, Naoto
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supporting information
p. 2920 - 2929
(2021/03/01)
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- Trimethyl Borate-Catalyzed, Solvent-Free Reductive Amination
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Solvent-free reductive amination of aldehydes and ketones with aliphatic and aromatic amines in high-to-excellent yields has been achieved with sub-stoichiometric trimethyl borate as promoter and ammonia borane as reductant.
- Ramachandran, P. Veeraraghavan,Choudhary, Shivani,Singh, Aman
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p. 4274 - 4280
(2021/03/09)
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- Cobalt-Catalyzed Deoxygenative Hydroboration of Nitro Compounds and Applications to One-Pot Synthesis of Aldimines and Amides
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The commercially available and bench-stable Co(acac)2 ligated with bis[(2-diphenylphosphino)phenyl] ether (dpephos) was employed for selective room temperature hydroboration of nitro compounds with HBPin (TOF up to 4615 h?1), tolerating halide, hydroxy, amino, ether, ester, lactone, amide and heteroaromatic functionalities. These reactions offered a direct access to a variety of N-borylamines RN(H)BPin, which were in situ treated with aldehydes and carboxylic acids to produce a series of aldimines and secondary carboxamides without the need for dehydrating and/or coupling reagents. Combination of these transformations in a sequential one-pot manner allowed for direct and selective synthesis of aldimines and secondary carboxamides from readily available and inexpensive nitro compounds.
- Gudun, Kristina A.,Hayrapetyan, Davit,Khalimon, Andrey Y.,Segizbayev, Medet,Slamova, Ainur,Zakarina, Raikhan
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- 2D sp2 Carbon-Conjugated Porphyrin Covalent Organic Framework for Cooperative Photocatalysis with TEMPO
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2D covalent organic frameworks (COFs) are receiving ongoing attention in semiconductor photocatalysis. Herein, we present a photocatalytic selective chemical transformation by combining sp2 carbon-conjugated porphyrin-based covalent organic framework (Por-sp2c-COF) photocatalysis with TEMPO catalysis illuminated by 623 nm red light-emitting diodes (LEDs). Highly selective conversion of amines into imines was swiftly afforded in minutes. Specifically, the π-conjugation of porphyrin linker leads to extensive absorption of red light; the sp2 ?C=C? double bonds linkage ensures the stability of Por-sp2c-COF under high concentrations of amine. Most importantly, we found that crystalline framework of Por-sp2c-COF is pivotal for cooperative photocatalysis with (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO). This work foreshadows that the outstanding hallmarks of COFs, particularly crystallinity, could be exploited to address energy and environmental challenges by cooperative photocatalysis.
- Chen, Rufan,Hao, Huimin,Lang, Xianjun,Shi, Ji-Long,Wang, Cheng
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supporting information
p. 9088 - 9093
(2020/03/30)
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- A Carbazolyl Porphyrin-Based Conjugated Microporous Polymer for Metal-Free Photocatalytic Aerobic Oxidation Reactions
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Herein, a carbazolyl porphyrin-based π-conjugated microporous polymer was prepared via simple FeCl3-catalyzed oxidative polymerization. The resulting polymer (TCPP-CMP) exhibits high surface area, permanent pores, good stability, broad light absorption range and suitable redox potentials. As expected, TCPP-CMP is a highly effective metal-free and heterogeneous photocatalyst for a variety of aerobic oxidation reactions, including oxidative coupling of primary amines, oxidative dehydrogenation of secondary amines, and oxidation of sulfides into sulfoxides using molecular oxygen under visible light irradiation. Importantly, natural sunlight is able to promote the aerobic oxidation of benzylamine and thioanisole via TCPP-CMP photocatalyst with high conversion and selectivity, which are comparable with reactions conducted under artificial light. In addition, heterogeneous TCPP-CMP has good recyclability, which retained its activity even after four cycles. The current work lays the foundation for future applications of TCPP-CMP as metal-free heterogeneous photocatalyst for aerobic oxidation reactions.
- Jiang, Jun,Liang, Zhongxiu,Xiong, Xiaoyan,Zhou, Xiantai,Ji, Hongbing
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p. 3523 - 3529
(2020/05/25)
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- Cobalt-Catalyzed α-Arylation of Substituted α-Bromo α-Fluoro β-Lactams with Diaryl Zinc Reagents: Generalization to Functionalized Bromo Derivatives
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A cobalt-catalyzed cross-coupling of α-bromo α-fluoro β-lactams with diarylzinc or diallylzinc reagents is herein disclosed. The protocol proved to be general, chemoselective and operationally simple allowing the C4 functionalization of β-lactams. The substrate scope was expanded to α-bromo lactams and amides, α-bromo lactones and esters as well as N- and O-containing heterocycles.
- Br?se, Stefan,Chen, Hi-Yung,Cossy, Janine,Koch, Vanessa,Lei, Aiwen,Lorion, Mélanie M.,Nieger, Martin
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supporting information
p. 13163 - 13169
(2020/09/23)
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- Ni-Catalyzed asymmetric reduction of α-keto-β-lactams: via DKR enabled by proton shuttling
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Chiral α-hydroxy-β-lactams are key fragments of many bioactive compounds and antibiotics, and the development of efficient synthetic methods for these compounds is of great value. The highly enantioselective dynamic kinetic resolution (DKR) of α-keto-β-lactams was realized via a novel proton shuttling strategy. A wide range of α-keto-β-lactams were reduced efficiently and enantioselectively by Ni-catalyzed asymmetric hydrogenation, providing the corresponding α-hydroxy-β-lactam derivatives with high yields and enantioselectivities (up to 92% yield, up to 94% ee). Deuterium-labelling experiments indicate that phenylphosphinic acid plays a pivotal role in the DKR of α-keto-β-lactams by promoting the enolization process. The synthetic potential of this protocol was demonstrated by its application in the synthesis of a key intermediate of Taxol and (+)-epi-Cytoxazone. This journal is
- Wang, Fangyuan,Tan, Xuefeng,Wu, Ting,Zheng, Long-Sheng,Chen, Gen-Qiang,Zhang, Xumu
-
supporting information
p. 15557 - 15560
(2020/12/30)
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- Chemoselective photocatalytic oxidation of alcohols to aldehydes and ketones by nitromethane on titanium dioxide under violet 400 nm LED light irradiation
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In this study, for the first time, nitroalkanes, especially nitromethane, have been used as electron acceptors for the highly chemoselective oxidation of alcohols in the presence of a TiO2 photocatalyst under 400 nm LED irradiation. The reactions showed excellent selectivity for the production of aldehydes. Interestingly, aldehydes such as benzaldehyde and p-methoxybenzaldehyde are stable under the reaction conditions. In the case of the use of 2-nitropropane and 2-methyl-2-nitropropane, the product imine, which is the result of the reaction of the aldehyde with aliphatic amine, is also obtained.
