- Supramolecular Engineering of Discrete Pt(II)?Pt(II) Interactions for Visible-Light Photocatalysis
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Visible-light photosensitizers have emerged as a sustainable and environmentally friendly medium for organic transformation. Herein, we have developed a supramolecular strategy for manipulating visible-light photosensitization and photocatalytic efficienc
- Li, Zijian,Han, Yifei,Gao, Zongchun,Wang, Feng
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- Chromium-Catalyzed Reductive Cleavage of Unactivated Aromatic and Benzylic C-O Bonds
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Reductive cleavage of aromatic and benzylic C-O bonds by chromium catalysis is reported. This deoxygenative reaction was promoted by low-cost CrCl 2precatalyst combined with poly(methyl hydrogen siloxane) as the mild reducing agent, providing a strategy in forming reduced motifs by cleavage of unactivated C-O bonds. A range of functional groups such as bromide, chloride, fluoride, hydroxyl, amino, and alkoxycarbonyl can be retained in the reduction.
- Yuan, Shuqing,Ling, Liang,Tang, Jinghua,Luo, Meiming,Zeng, Xiaoming
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p. 3343 - 3350
(2021/07/02)
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- Metal- and oxidant-free electrochemically promoted oxidative coupling of amines
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The selective oxidation of amines into imines is a priority research topic in organic synthesis and has attracted much attention over the past few decades. However, the oxidation of amines generally suffers from the drawback of transition-metal, even noble-metal catalysts. Thus, the strategy of metal- and oxidant-free selective synthesis of imines is highly desirable yet largely unmet. This paper unravels a metal-free and external oxidant-free electrochemical strategy for the oxidative coupling methodology of amines. This general transformation is compatible with various functional amines and led to functionalized imines in moderate to satisfactory yields.
- Chen, Hengyu,Hu, Xiude,Huang, Xianqiang,Li, Jiashuai,Li, Zhen,Liu, Gang,Liu, Sen,Shen, Guodong,Yang, Bingchuan,Zhang, Yalin
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p. 118 - 122
(2022/01/19)
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- 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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p. 1804 - 1808
(2021/03/08)
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- Remarkably Efficient Iridium Catalysts for Directed C(sp2)-H and C(sp3)-H Borylation of Diverse Classes of Substrates
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Here we describe the discovery of a new class of C-H borylation catalysts and their use for regioselective C-H borylation of aromatic, heteroaromatic, and aliphatic systems. The new catalysts have Ir-C(thienyl) or Ir-C(furyl) anionic ligands instead of the diamine-type neutral chelating ligands used in the standard C-H borylation conditions. It is reported that the employment of these newly discovered catalysts show excellent reactivity and ortho-selectivity for diverse classes of aromatic substrates with high isolated yields. Moreover, the catalysts proved to be efficient for a wide number of aliphatic substrates for selective C(sp3)-H bond borylations. Heterocyclic molecules are selectively borylated using the inherently elevated reactivity of the C-H bonds. A number of late-stage C-H functionalization have been described using the same catalysts. Furthermore, we show that one of the catalysts could be used even in open air for the C(sp2)-H and C(sp3)-H borylations enabling the method more general. Preliminary mechanistic studies suggest that the active catalytic intermediate is the Ir(bis)boryl complex, and the attached ligand acts as bidentate ligand. Collectively, this study underlines the discovery of new class of C-H borylation catalysts that should find wide application in the context of C-H functionalization chemistry.
- Chattopadhyay, Buddhadeb,Hassan, Mirja Md Mahamudul,Hoque, Md Emdadul
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supporting information
p. 5022 - 5037
(2021/05/04)
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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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- Efficient Imine Formation by Oxidative Coupling at Low Temperature Catalyzed by High-Surface-Area Mesoporous CeO2 with Exceptional Redox Property
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High-surface-area mesoporous CeO2 (hsmCeO2) was prepared by a facile organic-template-induced homogeneous precipitation process and showed excellent catalytic activity in imine synthesis in the absence of base from primary alcohols and amines in air atmosphere at low temperature. For comparison, ordinary CeO2 and hsmCeO2 after different thermal treatments were also investigated. XRD, N2 physisorption, UV-Raman, H2 temperature-programmed reduction, O2 temperature-programmed desorption, EPR spectroscopy, and X-ray photoelectron spectroscopy were used to unravel the structural and redox properties. The hsmCeO2 calcined at 400 °C shows the highest specific surface area (158 m2 g?1), the highest fraction of surface coordinatively unsaturated Ce3+ ions (18.2 %), and the highest concentration of reactive oxygen vacancies (2.4×1015 spins g?1). In the model reaction of oxidative coupling of benzyl alcohol and aniline, such an exceptional redox property of the hsmCeO2 catalyst can boost benzylideneaniline formation (2.75 and 5.55 mmol (Formula presented.) h?1 based on >99 % yield at 60 and 80 °C, respectively) in air with no base additives. It can also work effectively at a temperature of 30 °C and in gram-scale synthesis. These are among the best results for all benchmark ceria catalysts in the literature. Moreover, the hsmCeO2 catalyst shows a wide scope towards primary alcohols and amines with good to excellent yield of imines. The influence of reaction parameters, the reusability of the catalyst, and the reaction mechanism were investigated.
