- 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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- Cobalt-catalyzed carbonylation of N-alkylbenzaldimines to 'N-alkylphthalimidines' (=2,3-dihydro-1H-isoindol-1-ones) via tandem C-H activation and cyclocarbonylation
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The reaction of N-alkylbenzaldimines with carbon monoxide (CO) in the presence of cobalt (Co) catalysts resulted in the formation of N-alkylphthalimidines (Table 1). Their formation is proposed to occur by C-H activation of the aryl ring, migratory insertion of the hydride species into the benzaldimine functionality, CO coordination, and insertion into the Co-C bond, followed by reductive elimination of the N-alkylphthalimidine and regeneration of the starting Co species (Scheme 4). Deuterium (2H)-labeling NMR studies are consistent with this mechanism (Scheme 5).
- Funk, Jeffrey K.,Yennawar, Hemant,Sen, Ayusman
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Read Online
- Photocatalytic Hydrogen Evolution Coupled with Production of Highly Value-Added Organic Chemicals by a Composite Photocatalyst CdIn2S4@MIL-53-SO3Ni1/2
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Photocatalytic water splitting coupled with the production of highly value-added organic chemicals is of significant importance, which represents a very promising pathway for transforming green solar energy into chemical energy. Herein, we report a composite photocatalyst CdIn2S4@MIL-53-SO3Ni1/2, which is highly efficient on prompting water splitting for the production of H2 in the reduction half-reaction and selective oxidation of organic molecules for the production of highly value-added organic chemicals in the oxidation half-reaction under visible light irradiation. The superior photocatalytic properties of the composite photocatalyst CdIn2S4@MIL-53-SO3Ni1/2 should be ascribed to coating suspended ion catalyst (SIC), consisting of redox-active NiII ions in the anionic pores of coordination network MIL-53-SO3?, on the surface of photoactive CdIn2S4, which endows photogenerated electron-hole pairs separate more efficiently for high rate production of H2 and selective production of highly value-added organic products, demonstrating great potential for practical applications.
- Zhang, Huan-Huan,Zhan, Guo-Peng,Liu, Zi-Kun,Wu, Chuan-De
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supporting information
p. 1499 - 1506
(2021/05/06)
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- Design, Synthesis, and Biological Evaluation of Novel 3-Aminomethylindole Derivatives as Potential Multifunctional Anti-Inflammatory and Neurotrophic Agents
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The development of multifunctional molecules that are able to simultaneously interact with several pathological components has been considered as a solution to treat the complex pathologies of neurodegenerative diseases. Herein, a series of aminomethylindole derivatives were synthesized, and evaluation of their application for antineuroinflammation and promoting neurite outgrowth was disclosed. Our initial screening showed that most of the compounds potently inhibited lipopolysaccharide (LPS)-stimulated production of NO in microglial cells and potentiated the action of NGF to promote neurite outgrowth of PC12 cells. Interestingly, with outstanding NO/TNF-α production inhibition and neurite outgrowth-promoting activities, compounds 8c and 8g were capable of rescuing cells after injury by H2O2. Their antineuroinflammatory effects were associated with the downregulation of the LPS-induced expression of the inflammatory mediators inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Western blotting and immunofluorescence assay results indicated that the mechanism of their antineuroinflammatory actions involved suppression of the MAPK/NF-κB signal pathways. Further studies revealed that another important reason for the high comprehensive antineuroinflammatory activity was the anti-COX-2 capabilities of the compounds. All these results suggest that the potential biochemical multifunctional profiles of the aminomethylindole derivatives provide a new sight for the treatment of neurodegenerative diseases.