- Kaboudin, Babak,Kazemi, Foad,Rahimi Niaraki, Azam,Saraee, Mohammad Reza
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p. 2326 - 2330
(2020/04/03)
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- Single Atomically Anchored Cobalt on Carbon Quantum Dots as Efficient Photocatalysts for Visible Light-Promoted Oxidation Reactions
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Generation of efficient light-induced charge separation inside the photocatalyst is an essential factor for a high catalytic efficiency. The usual immobilization of metal or metal oxide particles on semiconductor photocatalysts offers an uncontrolled assembly of active sites during the reaction. The introduction of single metal atoms on photocatalysts can lead to extremely high atomic utilization and precise active sites. However, this approach is limited because of the lack of suitable photosensitizers for single atom immobilization. Here, we have designed photocatalytic carbon quantum dots with anchoring sites for single cobalt atoms in a defined Co-N4 structure via facile pyrolysis of vitamin B12. Carbon dots functioned as both light-harvesting antenna and support for the cobalt atom with high atom loadings up to 3.27 wt %. This new photocatalytic material demonstrated enhanced visible light absorption, efficient charge separation, and reduced electrochemical impedance, while single Co atoms acted as the active site with strong oxidative ability. As a result, the photocatalysts showed excellent visible light-promoted photocatalytic efficiency with oxygen evolution rates up to 168 μmol h-1 g-1 via water oxidation, imine formation with high conversion (~90%) and selectivity (>99%), and complete photodegradation of organic dyes.
- Wang, Qin,Li, Jin,Tu, Xianjun,Liu, Hongbo,Shu, Miao,Si, Rui,Ferguson, Calum T. J.,Zhang, Kai. A. I.,Li, Run
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p. 734 - 743
(2020/02/04)
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- Visible-light harvesting pyrene-based MOFs as efficient ROS generators
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The utilization of reactive oxygen species (ROS) in organic transformations is of great interest due to their superior oxidative abilities under mild conditions. Recently, metal-organic frameworks (MOFs) have been developed as photosensitizers to transfer molecular oxygen to ROS for photochemical synthesis. However, visible-light responsive MOFs for oxygen activation remains scarce. Now we design and synthesize two porous MOFs, namely, PCN-822(M) (M = Zr, Hf), which are constructed by a 4,5,9,10-(K-region) substituted pyrene-based ligand, 4,4′,4′′,4′′′-((2,7-di-tert-butylpyrene-4,5,9,10-tetrayl)tetrakis(ethyne-2,1-diyl))-tetrabenzoate (BPETB4-). With the extended π-conjugated pyrene moieties isolated on the struts, the derived MOFs are highly responsive to visible light, possessing a broad-band adsorption from 225-650 nm. As a result, the MOFs can be applied as efficient ROS generators under visible-light irradiation, and the hafnium-based MOF, PCN-822(Hf), can promote the oxidation of amines to imines by activating molecular oxygen via synergistic photo-induced energy and charge transfer.
- Zhang, Yingmu,Pang, Jiandong,Li, Jialuo,Yang, Xinyu,Feng, Mingbao,Cai, Peiyu,Zhou, Hong-Cai
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p. 8455 - 8460
(2019/09/30)
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- A visible-light-responsive metal-organic framework for highly efficient and selective photocatalytic oxidation of amines and reduction of nitroaromatics
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Photocatalysis is a green synthetic method for organics transformation. We present here the synthesis of a novel visible-light-responsive metal-organic framework and its photocatalytic application. The prepared MOF is highly efficient for the self-coupling of primary amines and oxidative dehydrogenation of secondary amines to selectively produce imines assisted by the green and economic oxidant of molecular oxygen. Studies reveal that both energy transfer and electron transfer from the photoexcited MOF to molecular oxygen are important for amine oxidation, where the highly reactive species of superoxide radicals and singlet oxygen together account for the high catalytic performance. The photogenerated electrons of the MOF have also been utilized for the reduction of aromatic nitroarenes. Results show that they are highly selective for the reduction of nitroarenes to produce anilines in the presence of hydrazine hydrate. The work demonstrates the enormous potential of photoactive MOFs for converting organic substrates into valuable chemicals.
- Chen, Peiqi,Guo, Zhifen,Liu, Xin,Lv, Hui,Che, Yan,Bai, Rong,Chi, Yanhong,Xing, Hongzhu
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p. 27074 - 27080
(2019/12/11)
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- Activation of primary amines by copper(i)-based lewis acid promoters in the solventless synthesis of secondary propargylamines
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Primary amines are activated by copper(I)-based Lewis acid promoters in an A 3 -coupling one-pot solventless reaction with aldehydes and phenylacetylene for the synthesis of secondary propargylamines. The reaction is promoted by a CuSO 4 /NaI system, a practical precursor of the in situ generated effective CuI/I 2 system, that worked well, but only in a restricted number of examples. Substitution of I 2 with CeCl 3 ·7H 2 O in a one-pot two-step reaction provided good yields and a wider applicability, with the added value given by a safer procedure.