- Wu, Shipeng,Wang, Yinghao,Cao, Qiue,Zhao, Qihua,Fang, Wenhao
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supporting information
p. 3019 - 3028
(2020/12/11)
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- Efficient imine synthesisviaoxidative coupling of alcohols with amines in an air atmosphere using a mesoporous manganese-zirconium solid solution catalyst
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Direct oxidative coupling of alcohols with amines using a non-precious metal oxide catalyst under mild conditions is highly desirable for imine synthesis. In this work, a mesoporous Mn1ZrxOysolid solution catalyst prepared by a co-precipitation method showed excellent catalytic performance in imine synthesis from primary alcohols and amines without base additives in an air atmosphere. XRD, N2physisorption, H2-TPR, O2-TPD, EPR and XPS were comprehensively used to unravel its structural, redox and amphoteric properties that closely depended on the interaction between MnOyand ZrO2with a variable Zr ratio. The Mn1Zr0.5Oycatalyst presented the highest fractions of Mn3+ions and reactive oxygen species on the surface, and the highest concentrations of acidic-basic sites, which were disclosed to play important roles in activating alcohols and molecular O2in the rate-determining step. In the model reaction of oxidative coupling of benzyl alcohol with aniline, such enhanced features of the Mn1Zr0.5Oycatalyst can promote the intrinsic catalytic activity (iTOF of 1.87 h?1) and boost benzylideneaniline formation (5.56 mmol gcat.?1h?1) based on a >99% yield at 80 °C respectively at a fast response. It can also work effectively at a room temperature of 30 °C, as well as for the gram-grade synthesis. This is one of the best results among all the MnOy-based catalysts in the literature. Moreover, this catalyst showed good stability and a wide substrate scope with good to excellent yields of imines.
- Wu, Shipeng,Zhang, Hao,Cao, Qiue,Zhao, Qihua,Fang, Wenhao
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p. 810 - 822
(2021/02/26)
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- Convenient fabrication of carbon doped WO3?x ultrathin nanosheets for photocatalytic aerobic oxidation of amines
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It is an important chemical transformation for oxidation of amines to imines, on account of very important versatile applications of imines in organic synthesis. Here, we develop a convenient way to synthesize carbon doped WO3?x ultrathin nanos
- Bao, Keyan,Zhang, Shaojie,Ni, Ping,Zhang, Zixiang,Zhang, Kailong,Wang, Liangbiao,Sun, Li Xia,Mao, Wutao,Zhou, Quanfa,Qian, Yitai
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p. 311 - 317
(2018/11/23)
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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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- Cross dehydrogenative coupling strategy for allylation of benzylanilines promoted by DDQ
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A cross dehydrogenative coupling strategy for allylation of benzylanilines promoted by DDQ is reported, which uses nonmetallic quinone DDQ as an oxidant in the allylation of N-benzylanilines under mild conditions. C–C bond with high selectivity and activity was constructed in this reaction and homoallylic amines were obtained with yields of up to 99%.
- Xiong, Ruimei,Hussain, Muhammad Ijaz,Liu, Qing,Xia, Wen,Xiong, Yan
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supporting information
(2019/12/11)
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- Tert-Butyl Hydroperoxide-Mediated Oxo-Sulfonylation of 2 H-Indazoles with Sulfinic Acid toward Indazol-3(2 H)-ones
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A new and efficient oxo-sulfonylation protocol has been established for the synthesis of N-sulfonylated indazolones employing sulfinic acid as a sulfonylating agent using tert-butyl hydroperoxide (TBHP) under ambient air. A series of structurally diverse 1-sulfonylindazol-3(2H)-one derivatives were obtained in good yields. A radical reaction mechanism has been proposed for this transformation.