- Wang, Wei-Wei,Liu, Ting,Lv, Yu-Meng,Zhang, Wu-Yang,Liu, Zhi-Gang,Gao, Jin-Ming,Li, Ding
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p. 1593 - 1605
(2021/05/31)
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- Discovery of tert-amine-based RORγt agonists
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The nuclear receptor retinoic acid receptor-related orphan receptor gamma-t (RORγt) is a transcription factor regulating Th17 cell differentiation and proliferation from naive CD4+ T cells. Since Th17 cells have demonstrated the antitumor efficacy by eliciting remarkable activation of CD8+ T cells, RORγt agonists could be applied as potential small molecule therapeutics for cancer immunotherapy. Based on the previously reported RORγt agonist 1 and its resolved co-crystal structure, a series of new tertiary amines were designed, synthesized and biologically evaluated, yielding optimal moieties with improved chemical properties and biological responses. The combination of these optimal moieties resulted in identification of novel RORγt agonists such as 8b with further elevated RORγt agonism responses at a target-based level as well as in cell-based assays, which provided some structural knowledge for further optimization of RORγt agonists as small molecule therapeutics for cancer immunotherapy.
- Qiu, Ruomeng,Yu, Mingcheng,Gong, Juwen,Tian, Jinlong,Huang, Yafei,Wang, Yonghui,Xie, Qiong
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- Photocatalytic selective aerobic oxidation of amines to nitriles over Ru/γ-Al2O3: The role of the support surface and the strong imine intermediate adsorption
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Hydroxyl coordinated ruthenium dispersed on the surface of γ-Al2O3 can be applied to the selective oxidation of amines with light irradiation and an atmospheric pressure of O2 at room temperature. Sunlight is also an effective light source for the selective aerobic oxidation of primary amines to corresponding nitriles. The high photocatalytic activity and selectivity over Ru/γ-Al2O3 originate from the adsorption of amines and imine intermediates on the abundant surface OH groups of the photocatalyst and further formation of Ru-amide species by ligand exchange of adsorbed amines and imine intermediates with adjacent exposed active Ru sites. Light is introduced to the system successfully via the formation of Ru-amide species, which are used as the light absorption sites of the photocatalytic selective oxidation of amines. Primary amines are directly converted to corresponding nitriles via a two-step oxidative dehydrogenation process.
- Zhu, Pengqi,Zhang, Jin,Wang, Jie,Kong, Peng,Wang, Yunwei,Zheng, Zhanfeng
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p. 440 - 449
(2020/02/04)
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- Photoimmobilized Ni Clusters Boost Photodehydrogenative Coupling of Amines to Imines via Enhanced Hydrogen Evolution Kinetics
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Imines are important precursors for pharmaceutical, agricultural, and synthetic chemistry. The state-of-art synthesis of imines via condensation of amines with aldehydes or ketones often uses homogeneous catalysts and dehydrating agents to promote the elimination of water, which requires huge manpower input for the late-stage purification process and is usually environmentally unfriendly. Photocatalytic synthesis of imines from amines oxidation via the release of hydrogen (H2) is of great promise due to the mild reaction characteristics; however, the efficiency of such a reaction lags due to the missing designed photocatalyst owing to the ambiguous reaction mechanism. Here, we demonstrate that by constructing in situ photoimmobilized Ni clusters on the CdS photocatalyst, the generation of imines is dramatically improved with the rapid release of molecular H2 under visible light illumination. Mechanistic investigation reveals that the adsorption of photogenerated hydrogen atoms during the dehydrogenation of amines is significantly weakened on Ni clusters, thus resulting in fast C-N coupling kinetics for the generation of imines. The photocatalyst presents stable performance with high efficiency. A remarkably apparent quantum efficiency (AQE) of ?44% is realized under 420 nm irradiation for the conversion of 4-methoxybenzylamine within six consecutive runs. Furthermore, a series of primary and secondary amines bearing different functional groups (i.e., heterocyclic, aliphatic, N-heterocycles) that are synthetically challenging by the condensation process can be selectively converted to the corresponding imines, featuring its application prospect.