- Cimarelli, Cristina,Navazio, Federica,Rossi, Federico V.,Del Bello, Fabio,Marcantoni, Enrico
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p. 2387 - 2396
(2019/05/27)
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- Organocatalytic Mukaiyama Mannich Reactions of 2,5-Bis(trimethylsilyloxy)furan
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The organocatalytic synthesis of densely substituted mono- and bis-?-lactams involving the Mukaiyama Mannich addition of 2,5-bis(trimethylsilyloxy)furan to imines is described. Use of a ditoluenesulfonylimide catalyst produces ?-lactams from monoaddition, whereas a more acidic catalyst (triflic acid) produces fused bis-lactams from double addition. Optimized organocatalytic conditions allow for the selective synthesis of either desired core as well as the one-pot, multicomponent assembly of the trisubstituted monolactams from aldehydes, amines, and bis-trimethylsilyloxyfuran. An examination of chiral acids found these organocatalysts to be highly active and diastereoselective in the monoaddition reaction, albeit with no enantioselectivity.
- Laws, Stephen W.,Howard, Sara Y.,Mato, Raquel,Meng, Shuyu,Fettinger, James C.,Shaw, Jared T.
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supporting information
p. 5073 - 5077
(2019/07/03)
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- Cobalt-Catalyzed α-Arylation of Substituted α-Halogeno β-Lactams
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The treatment of 3-bromo β-lactams by an aryl Grignard, in the presence of CoCl2 (2 mol %) and TMEDA (2 mol %) in THF, produces 3-aryl β-lactams in good yields and excellent diastereoselectivity.
- Koch, Vanessa,Lorion, Mélanie M.,Barde, Etienne,Br?se, Stefan,Cossy, Janine
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supporting information
p. 6241 - 6244
(2019/08/26)
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- N–Alkylation of Amines Catalyzed by a Ruthenium–Pincer Complex in the Presence of in situ Generated Sodium Alkoxide
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We report the use of ruthenium–NNN-pincer complexes of the type (R2NNN)RuCl2(PPh3) (R = tBu, iPr, Cy and Ph) for the catalytic N-alkylation of primary amines under solvent-free conditions. For the first time, the base that is required to promote these reactions is generated in situ from the alcohol by the use of sodium. The resulting sodium alkoxide regenerates the alcohol substrate while acting as the water scavenger thus mitigating the need of an additional base. Among the catalysts screened, (tBu2NNN)RuCl2(PPh3) (0.02 mol-%) gives very high turnovers and good yields at 140 °C. The (tBu2NNN)RuCl2(PPh3) catalyzed N-alkylation tolerates a variety of amine and alcohol substrates. While excellent turnover (29000) was obtained for the (tBu2NNN)RuCl2(PPh3) (0.002 mol-%) catalyzed alkylation of aniline with cyclohexyl methanol, the turnovers obtained in the corresponding catalytic methylation of p-anisidine was also very high (12000). The (tBu2NNN)RuCl2(PPh3) catalyzed reactions have also been accomplished under open-vessel conditions resulting in a net dehydrogenative coupling reaction. This protocol has been used to transform benzene-1,2-diamines to benzimidazoles with high productivity (12000 turnovers). DFT studies indicate that while β-hydride elimination is rate-determining (RDTS: 24.31 kcal/mol) for the alcohol dehydrogenation segment which is endothermic, insertion of the imine is rate-determining (RDTS: 11.26 kcal/mol) for its hydrogenation that is exothermic.
- Das, Kanu,Nandi, Pran Gobinda,Islam, Khadimul,Srivastava, Hemant Kumar,Kumar, Akshai
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p. 6855 - 6866
(2019/11/03)
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- Metal–Organic Frameworks with Organogold(III) Complexes for Photocatalytic Amine Oxidation with Enhanced Efficiency and Selectivity
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Luminescent organogold(III) complex AuIII with highly emissive triplet excited state was encapsulated in two metal–organic frameworks (MOFs) with different pore sizes and structures (MOF1 and ZJU-28). Compared with the AuIII complex in solution, the resultant composites AuIII@MOF1 and AuIII@ZJU-28 exhibit enhanced emission intensity, lifetime, and quantum yield. Under irradiation, AuIII@MOFs are efficient, selective, and recyclable catalysts for light-induced aerobic C?N bond formation. When used as a heterogeneous catalyst for oxidizing secondary amines to the corresponding imines, AuIII@ZJU-28 achieved high TONs of 876–1548, which are about 2.8–3.5 times higher than that of the homogenous AuIII complex. In addition, different selectivities in oxidizing mixed substrates is realized by means of different host MOFs, and thus encapsulating the AuIII complex in an appropriate MOF allowed the desired product to be obtained. Inherent shortcomings of homogeneous catalysts in cyclic use are also overcome by using composite catalysts, and high conversion of the AuIII@ZJU-28 catalyst was still observed after ten cycles.
- Han, Qing,Wang, Yue-Lin,Sun, Min,Sun, Chun-Yi,Zhu, Shan-Shan,Wang, Xin-Long,Su, Zhong-Min
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p. 15089 - 15095
(2018/09/14)
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- Method for synthesizing imine by catalytic oxidation of asymmetric secondary amine in presence of visible light
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The invention belongs to the technical field of chemical engineering and pharmaceutical industry, and particularly relates to a method for synthesizing imine by catalytic oxidation of asymmetric secondary amine in the presence of visible light. With aza-metalloporphyrin containing sulfur as a visible light catalyst, 1,8-diazabicycloundecene-7-alkene as an auxiliary agent, and oxygen as an oxidant,asymmetric secondary amine is subjected to catalytic oxidation under irradiation of visible light of lambda being larger than or equal to 420nm, so as to obtain the oxidation product imine. A new andefficient imine production way is provided.
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Paragraph 0025-0026; 0060-0064
(2018/11/22)
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- Carbonylation Access to Phthalimides Using Self-Sufficient Directing Group and Nucleophile
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Herein we report a novel palladium-catalyzed oxidative carbonylation reaction for the synthesis of phthalimides with high atom- and step-economy. In our strategy, the imine and H2O, which are generated in situ from the condensation of aldehyde and amine, serve as self-sufficient directing group and nucleophile, respectively. This method provides rapid access to phthalimides starting from readily available materials in a one-pot manner. Various phthalimide derivatives are constructed efficiently, including medicinally and biologically active phthalimide-containing compounds.