- Ghosh, Payel,Mondal, Susmita,Hajra, Alakananda
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p. 1086 - 1090
(2020/02/04)
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- Diastereodivergent [3 + 2] Annulation of Aromatic Aldimines with Alkenes via C-H Activation by Half-Sandwich Rare-Earth Catalysts
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Stereodivergent catalysis is of great importance, as it can allow efficient access to all possible stereoisomers of a given product with multiple stereocenters from the same set of starting materials. We report herein the first diastereodivergent [3 + 2]
- Cong, Xuefeng,Hou, Zhaomin,Mo, Zhenbo,Nishiura, Masayoshi,Zhan, Gu
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supporting information
p. 5531 - 5537
(2020/04/09)
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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
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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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- Designed Synthesis of a 2D Porphyrin-Based sp2 Carbon-Conjugated Covalent Organic Framework for Heterogeneous Photocatalysis
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The construction of stable covalent organic frameworks (COFs) for various applications is highly desirable. Herein, we report the synthesis of a novel two-dimensional (2D) porphyrin-based sp2 carbon-conjugated COF (Por-sp2c-COF), whi
- Chen, Rufan,Shi, Ji-Long,Ma, Yuan,Lin, Guiqing,Lang, Xianjun,Wang, Cheng
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supporting information
p. 6430 - 6434
(2019/04/10)
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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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- Visible-light-induced regioselective cross-dehydrogenative coupling of 2 H-indazoles with ethers
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A visible-light-promoted regioselective C(sp2)-H/C(sp3)-H cross-dehydrogenative coupling between 2H-indazoles and ethers has been achieved using a catalytic amount of rose bengal as an organophotoredox-catalyst and tert-butyl hydroperoxide (TBHP) as an oxidant at ambient temperature under aerobic conditions. A variety of C-3 oxyalkylated 2H-indazoles have been synthesized in moderate to good yields. Mechanistic studies suggest a radical pathway of the present reaction.
- Singsardar, Mukta,Laru, Sudip,Mondal, Susmita,Hajra, Alakananda
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p. 4543 - 4550
(2019/04/30)
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- Dual Role of Doubly Reduced Arylboranes as Dihydrogen- and Hydride-Transfer Catalysts
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Doubly reduced 9,10-dihydro-9,10-diboraanthracenes (DBAs) are introduced as catalysts for hydrogenation as well as hydride-transfer reactions. The required alkali metal salts M2[DBA] are readily accessible from the respective neutral DBAs and Li metal, Na metal, or KC8. In the first step, the ambiphilic M2[DBA] activate H2 in a concerted, metal-like fashion. The rates of H2 activation strongly depend on the B-bonded substituents and the counter cations. Smaller substituents (e.g., H, Me) are superior to bulkier groups (e.g., Et, pTol), and a Mes substituent is even prohibitively large. Li+ ions, which form persistent contact ion pairs with [DBA]2-, slow the H2-addition rate to a higher extent than more weakly coordinating Na+/K+ ions. For the hydrogenation of unsaturated compounds, we identified Li2[4] (Me substituents at boron) as the best performing catalyst; its substrate scope encompasses Ph(H)CNtBu, Ph2CCH2, and anthracene. The conversion of E-Cl to E-H bonds (E = C, Si, Ge, P) was best achieved by using Na2[4]. The latter protocol provides facile access also to Me2Si(H)Cl, a most important silicone building block. Whereas the H2-transfer reaction regenerates the dianion [4]2- and is thus immediately catalytic, the H--transfer process releases the neutral 4, which has to be recharged by Na metal before it can enter the cycle again. To avoid Wurtz-type coupling of the substrate, the reduction of 4 must be performed in the absence of the element halide, which demands an alternating process management (similar to the industrial anthraquinone process).
- Von Grotthuss, Esther,Prey, Sven E.,Bolte, Michael,Lerner, Hans-Wolfram,Wagner, Matthias
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supporting information
(2019/04/17)
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- Dual Role of Doubly Reduced Arylboranes as Dihydrogen- and Hydride-Transfer Catalysts
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Doubly reduced 9,10-dihydro-9,10-diboraanthracenes (DBAs) are introduced as catalysts for hydrogenation as well as hydride-transfer reactions. The required alkali metal salts M2[DBA] are readily accessible from the respective neutral DBAs and Li metal, Na metal, or KC8. In the first step, the ambiphilic M2[DBA] activate H2 in a concerted, metal-like fashion. The rates of H2 activation strongly depend on the B-bonded substituents and the counter cations. Smaller substituents (e.g., H, Me) are superior to bulkier groups (e.g., Et, pTol), and a Mes substituent is even prohibitively large. Li+ ions, which form persistent contact ion pairs with [DBA]2-, slow the H2-addition rate to a higher extent than more weakly coordinating Na+/K+ ions. For the hydrogenation of unsaturated compounds, we identified Li2[4] (Me substituents at boron) as the best performing catalyst; its substrate scope encompasses Ph(H)C=NtBu, Ph2C=CH2, and anthracene. The conversion of E-Cl to E-H bonds (E = C, Si, Ge, P) was best achieved by using Na2[4]. The latter protocol provides facile access also to Me2Si(H)Cl, a most important silicone building block. Whereas the H2-transfer reaction regenerates the dianion [4]2- and is thus immediately catalytic, the H--transfer process releases the neutral 4, which has to be recharged by Na metal before it can enter the cycle again. To avoid Wurtz-type coupling of the substrate, the reduction of 4 must be performed in the absence of the element halide, which demands an alternating process management (similar to the industrial anthraquinone process).
- Von Grotthuss, Esther,Prey, Sven E.,Bolte, Michael,Lerner, Hans-Wolfram,Wagner, Matthias
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supporting information
p. 6082 - 6091
(2019/04/17)
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- Readily Available Primary Aminoboranes as Powerful Reagents for Aldimine Synthesis
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Primary aminoboranes (RNHBR2), which are readily available by spontaneous dehydrocoupling of amines and boranes cleanly react at room temperature with aldehydes to give aldimines. The overall transformation from amines to aldimines can be conveniently performed by a sequential one-pot reaction. This synthetic strategy is especially useful for electron poor and bulky amines which are reluctant to react with aldehydes under dehydration conditions. Using a Glorius robustness screen, we show that this methodology is chemoselective, and functional group tolerant. Computational and experimental data support the irreversible formation of the aldimine product in marked contrast with traditional methods.
- Junor, Glen P.,Romero, Erik A.,Chen, Xi,Jazzar, Rodolphe,Bertrand, Guy
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supporting information
p. 2875 - 2878
(2019/02/13)
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- Efficient imine synthesis from oxidative coupling of alcohols and amines under air atmosphere catalysed by Zn-doped Al2O3 supported Au nanoparticles
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Direct oxidative coupling of alcohols and amines is regarded as an effective and green approach for imine synthesis under mild conditions. In this work, Zn-doped γ-Al2O3 supported Au nanoparticles was demonstrated as highly active and selective heterogeneous catalyst for a series of imine productions with good to excellent yields, from alcohols and amines via direct oxidative coupling under air atmosphere without extra base additives. Various physicochemical techniques, including ICP-MS, XRD, N2 physisorption, TEM, XPS and CO2-/NH3-TPD, were used to study the properties of the catalysts. Well-dispersed Au0 nanoparticles with a mean size of ca. 2.9 nm were found highly effective in activating alcohols in the presence of reactive amines. The amount of Zn2+ dopant and the calcination temperature of support during catalyst preparation showed crucial impact on tuning the intrinsic activity for oxidation of benzyl alcohol to benzaldehyde (i.e., the rate-determining step for the model reaction), which was disclosed to be related with the active surface oxygen species and the acidic-basic property of support. The 0.4% Au/Zn0.02Al2O3 catalyst calcined at 400 °C exhibited the highest TOF (39.1 h?1) at 60 °C based on a >99% yield to benzylideneaniline among all the ever-reported Au-based catalysts. Moreover, this catalyst could afford 98% yield to benzylideneaniline at only 30 °C and work effectively for the gram-scale synthesis. It also showed considerable stability after five consecutive recycling.
- Wu, Shipeng,Sun, Weixiao,Chen, Junjie,Zhao, Jinghan,Cao, Qiue,Fang, Wenhao,Zhao
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p. 110 - 121
(2019/08/01)
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- One-pot synthesis of Pd-promoted Ce-Ni mixed oxides as efficient catalysts for imine production from the direct: N -alkylation of amine with alcohol
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Ce-Ni mixed oxides with different Ni/Ce molar ratios, promoted by a rather low amount of Pd (0.2 wt%), were prepared by a simple one-pot precipitation method. The thus-synthesized CeNiXOY and Pd-CeNiXOY catalysts were applied respectively to the direct N-alkylation of amine and alcohol via oxidative coupling, under O2 in the absence of basic additives. The CeNiXOY catalyst could provide a >99% yield of imine in the model alkylation reaction of aniline with benzyl alcohol at 100 °C. The Pd-promoted Pd-CeNiXOY catalyst surprisingly showed an enhanced imine yield (>99%) at a mild temperature of 60 °C. This catalyst exhibited good reusability, and moreover, demonstrated high performance towards imine synthesis from various amines with alcohols. The presence of Pd species and the Ni/Ce molar ratio showed a synergistic impact on the conversion of aniline, as well as on the product selectivity, which was believed to be related to the improvement on the intrinsic activity of the oxidation of benzyl alcohol to benzaldehyde. Various physicochemical techniques, including ICP-MS, XRD, N2 adsorption-desorption, UV-Raman, H2-TPR, TEM, EPMA and XPS, were employed to study mainly the composition, structure and redox properties of the catalysts. The proportion of Ce3+ species and oxygen vacancies, which can be manipulated by the Ce-Ni redox system and the interaction between Ce and Ni, was crucial to the selective activation of alcohols in the presence of reactive amines. The activation of alcohol on the highly reactive Pd0 species was the other crucial factor.
- Zhang, Mengyuan,Wu, Shipeng,Bian, Longchun,Cao, Qiue,Fang, Wenhao
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p. 286 - 301
(2019/01/28)
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- CO2-Catalyzed Efficient Dehydrogenation of Amines with Detailed Mechanistic and Kinetic Studies
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CO2-catalyzed dehydrogenation of amines has been achieved under photocatalytic conditions. With this concept, various amines have been selectively dehydrogenated to the corresponding imines in the presence of different functional groups such as nitrile, nitro, ester, halogen, ether, thioether, and carbonyl or carboxylic acid moieties. At the end, the CO2-catalyzed synthesis of pharmaceutical drugs has been achieved. The CO2 radical has been detected by EPR spectroscopy using DMPO, and the mechanism of this reaction is proposed on the basis of DFT calculations and experimental evidence.