- Ji, Fanghua,Li, Jianxiao,Li, Xianwei,Guo, Wei,Wu, Wanqing,Jiang, Huanfeng
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p. 104 - 112
(2018/02/19)
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- Ligand-Controlled Inversion of Diastereo- and Enantioselectivity in Silver-Catalyzed Azomethine Ylide-Imine Cycloaddition of Glycine Aldimino Esters with Imines
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A highly diastereo- and enantioselective silver-catalyzed azomethine ylide-imine (AYI) cycloaddition reaction of glycine aldimino esters with imines was developed in which the Xing-Phos-controlled syn-selective or DTBM-Segphos-induced anti-selective AYI cycloaddition reaction could be applied to the synthesis of a variety of stereodivergent 1-alkyl-2,5-substituted imidazolidines with high yields and excellent enantioselectivities (up to 99% ee) as well as good diastereoselectivities (up to 99:1 dr) under mild reaction conditions.
- Yu, Bo,Yang, Ke-Fang,Bai, Xing-Feng,Cao, Jian,Zheng, Zhan-Jiang,Cui, Yu-Ming,Xu, Zheng,Li, Li,Xu, Li-Wen
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supporting information
p. 2551 - 2554
(2018/05/17)
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- Development of a metal-free amine oxidation method utilizing DEAD chemistry
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Herein, we examine the oxidative abilities of azodicarboxylates for the conversion of amines to imines. This method provides access to synthetically useful imine intermediates including β-carbolines, quinazolines and N-heterocyclic carbene precursors. The ability to recover spent azodicarboxylate for regeneration and further use underscores the applicability and appeal of this protocol.
- Wang,Piva De Silva,Wiebe,Fehr,Davis
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p. 48848 - 48852
(2017/11/06)
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- Tf2O-TMDS combination for the direct reductive transformation of secondary amides to aldimines, aldehydes, and/or amines
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The direct partial reduction of highly stable secondary amides to more reactive aldimines and aldehydes is a challenging yet highly demanding transformation. In this context, only three methods have been reported. We report herein an improved version of the Charette’s method. Our protocol consists of activation of secondary amides with triflic anhydride/2-fluoropyridine, and partial reduction of the resulting intermediates with 1,1,3,3-tetramethyldisiloxane (TMDS), which delivered aldimines or aldehydes upon acidic hydrolysis. Aromatic amides were reduced to the corresponding aldimines in 85%–100% NMR yields, and yields (NMR) from aliphatic amides were 72%–86%. Acidic hydrolysis of the aldimine intermediates afforded, in one-pot, the corresponding aldehydes in 80%–96% yields. A simple protocol was established to isolate labile aldimines in pure form in 92%–96% yields. The improved method gave generally higher yields as compared to the known ones, and features the use of cheaper and more atom-economical TMDS as a chemoselective reducing agent. In addition, a convenient extraction protocol has been established to allow the isolation of amines, which constitutes a mild method for the N-deacylation of amides, another highly desirable transformation. The extended method retains the advantages of the original method of Charette in terms of mild conditions, good functional group tolerance, and excellent chemoselectivity.
- Lang, Qi-Wei,Hu, Xiu-Ning,Huang, Pei-Qiang
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p. 1638 - 1644
(2016/12/07)
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- A telescopic one-pot synthesis of β-lactam rings using amines as a convenient source of imines
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A facile synthetic approach to substituted β-lactams was designed, using secondary benzylic amines and acid chlorides as starting materials. The reactions proceeded smoothly and all the products were obtained in good yields.
- Rajam?ki, Suvi H. M.,De Luca, Lidia,Capitta, Francesca,Porcheddu, Andrea
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p. 38553 - 38557
(2016/06/01)
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- Formal Ir-Catalyzed Ligand-Enabled Ortho and Meta Borylation of Aromatic Aldehydes via in Situ-Generated Imines
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The ligand-enabled development of ortho and meta C-H borylation of aromatic aldehydes is reported. It was envisaged that while ortho borylation could be achieved using tert-butylamine as the traceless protecting/directing group, meta borylation proceeds via an electrostatic interaction and a secondary interaction between the ligand of the catalyst and the substrate. These ligand-substrate electrostatic interactions and secondary B-N interactions provide an unprecedented controlling factor for meta-selective C-H activation/borylation.
- Bisht, Ranjana,Chattopadhyay, Buddhadeb
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supporting information
p. 84 - 87
(2016/01/25)
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- Diastereoselective Synthesis of and Mechanistic Understanding for the Formation of 2-Piperidinones from Imines and Cyano-Substituted Anhydrides
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2-Piperidinones are synthesized in a single step from imines and 2-cyano glutaric anhydrides. The reaction provides the products in good diastereoselectivity and generates a quaternary stereogenic center. Substitutions on the anhydride skeleton are well tolerated to provide 2-piperidinones with three stereogenic centers from a single transformation. The pertinent transition structures have also been computed using quantum mechanics and reveal the key interactions controlling the stereochemical outcome of the reaction.
- Di Maso, Michael J.,Snyder, Kevin M.,De Souza Fernandes, Fábio,Pattawong, Ommidala,Tan, Darlene Q.,Fettinger, James C.,Cheong, Paul Ha-Yeon,Shaw, Jared T.
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supporting information
p. 4794 - 4801
(2016/04/05)
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- Long-chain NHC-stabilized RuNPs as versatile catalysts for one-pot oxidation/hydrogenation reactions
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The synthesis and catalytic activity of long-chain NHC-stabilized RuNPs are presented. Full characterization of these novel nanostructures including surface state studies show that the ligand influences the number and the location of Ru active sites which impacts the NP catalytic activity, especially in hydrogenation reactions. The high stability and versatility of these nanosystems make them successful catalysts for both oxidation and hydrogenation reactions that can even be performed successively in a one pot-fashion.