- Riemer, Daniel,Schilling, Waldemar,Goetz, Anne,Zhang, Yu,Gehrke, Sascha,Tkach, Igor,Hollóczki, Oldamur,Das, Shoubhik
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p. 11679 - 11687
(2018/11/23)
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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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- 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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- Unusually Reactive Cyclic Anhydride Expands the Scope of the Castagnoli-Cushman Reaction
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In the course of synthesizing and testing various "azole-including" cyclic anhydrides in the Castagnoli-Cushman reaction with imines, a remarkably reactive, pyrrole-based anhydride has been identified. It displayed a remarkably efficient reaction with N-alkyl and N-aryl imines, in particular, with "enolizable" α-C-H imines which typically fail to react with a majority of known cyclic anhydrides. The reactivity of this anhydride has been justified by an efficient resonance stabilization of its enol form. This finding expands the existing arsenal of highly reactive cyclic anhydrides and further confirms the importance of anhydride enolization for an efficient Castagnoli-Cushman reaction.
- Chizhova, Maria,Khoroshilova, Olesya,Dar'In, Dmitry,Krasavin, Mikhail
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p. 12722 - 12733
(2018/10/15)
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- Conversion of aldimines to secondary amines using iron-catalysed hydrosilylation
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Iron-catalyzed hydrosilylation of imines to amines using a well-defined iron complex is reported. This method employs relatively mild conditions, by reaction of imine, (EtO)3SiH in a 1 : 2 ratio in the presence of 1 mol% precatalyst ([BIAN]Fe(η6-toluene), 3, BIAN = bis(2,6-diisopropylaniline)acenaphthene) at 70 °C. A broad scope of imines was readily converted into the corresponding secondary amines without the need for precatalyst activators.
- Saini, Anu,Smith, Cecilia R.,Wekesa, Francis S.,Helms, Amanda K.,Findlater, Michael
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supporting information
p. 9368 - 9372
(2019/01/03)
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- Robust porous organic polymers as efficient heterogeneous organo-photocatalysts for aerobic oxidation reactions
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Metal-free, visible-light active and heterogeneous organic photocatalysts offer a more sustainable and environmentally friendly alternative to traditional metal-based catalysts. Here a porous organic hyper-crosslinked polymer, CF-HCP, was successfully syn
- Zhi, Yongfeng,Li, Kun,Xia, Hong,Xue, Ming,Mu, Ying,Liu, Xiaoming
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p. 8697 - 8704
(2017/07/10)
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- A Metal-Free Approach to 1,2-Diamines via Visible Light-Driven Reductive Coupling of Imines with Perylene as a Photoredox Catalyst
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A simple, metal-free, and versatile approach to 1,2-diamines has been developed based on reductive coupling reactions of various imines, where perylene, an aromatic hydrocarbon, was used as a photoredox catalyst under visible light irradiation using a white light-emitting diode. The use of 1 mol % perylene enabled almost complete conversion of the imines, leading to the formation of their corresponding 1,2-diamines, which were isolated in good yields. The ratios between dl and meso diamines ranged from 31:69 to 82:18 depending on the substituents of the imines.
- Okamoto, Shusuke,Ariki, Risako,Tsujioka, Hiroki,Sudo, Atsushi
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p. 9731 - 9736
(2017/09/23)
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- Model beta - adrenergic receptor agonist universal hapten synthesis and application of (by machine translation)
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The present invention has offered a kind of beta - adrenergic receptor agonist universal hapten synthetic method and its application. The universal hapten with beta - adrenergic receptor agonists of common structure, can be used for preparing has the responsibility of broad spectrum beta - adrenergic receptor agonist antibody. The invention also relates to the general hapten in the synthesis intermediate for, and the general hapten preparation wide spectrum response of the marker antibody, including colloidal gold label, enzyme marker and fluorescent dye label. (by machine translation)
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Paragraph 0018
(2017/12/05)
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- Synthesis of 4-Isoxazolines via Visible-Light Photoredox-Catalyzed [3 + 2] Cycloaddition of Oxaziridines with Alkynes
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A method for [3 + 2] cycloaddition of oxaziridines with alkynes to form 4-isoxazolines via visible-light photoredox catalysis is described. This method is a greener, atom-economical reaction that tolerates various functional groups and provides good to excellent yield. Moreover, the cyclization products can be conveniently converted into tetrasubstituted allylic alcohols and enamines. A mechanistic study suggests that the reaction involves photoredox-catalyzed in situ generation of a nitrone from the oxaziridine by SET.
- Jang, Gwang Seok,Lee, Junggeun,Seo, Jungseok,Woo, Sang Kook
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supporting information
p. 6448 - 6451
(2017/12/08)
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- Triggered and Tunable Hydrogen Sulfide Release from Photogenerated Thiobenzaldehydes
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Hydrogen sulfide (H2S) has been identified as an important cell-signaling mediator and has a number of biological functions, such as vascular smooth muscle relaxation, neurotransmission, and regulation of inflammation. A facile and versatile approach for H2S production initiated by light irradiation and controlled by reaction with an amine or an amino acid was developed. The donor was synthesized in a one-pot reaction, and simple crystallization led to a yield of approximately 90 %. The synthetic strategy is scalable and versatile, and the H2S donors can be expressed ina number of different molecular and macromolecular forms, including crystalline small-molecule compounds, water-soluble polymers, polystyrene films, and hydrogels. The H2S donors based on polystyrene film and hydrogel were used as cell-culture scaffolds. The H2S donor based on water-soluble polymer was applied in photocontrolled inhibition of P-selectin expression on human platelets and subsequent regulation of platelet aggregation. This study provides the simplest controllable H2S source to study its biological functions. The developed materials are also new therapeutic platforms to deliver H2S, as there is no accumulation of toxic byproducts, and the donor materials from polystyrene films and hydrogels can be readily removed after releasing H2S.
- Xiao, Zeyun,Bonnard, Thomas,Shakouri-Motlagh, Aida,Wylie, Ross A. L.,Collins, Joe,White, Jonathan,Heath, Daniel E.,Hagemeyer, Christoph E.,Connal, Luke A.
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p. 11294 - 11300
(2017/08/26)
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- Ruthenium Bisammine Complex and Its Reaction with Aryl Azides
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A ruthenium bisammine complex was formed in the reaction of ruthenium 1,4-dibenzyltetraazadiene complex with primary amines at room temperature, which was a versatile precursor for the synthesis of various Ru(II) complexes through ligand exchange reactions. In the reaction with azidobenzene, ruthenium 1,4-diphenyltetraaza-1,3-diene complex was formed, while ruthenium imido complexes were given in the reaction with bulky aryl azides such as 2-azido-1,3-dimethylbenzene and 2-azido-1,3-diisopropylbenzene. The ruthenium imido complexes showed high catalytic activity in the reaction of alkyl azides with primary amines to afford N-substituted imines.
- Park, Jin Yong,Kim, Yongjin,Bae, Dae Young,Rhee, Young Ho,Park, Jaiwook
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p. 3471 - 3476
(2017/10/03)
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- Well-Defined Silica Grafted Molybdenum Bis(imido) Catalysts for Imine Metathesis Reactions
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Novel site-isolated tetracoordinated molybdenum complexes possessing bis(imido) ligands, [( - Si-O)2Mo( - NR)2] (R = t-Bu, 2,6-C6H3-i-Pr2), were immobilized on partially dehydroxylated silica (SiO2-200) by a rigorous surface organometallic chemistry protocol. The newly developed materials adorned with bis(imido) functional units, which were previously exploited mainly as spectator ligands on silica-supported olefin metathesis molybdenum catalysts, are found to be efficient heterogeneous catalytic systems for imine cross metathesis under mild conditions.
- Barman, Samir,Merle, Nicolas,Minenkov, Yury,De Mallmann, Aimery,Samantaray, Manoja K.,Le Quéméner, Frédéric,Szeto, Kai C.,Abou-Hamad, Edy,Cavallo, Luigi,Taoufik, Mostafa,Basset, Jean-Marie
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supporting information
p. 1550 - 1556
(2017/04/28)
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- Homologation of α-aryl amino acids through quinone-catalyzed decarboxylation/Mukaiyama-Mannich addition
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A new method for amino acid homologation by way of formal C-C bond functionalization is reported. This method utilizes a 2-step/1-pot protocol to convert α-amino acids to their corresponding N-protected β-amino esters through quinone-catalyzed oxidative decarboxylation/in situ Mukaiyama-Mannich addition. The scope and limitations of this chemistry are presented. This methodology provides an alternative to the classical Arndt-Eistert homologation for accessing β-amino acid derivatives. The resulting N-protected amine products can be easily deprotected to afford the corresponding free amines.
- Haugeberg, Benjamin J.,Phan, Johnny H.,Liu, Xinyun,O'Connor, Thomas J.,Clift, Michael D.
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supporting information
p. 3062 - 3065
(2017/03/17)
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- Silica functionalized Cu(II) acetylacetonate Schiff base complex: An efficient catalyst for the oxidative condensation reaction of benzyl alcohol with amines
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Silica functionalized Cu(II) acetylacetonate Schiff base complex via the one pot reaction of silica functionalized 3-aminopropyltriethoxysilane with acetyl acetone and copper acetate has been reported. The synthesized material was well characterized by analytical techniques such as FT-IR, UV-DRS, XRD, SEM-EDX, HR-TEM, EPR, ICP-AES and BET analysis. The characterization results confirmed the grafting of Cu(II) Schiff base complex on the silica surface. The catalytic activity of synthesized silica functionalized Cu(II) acetylacetonate Schiff base complex was evaluated through the oxidative condensation reaction of benzyl alcohol to imine.