- Martínez-Prieto,Ferry,Rakers,Richter,Lecante,Philippot,Chaudret,Glorius
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p. 4768 - 4771
(2016/04/09)
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- Hydrogen peroxide/dimethyl carbonate: A green system for epoxidation of: N -alkylimines and N -sulfonylimines. One-pot synthesis of N -alkyloxaziridines from N -alkylamines and (hetero)aromatic aldehydes
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A green method for epoxidation of imines using an environmentally benign oxidant system, H2O2/dimethyl carbonate, was developed. N-Alkyloxaziridines were prepared in high yields from N-alkylamines and (hetero)aromatic aldehydes in one-pot fashion, whereas N-sulfonyloxaziridines have been prepared by using the same oxidant system and 5 mol% of Zn(OAc)2·2H2O as catalyst.
- Kra?em, Jamil,Ghedira, Donia,Ollevier, Thierry
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supporting information
p. 4859 - 4864
(2016/10/12)
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- IMPROVED PRODUCTION METHOD FOR OXYDATION PRODUCT BY OPTICAL OXYGEN OXIDATION
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PROBLEM TO BE SOLVED: To provide an improved optical oxygen oxidation method for an organic compound in which reaction can be progressed by high speed and efficiency, and also, the use of a photosensitizer can be reduced or made needless. SOLUTION: Provided is an improved production method in the production of a product by the optical oxygen oxidation of a raw material organic compound, characterized in that a solution containing the raw material organic compound placed under light irradiation is injected with an oxygen-containing gas in the form of nanobubbles, and the state where the nanobubbles of the oxygen-containing gas are dispersed into the solution is retained, thus the optical oxygen oxidation reaction of the raw material organic compound is progressed to obtain the product. COPYRIGHT: (C)2015,JPOandINPIT
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Paragraph 0056-0060
(2017/01/02)
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- Highly efficient aerobic oxidation of various amines using Pd3Pb intermetallic compounds as catalysts
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Intermetallic Pd3Pb supported on Al2O3 can act as a highly efficient heterogeneous catalyst for the oxidation of various amines including primary, secondary, aromatic, aliphatic, and cyclic amines. The Royal Society of Chemistry 2014.
- Furukawa, Shinya,Suga, Akifusa,Komatsu, Takayuki
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p. 3277 - 3280
(2014/03/21)
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- Luminescent monocyclometalated cationic gold(iii) complexes: Synthesis, photophysical characterization and catalytic investigations
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Stable, luminescent, and cationic monocyclometalated gold(iii) monoaryl complexes of the type [(ppy)Au(FMes)(L)]+[OTf]- [L = 4-phenylpyridine (3), quinoline (4), 4-fluoroaniline (5), P(OMe)3 (6), PPh3 (7)], bearing different ancillary ligands, synthesized starting from the precursor complex [(ppy)Au(FMes)(OH2)] +[OTf]- (2) are reported. The preliminary assignment of the structure of the complexes by various nuclear magnetic resonance spectroscopy techniques and elemental analysis has been further corroborated by single-crystal X-ray diffraction studies. The complexes exhibit room temperature phosphorescence in solution, in neat solids and in doped PMMA films. Detailed photophysical investigations of the complexes in solution, in neat solids and in PMMA films revealed the successful tuning of the emission quantum yield ( p) based on the electronic properties of the ancillary ligands. The catalytic photo-oxidation of benzylic amines to their corresponding imines using molecular oxygen as the oxidant was successfully achieved in the presence of the luminescent Au(iii) complexes. It is also established that the photocatalytic performance was strongly governed by the electronic properties of the ancillary ligands on the photosensitizer as well as by the steric bulk of the substrates. This journal is the Partner Organisations 2014.
- Zehnder, Thomas N.,Blacque, Olivier,Venkatesan, Koushik
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p. 11959 - 11972
(2014/08/05)
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- Diastereoselective synthesis of γ- And δ-lactams from imines and sulfone-substituted anhydrides
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Sulfone-substituted γ- and δ-lactams have been prepared in a single step with high diastereoselectivity. Sulfonylglutaric anhydrides produce intermediates that readily decarboxylate to provide δ-lactams with high diastereoselectivity. Substituents at the 3- or 4-position of the glutaric anhydride induce high levels of stereocontrol. Sulfonylsuccinic anhydrides produce intermediate carboxylic acids that can be trapped as methyl esters or allowed to decarboxylate under mild conditions. This method has been applied to a short synthesis of the pyrrolizidine alkaloid (±)-isoretronecanol.
- Sorto, Nohemy A.,Di Maso, Michael J.,Munoz, Manuel A.,Dougherty, Ryan J.,Fettinger, James C.,Shaw, Jared T.
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p. 2601 - 2610
(2014/04/17)
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- Synthesis of new biologically active isothiazolo[4,5-b]carbazole-type tetracyclic derivatives via an indole-2,3-quinodimethane approach
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A number of isothiazolo[4,5-b]carbazole derivatives were prepared via a Diels-Alder approach involving thermally induced indole-2,3-quinodimethane intermediates. Preliminary biological tests revealed a GSK-3β kinase inhibitor (29) and some free NH group containing compounds (17d, 19c, 29) displayed selective human carbonic anhydrase I inhibitory activities.
- Miambo, Raimundo F.,Laronze-Cochard, Marie,Lawson, Ata-Martin,Guillot, Régis,Baldeyrou, Brigitte,Lansiaux, Amélie,Supuran, Claudiu T.,Sapi, Janos
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p. 8286 - 8302
(2015/03/05)
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- Aerobic oxidative N-dealkylation of secondary amines in aqueous solution catalyzed by rhodium porphyrins
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N-dealkylation demonstrates an important biochemical oxidation reaction by cytochrome P450 and other monooxygenases. In this article, catalytic oxidative N-dealkylation of secondary amines was achieved using rhodium(III) tetra (p-sulfonato-phenyl) porphyrin ((TSPP)RhIII) in aqueous solution with oxygen as the sole oxidant. Addition of benzaldehyde to trap primary amine product inhibited catalyst deactivation and dramatically increased reaction turnover numbers (TONs). Substrate scope examination suggested the reaction was performed with a preference for bulkier secondary amines. Kinetic study exhibited first-order kinetics with regard of (TSPP)RhIII catalyst. Results from the Hammett study gave a σ value of -1.38, suggesting formation of an iminium ion intermediate in the rate determining step.