- Anbarasu,Malathy,Karthikeyan,Rajavel
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p. 305 - 312
(2017/06/27)
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- A metallopeptoid as an efficient bioinspired cooperative catalyst for the aerobic oxidative synthesis of imines
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Enzymatic catalysis is largely based on intramolecular cooperativity between a metal center and functional organic molecules located on one scaffold. Inspired by this concept we have designed the metallopeptoid trimer BT, which is a unique intramolecular cooperative oxidation catalyst incorporating two catalytic centers, phenanthroline-copper and TEMPO, as well as one non-catalytic benzyl group. Herein we explore the capability of BT to act as an efficient catalyst for the oxidative synthesis of imines, which are versatile intermediates in the fine chemicals and pharmaceutical industries. We demonstrate that BT, combined with CuI, can catalyze the production of benzyl, aryl, heteroaryl, allylic and aliphatic imines from various alcohols and amines with a turn-over-number up to 45 times higher than this achieved when phenanthroline, copper and TEMPO are mixed in solution. Moreover, in low catalyst(s) loading, BT enables transformations that are not possible when a mixture of the individual catalysts is employed.
- Chandra Mohan, Darapanani,Sadhukha, Arghya,Maayan, Galia
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p. 139 - 144
(2017/10/16)
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- Quinone-catalyzed oxidative deformylation: Synthesis of imines from amino alcohols
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A new method for imine synthesis by way of quinone-catalyzed oxidative deformylation of 1, 2-amino alcohols is reported. A wide range of readily accessible amino alcohols and primary amines can be reacted to provide N-protected imine products. The methodology presented provides a novel organocatalytic approach for imine synthesis and demonstrates the synthetic versatility of quinone-catalyzed oxidative C-C bond cleavage.
- Liu, Xinyun,Phan, Johnny H.,Haugeberg, Benjamin J.,Londhe, Shrikant S.,Clift, Michael D.
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supporting information
p. 2895 - 2901
(2018/01/17)
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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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- Structure-Reactivity Relationship in the Frustrated Lewis Pair (FLP)-Catalyzed Hydrogenation of Imines
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The autoinduced, frustrated Lewis pair (FLP)-catalyzed hydrogenation of 16-benzene-ring substituted N-benzylidene-tert-butylamines with B(2,6-F2C6H3)3 and molecular hydrogen was investigated by kinetic analysis. The pKa values for imines and for the corresponding amines were determined by quantum-mechanical methods and provided a direct proportional relationship. The correlation of the two rate constants k1 (simple catalytic cycle) and k2 (autoinduced catalytic cycle) with pKa difference between imine and amine pairs (ΔpKa) or Hammett's σ parameter served as useful parameters to establish a structure-reactivity relationship for the FLP-catalyzed hydrogenation of imines.
- Tussing, Sebastian,Kaupmees, Karl,Paradies, Jan
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supporting information
p. 7422 - 7426
(2016/05/24)
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- Preparation of Secondary Phosphine Oxide Ligands through Nucleophilic Attack on Imines and Their Applications in Palladium-Catalyzed Catellani Reactions
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Several new amino-type secondary phosphine oxide (SPO) pre-ligands (3a–3h) that contain P–N bonds were synthesized and characterized. SPOs 3a–3h can tautomerize to phosphinous acids (PA, 3a–3h) as genuine ligands. The formation of SPOs 3a–3h occurred first through nucleophilic attack on the imine carbon atom, then by the addition of RPCl2(R = Ph, Cy, tBu, or iPr), and work-up under acidic conditions. The P–N bond in the newly prepared SPOs is evident from the crystal structures of SPOs 3d and 3h. Reactions of SPOs 3f, 3g, or 3h with Pd(COD)Cl2(COD = cyclooctadiene) yielded palladium complexes 6f, 6g, or 6h. In these crystal structures, PAs 3f, 3g, and 3h act as didentate ligands through P and N donors. Intriguingly, the reaction of SPO 3f with Pd(COD)Cl2also gave rise to palladium complexes 7fa, 7fb, and 8f. The crystal structures of 7fa and 7fb show that the palladium atom is chelated by PA 3f and coordinated by a phosphine-like ligand fragmented from SPO 3f through C–N bond dissociation. Finally, the syntheses of carbazole derivatives were pursued in Catellani reactions with SPOs 3g and 3h as pre-ligands. A mechanism is proposed to account for the catalytic reaction (see the Supporting Information). The optimized conditions for Suzuki reactions using selected SPO ligands are also reported.