- Yun, Lin,Zhen, Ling,Wang, Zikuan,Fu, Xuefeng
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p. 937 - 943
(2015/05/27)
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- Aerobic oxidative N-dealkylation of secondary amines in aqueous solution catalyzed by rhodium porphyrins
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N-dealkylation demonstrates an important biochemical oxidation reaction by cytochrome P450 and other monooxygenases. In this article, catalytic oxidative N-dealkylation of secondary amines was achieved using rhodium(III) tetra (p-sulfonato-phenyl) porphyrin ((TSPP)RhIII) in aqueous solution with oxygen as the sole oxidant. Addition of benzaldehyde to trap primary amine product inhibited catalyst deactivation and dramatically increased reaction turnover numbers (TONs). Substrate scope examination suggested the reaction was performed with a preference for bulkier secondary amines. Kinetic study exhibited first-order kinetics with regard of (TSPP)RhIII catalyst. Results from the Hammett study gave a ρ value of -1.38, suggesting formation of an iminium ion intermediate in the rate determining step.
- Yun, Lin,Zhen, Ling,Wang, Zikuan,Fu, Xuefeng
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p. 937 - 943
(2015/06/16)
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- A robust palladium(II)-Porphyrin complex as catalyst for visible light induced oxidative C-H functionalization
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A series of palladium(II)-porphyrin complexes that display dual emissions with lifetimes up to 437μs have been synthesized. Among the four complexes, PdF20TPP is an efficient and robust catalyst for photoinduced oxidative C-H functionalization by using oxygen as terminal oxidant. α-Functionalized tertiary amines were obtained in good to excellent yields by light irradiation (λ>400nm) of a mixture of PdF20TPP, tertiary amine, and nucleophile (cyanide, nitromethane, dimethyl malonate, diethyl phosphite, and acetone) under aerobic conditions. Four examples of intramolecular cyclized amine compounds could be similarly prepared. Comparison of the UV-visible absorption spectra before and after the photochemical reaction revealed that PdF20TPP was highly robust (>95 % recovery). The practical application of PdF20TPP has been revealed by the photochemical reactions performed by using a low catalyst loading (0.01mol %) and on a 10mmol scale. The PdF20TPP catalyst could sensitize photoinduced oxidation of sulfides to sulfoxides in excellent yields. Mechanistic studies revealed that the photocatalysis proceeded by singlet-oxygen oxidation. Long-lived excited states! A series of palladium(II)-porphyrin complexes have been synthesized and found to display long-lived excited states with lifetimes up to 437μs (see scheme). Among these complexes, PdF 20TPP is an efficient and robust catalyst for a broad array of photoinduced oxidative C-H functionalization reactions. PtF20TPP= platinum(II) meso-tetrakis(2,3,4,5,6-pentafluorophenyl)porphyrin.
- To, Wai-Pong,Liu, Yungen,Lau, Tai-Chu,Che, Chi-Ming
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supporting information
p. 5654 - 5664
(2013/06/04)
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- Bodipy derivatives as organic triplet photosensitizers for aerobic photoorganocatalytic oxidative coupling of amines and photooxidation of dihydroxylnaphthalenes
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We used iodo-Bodipy derivatives that show strong absorption of visible light and long-lived triplet excited states as organic catalysts for photoredox catalytic organic reactions. Conventionally most of the photocatalysts are based on the off-the-shelf compounds, usually showing weak absorption in the visible region and short triplet excited state lifetimes. Herein, the organic catalysts are used for two photocatalyzed reactions mediated by singlet oxygen ( 1O2), that is, the aerobic oxidative coupling of amines and the photooxidation of dihydroxylnaphthalenes, which is coupled to the subsequent addition of amines to the naphthoquinones, via C-H functionalization of 1,4-naphthoquinone, to produce N-aryl-2-amino-1,4-naphthoquinones (one-pot reaction), which are anticancer and antibiotic reagents. The photoreactions were substantially accelerated with these new iodo-Bodipy organic photocatalysts compared to that catalyzed with the conventional Ru(II)/Ir(III) complexes, which show weak absorption in the visible region and short-lived triplet excited states. Our results will inspire the design and application of new organic triplet photosensitizers that show strong absorption of visible light and long-lived triplet excited state and the application of these catalysts in photoredox catalytic organic reactions.
- Huang, Ling,Zhao, Jianzhang,Guo, Song,Zhang, Caishun,Ma, Jie
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supporting information
p. 5627 - 5637
(2013/07/25)
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- Dearomative radical spirocyclization from N-ce: Raghubenzyltrichloroacetamides revisited using a copper(I)-mediated atom transfer reaction leading to 2-azaspiro[4.5]decanes
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An atom transfer radical dearomatizing spirocyclization from N-benzyltrichloroacetamides using CuCl regioselectively leads to 2-azaspiro[4.5]decadienes, in which the labile allylic chlorine atom is easily replaced by a hydroxyl group in aqueous medium or by quenching with methanol or allylamine. After oxidation of the target compound, the N-tert-butyl group can be removed from the resulting spirocyclohexanedienone.
- Diaba, Fa?za,Montiel, Juan A.,Martínez-Laporta, Agustín,Bonjoch, Josep
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supporting information
p. 2619 - 2622
(2013/06/05)
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- Luminescent organogold(III) complexes with long-lived triplet excited states for light-induced oxidative C-H bond functionalization and hydrogen production
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All that glitters is gold: Highly phosphorescent gold(III) complexes (see picture) with extended π-conjugated cyclometalating ligands exhibit rich photophysical and photochemical properties. They act as efficient photocatalysts/photosensitizers for oxidative functionalizations of secondary and tertiary benzylic amines and homogeneous hydrogen production from a water/acetonitrile mixture. Copyright
- To, Wai-Pong,Tong, Glenna So-Ming,Lu, Wei,Ma, Chensheng,Liu, Jia,Chow, Andy Lok-Fung,Che, Chi-Ming
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supporting information; experimental part
p. 2654 - 2657
(2012/04/17)
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- Synthesis of a γ-lactam library via formal cycloaddition of imines and substituted succinic anhydrides
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Formal cycloaddition reactions between imines and cyclic anhydrides serve as starting point for the synthesis of diverse libraries of small molecules. The synthesis of succinic anhydrides substituted with electron-withdrawing groups is facilitated by new mild conditions for alkylation of aryl-substituted acetyl esters with ethyl bromoacetate. These anhydrides are then used in formal cycloaddition reactions with imines to produce γ-lactams. 2-Fluoro-5-nitrophenylsuccinic anhydride reacts efficiently with imines to provide lactams that are further diversified by conversion of the nitro group to either an aniline and an azide for subsequent reactions with acylating agents and alkynes, respectively. The synthesis of cyanosuccinic anhydride is reported for the first time, and the use of this compound in reactions with imines and subsequent functionalization of the resultant lactams is demonstrated.
- Tan, Darlene Q.,Atherton, Amy L.,Smith, Austin J.,Soldi, Cristian,Hurley, Katherine A.,Fettinger, James C.,Shaw, Jared T.
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body text
p. 218 - 223
(2012/05/07)
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- Design, synthesis, and antiviral evaluation of purine-β-lactam and purine-aminopropanol hybrids
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Purine-β-lactam chimera were prepared as a novel class of hybrid systems through N-alkylation of 6-benzylamino- or 6-benzyloxypurine with (ω-haloalkyl)-β-lactams, followed by reductive ring opening of the β-lactam ring by LiEt3BH to provide an entry into the class of purine-aminopropanol hybrids. Both new types of hybrid systems were assessed for their antiviral activity and cytotoxicity, resulting in the identification of eight purine-β-lactam hybrids and two purine-aminopropanol hybrids as promising lead structures.
- D'Hooghe, Matthias,Mollet, Karen,De Vreese, Rob,Jonckers, Tim H. M.,Dams, Géry,De Kimpe, Norbert
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scheme or table
p. 5637 - 5641
(2012/08/29)
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- Visible-light-induced selective photocatalytic aerobic oxidation of amines into imines on TiO2
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Imines are important intermediates for the synthesis of fine chemicals, pharmaceuticals, and agricultural chemicals. Selective oxidation of amines into their corresponding imines with dioxygen is one of the most-fundamental chemical transformations. Herein, we report the oxidation of a series of benzylic amines into their corresponding imines with atmospheric dioxygen as the oxidant on a surface of anatase TiO2 under visible-light irradiation (λ>420 nm). The visible-light response of this system was caused by the formation of a surface complex through the adsorption of a benzylic amine onto the surface of TiO2. From the analysis of products of specially designed benzylic amines, we demonstrated that a highly selective oxygenation reaction proceeds via an oxygen-transfer mechanism to afford the corresponding carbonyl compound, whose further condensation with an amine would generate the final imine product. We found that when primary benzylic amines (13 examples), were chosen as the substrates, moderate to excellent selectivities for the imine products were achieved (ca. 38-94%) in moderate to excellent conversion rates (ca. 44-95%). When secondary benzylic amines (15 examples) were chosen as the substrates, both the corresponding imines and aldehydes were detected as the main products with moderate to high conversion rates (ca. 18-100%) and lower selectivities for the imine products (ca. 14-69%). When tribenzylamine was chosen as the substrate, imine (27%), dibenzylamine (24%), and benzaldehyde products (39%) were obtained in a conversion of 50%. This report can be viewed as a prototypical system for the activation of C-H bonds adjacent to heteroatoms such as N, O, and S atoms, and oxofuctionalization with air or dioxygen as the terminal oxidant under visible-light irradiation using TiO2 as the photocatalyst. Go green! Visible-light irradiation of a surface complex of benzylic amines adsorbed onto a TiO2 surface induces charge-transfer; an oxygen-transfer mechanism affords the corresponding carbonyl compounds and condensation with an amine generates the imine product. Copyright
- Lang, Xianjun,Ma, Wanhong,Zhao, Yubao,Chen, Chuncheng,Ji, Hongwei,Zhao, Jincai
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experimental part
p. 2624 - 2631
(2012/03/27)
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- Aerobic oxidative coupling of amines by carbon nitride photocatalysis with visible light
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Coupling on sunshine: A simple and efficient synthesis of benzoxazoles, benzimidazoles, and benzothiazoles is realized through a one-pot preparation driven by a photocatalytic cascade reaction. Carbon nitride and visible light are employed to achieve this metal-free aerobic oxidation of amines to imines (see scheme; mpg-C3N4=mesoporous graphite carbon nitride). Copyright
- Su, Fangzheng,Mathew, Smitha C.,Moehlmann, Lennart,Antonietti, Markus,Wang, Xinchen,Blechert, Siegfried
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supporting information; experimental part
p. 657 - 660
(2011/03/19)
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- Application of sequential Cu(I)/Pd(0)-catalysis to solution-phase parallel synthesis of combinatorial libraries of dihydroindeno[1,2-c]isoquinolines
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Parallel solution-phase synthesis of combinatorial libraries of dihydroindenoisoquinolines employing a sequential Cu(I)/Pd(0)-catalyzed multicomponent coupling and annulation protocol was realized. The scope and limitations of the protocol with respect to the substitution pattern in the aryl ring of the indene core, as well as the N-substituent have been defined, revealing that the methodology is compatible with a wide-range of aliphatic linear, branched, and ester functionalized N-substituents. Unexpectedly, the formation of regioisomers featuring a 1,2,3-contiguous substitution pattern in the aromatic ring of the indene core was observed. Three distinct combinatorial libraries with a total of 111 of members were synthesized, and 80 highly substituted dihydroindenoisoquinolines structurally related to known medicinal agents including some consisting of mixtures of two regioisomers were made available for biological activity testing.