- Hu, Chan-Yu,Chen, Ya-Qian,Lin, Guan-Yu,Huang, Ming-Kai,Chang, Yu-Chang,Hong, Fung-E
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p. 3131 - 3142
(2016/07/14)
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- Asymmetric induction in the addition of enantiomerically pure H-phosphinate to chiral aldimines: diastereoselective generation of α-amino phosphinates with P,C-stereogenic centers
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α-Amino phosphinates with P,C-stereogenic centers were prepared from a P-retained addition of (RP)-(?)-menthyl H-phenylphosphinate to (R)-aldimines with up to 86:14 dr under catalyst and solvent free condition at ambient temperature; the single
- Yang, Meng,Xu, Hao,Zhou, Zhong-Yang,Zhang, He,Liu, Li-Juan,Sun, Yong-Ming,Nie, Shao-Zhen,Zhao, Chang-Qiu
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supporting information
p. 815 - 822
(2016/09/02)
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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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- Combination of Enabling Technologies to Improve and Describe the Stereoselectivity of Wolff-Staudinger Cascade Reaction
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A new, single-mode bench-top resonator was evaluated for the microwave-assisted flow generation of primary ketenes by thermal decomposition of α-diazoketones at high temperature. A number of amides and β-lactams were obtained by ketene generation in situ and reaction with amines and imines, respectively, in good to excellent yields. The preferential formation of trans-configured β-lactams was observed during the [2+2] Staudinger cycloaddition of a range of ketenes with different imines under controlled reaction conditions. Some insights into the mechanism of this reaction at high temperature are reported, and a new web-based molecular viewer, which takes advantage from Augmented Reality (AR) technology, is also described for a faster interpretation of computed data.
- Musio,Mariani,?liwiński,Kabeshov,Odajima,Ley
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supporting information
p. 3515 - 3526
(2016/10/18)
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- Metal-free aerobic oxidative coupling of amines in dimethyl sulfoxide via a radical pathway
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Metal-free oxidative coupling of amines is achieved simply by heating their dimethyl sulfoxide (DMSO) solution under oxygen as oxidant without any other catalysts or additives, accompanied by the formation of an equimolar amount of dimethyl sulfone (DMSO2). EPR experiments indicate that the reaction proceeds via a radical pathway. DMSO may play a triple role as solvent, radical initiator and co-reductant.
- Lin, Mu,Wang, Zikuan,Fang, Huayi,Liu, Lianghui,Yin, Haolin,Yan, Chun-Hua,Fu, Xuefeng
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p. 10861 - 10864
(2016/02/05)
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- Isomerization method for bis(amino-methyl)cyclohexane
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An isomerization method for bis(amino-methyl)cyclohexane has an isomerization step for isomerizing bis(amino-methyl)cyclohexane in the presence of an imine compound represented by general formula (1) and one or more type of compound selected from the group comprising an alkali metal, an alkali-metal-containing compound, an alkali earth metal, and an alkali-earth-metal-containing compound. (In general formula (1), R1 and R2 each independently indicates a monovalent group selected from the group comprising a hydrogen atom, a substituted or un-substituted hydrocarbon group, a substituted or un-substituted alkoxy group, and an acyl group. (R1 and R2 may be bonded to each other and form a ring.) R3 indicates an n-valent group selected from the group comprising a hydrogen atom and a substituted or un-substituted hydrocarbon group, n being an integer from 1 to 10.).
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Paragraph 0253; 0254; 0255
(2016/10/10)
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- Well-defined BiOCl colloidal ultrathin nanosheets: Synthesis, characterization, and application in photocatalytic aerobic oxidation of secondary amines
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We demonstrate the first colloidal synthesis of single-crystalline BiOCl ultrathin nanosheets (UTNSs) that feature a well-defined square morphology. Unlike BiOCl nanomaterials prepared by hydrothermal routes, our colloidal BiOCl UTNSs exhibit hydrophobic
- Wu, Yihui,Yuan, Bo,Li, Mingrun,Zhang, Wen-Hua,Liu, Yan,Li, Can
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p. 1873 - 1878
(2015/06/15)
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- Tris(dialkylamide)aluminum compound, and method for producing aluminum-containing thin film using same
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The present invention relates to a tris(dialkylamide)aluminum compound, and a method for producing an aluminum-containing thin film using the aluminum compound, the tris(dialkylamide)aluminum compound being represented by the formula (1): wherein R represents a linear alkyl group having 1 to 6 carbon atoms; andR1, R2 and R3 may be the same as, or different from each other, and each independently represents hydrogen atom, or a linear or branched alkyl group having 1 to 6 carbon atoms, or R1, R2 and R3 may be joined together to form a ring, with the proviso that the compounds in which two or more of R1, R2 and R3 are hydrogen atoms are excluded, and three dialkylamide ligands may be the same as, or different from each other.
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Page/Page column 22
(2015/12/05)
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