- Kumar, Sarvesh,Painter, Thomas O.,Pal, Benoy K.,Neuenswander, Benjamin,Malinakova, Helena C.
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body text
p. 466 - 477
(2011/11/06)
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- Stereoselective synthesis of trans- and cis-2-aryl-3-(hydroxymethyl) aziridines through transformation of 4-aryl-3-chloro-β-lactams and study of their ring opening
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trans- and cis-1-Alkyl-4-aryl-3-chloroazetidin-2-ones, prepared through cyclocondensation of chloroketene and the appropriate imines in a diastereoselective way, were transformed into the corresponding non-activated trans- and cis-2-aryl-3-(hydroxymethyl)aziridines via reductive ring contraction using LiAlH4 in Et2O. Furthermore, trans-2-aryl-3- (hydroxymethyl)aziridines were transformed into 2-amino-3-arylpropan-1-ols and anti-2-amino-3-aryl-3-methoxypropan-1-ols by means of an unprecedented ring opening by LiAlH4 and by MeOH, respectively. cis-2-Aryl-3- (hydroxymethyl)aziridines were shown to be highly reluctant to undergo ring opening by LiAlH4 and MeOH under similar reaction conditions.
- D'Hooghe, Matthias,Mollet, Karen,Dekeukeleire, Stijn,De Kimpe, Norbert
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body text
p. 607 - 615
(2010/04/30)
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- Synthesis of densely substituted trans-configured 4-acylated piperidine-2,4-diones as 3:1 Adducts of imines and ketenes
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An operationally simple method is described to form densely substituted diastereomerically pure trans-configured and potentially biologically interesting 5,6-dihydropyridone derivatives as 3:1 adducts of ketenes formed in situ from acyl bromides and aromatic imines.
- Cabrera, Jose,Hellmuth, Tina,Peters, Rene
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experimental part
p. 4326 - 4329
(2010/09/03)
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- Cationic iridium complex is a new and efficient Lewis acid catalyst for aldol and Mannich reactions
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A cationic iridium complex [Ir(cod)2]SbF6 was found to be a new and efficient Lewis acid catalyst for Mukaiyama aldol and Mannich reactions. Aldehydes react smoothly with silyl enol ethers to give β-siloxy ketones in the presence of 0.5 mol % of [Ir(cod)2]SbF6. The reaction of N-alkyl arylaldimines with ketene silyl acetals in the presence of 5 mol % [Ir(cod)2]SbF6/P(OPh)3 gave β-amino esters. After Mannich reaction was complete, stirring of the reaction mixture for 24 h led to cyclization to give β-lactam. The reaction of N-aryl benzaldimine with silyl enol ether derived from acetophenone gave a tetrahydroquinoline derivative as a single diastereomer.
- Onodera, Gen,Toeda, Takayuki,Toda, Nou-No,Shibagishi, Daigo,Takeuchi, Ryo
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experimental part
p. 9021 - 9031
(2011/01/04)
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- Synthesis of dihydrobenzisoxazoles by the [3 + 2] cycloaddition of arynes and oxaziridines
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Dihydrobenzisoxazoles are readily prepared in good yields by the [3 + 2] cycloaddition of oxaziridines and arynes. The reaction involves an unusual cleavage of the C-O bond of the oxaziridine and tolerates a variety of substituents on the oxaziridine and the o-(trimethylsilyl)aryl triflate to form aryl-, heteroaryl-, alkyl-, and naphthyl-substituted dihydrobenzisoxazoles. The resulting halogen-substituted dihydrobenzisoxazoles are readily elaborated to more complex products using palladium-catalyzed crossing-coupling processes.
- Kivrak, Arif,Larock, Richard C.
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supporting information; experimental part
p. 7381 - 7387
(2011/02/22)
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- Highly efficient oxidation of amines to imines by singlet oxygen and its application in ugi-type reactions
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A variety of secondary benzylic amines were oxidized to imines in 90% to >99% yields by singlet oxygen generated from oxygen and a porphyrin photosensitizer. On the basis of these reactions, a protocol was developed for oxidative Ugi-type reactions with singlet oxygen as the oxidant. This protocol has been used to synthesize C1- and N-functionalized benzylic amines in up to 96% yields.
- Jiang, Gaoxl,Chen, Jian,Huang, Jie-Sheng,Che, Chi-Ming
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supporting information; experimental part
p. 4568 - 4571
(2009/12/07)
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- Synthesis of novel 2-alkoxy-3-amino-3-arylpropan-1-ols and 5-alkoxy-4-aryl-1,3-oxazinanes with antimalarial activity
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A variety of novel syn-2-alkoxy-3-amino-3-arylpropan-1-ols was prepared through LiAlH4-promoted reductive ring-opening of cis-3-alkoxy-4-aryl-β-lactams in Et2O. The latter γ-aminoalcohols were easily converted into cis-5-alkoxy-4-aryl-1,3- oxazinanes using formaldehyde in THF. Both series of compounds were evaluated against a chloroquine sensitive strain of Plasmodium falciparum (D10), revealing micromolar potency for almost all representatives. Eleven compounds exhibited antimalarial activity with IC50 values of ≤30 μM, and the majority of these compounds did not show cytotoxicity at the concentrations tested.
- D'hooghe, Matthias,Dekeukeleire, Stijn,Mollet, Karen,Lategan, Carmen,Smith, Peter J.,Chibale, Kelly,De Kimpe, Norbert
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body text
p. 4058 - 4062
(2009/12/28)
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- Facile and efficient method for preparation of Schiff bases catalyzed by P2O5/SiO2 under free Solvent conditions
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A simple and convenient method for the preparation of Schiff bases is developed. In this method, the Schiff base compounds were prepared from the reaction of carbonyl compounds with primary amines. In this reaction, P 2O5/SiO2 have catalyzed the Schiff base formation in dry media under solvent-free conditions. Advantages of this method are use of an inexpensive and efficient catalyst, high yields of products, short reaction times, and simplicity of the reaction and workup.
- Naeimi, Hossein,Sharghi, Hashem,Salimi, Fariba,Rabiei, Khadijeh
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