- Huang, Yi,Li, Huizhi,Li, Mengyang,Li, Yongwang,Liu, Cuibo,Su, Ren,Zhang, Bin
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p. 3904 - 3910
(2020/03/30)
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- Enantioselective Reductive Coupling of Imines Templated by Chiral Diboron
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We herein report a general, practical, and highly efficient method for asymmetric synthesis of a wide range of chiral vicinal diamines via reductive coupling of imines templated by chiral diboron. The protocol features high enantioselectivity and stereospecificity, mild reaction conditions, simple operating procedures, use of readily available starting materials, and a broad substrate scope. The method signifies the generality of diboron-enabled [3,3]-sigmatropic rearrangement.
- Chen, Dongping,Li, Kaidi,Tang, Wenjun,Xu, Guangqing,Xu, Ronghua,Zhou, Mingkang
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supporting information
p. 10337 - 10342
(2020/07/04)
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- Stable carbamate pathway towards organic-inorganic hybrid perovskites and aromatic imines
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Methyl ammonium methyl carbamate (MAC), formulated as CH3NH3+CH3NHCO2-, was synthesized by reacting liquid methylamine with supercritical CO2, and its structure was refined by single-crystal X-ray diffraction. MAC is a white crystalline salt and is as reactive as methylamine, and is a very efficient alternative to toxic methylamine. We were able to produce hybrid perovskite MAPbI3 (MA = methyl ammonium) by grinding MAC with PbI2 and I2 at room temperature, followed by storing the mixed powder. Moreover, this one-pot method is easily scalable for the large-scale synthesis of MAPbI3 in a small vessel. We have also investigated the reactivity of MAC towards aromatic aldehydes in the absence of solvent. The solventless reactions afforded imines as exclusive products with over 97% yield, which show higher selectivity than the methylamine-based synthesis. Complete conversions were typically accomplished within 3 h at 25 °C. The results of this study emphasize the importance of solid carbamates such as MAC to develop an environmentally friendly process for the synthesis of various amine-based materials on the industrial scale.
- Hur, Nam Hwi,Kim, Sun Joo,Lee, Byeongno,Lee, Kyu Hyung,Lim, Byung Wook,Nam, Wonwoo,Park, Hee Sun,Park, Young Jun
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p. 38055 - 38062
(2020/11/02)
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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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- Mechanosynthesis of N-methyl imines using recyclable imidazole-based acid-scavenger: In situ formed ionic liquid as catalyst and dehydrating agent
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1,1′-(1,4-Butanediyl)bis(imidazole) was prepared by a modified method and its application as an efficient promoter was demonstrated for the mechanosynthesis of N-methyl imines using ball milling as a non-conventional process under solvent-free conditions. In this new protocol design, the bis-imidazole acted as a recyclable acid-scavenging agent. This efficient approach to the N-methyl imines displays a combination of the synthetic virtues of a non-conventional condensation reaction with ecological benefits and convenience of a facile mechanosynthetic process. The current method has advantages such as reduced waste by avoiding solvent, exclusion of hazardous materials during the reaction, elimination of handling an anhydrous gas in an evacuated container or a solution of methylamine in ethanol, good yields for relatively unreactive benzaldehydes containing electron-donating substituents, short reaction times, and metal- and acid-free conditions. Furthermore, the promoter was easily regenerated and reused several times with no significant loss of activity.
- Khaligh, Nader Ghaffari,Ling, Ong Chiu,Mihankhah, Taraneh,Johan, Mohd Rafie,Ching, Juan Joon
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p. 194 - 199
(2018/12/04)
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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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- α-Acyl-α-diazoacetates in Transition-Metal-Free β-Lactam Synthesis
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Thermally promoted reaction of α-acyl-α-diazoacetates with imines has been investigated. The transformation, earlier reported predominantly under transition metal catalyzed conditions, delivers α-alkoxycarbonyl-substituted β-lactams with outstanding diastereoselectivity. DFT calculations performed in order to evaluate energetically feasible reaction pathways revealed the intermediacy of 1,3-oxazin-4-one intermediates hitherto never implicated in the Staudinger synthesis of β-lactams.
- Synofzik, Judith,Dar'In, Dmitry,Novikov, Mikhail S.,Kantin, Grigory,Bakulina, Olga,Krasavin, Mikhail
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p. 12101 - 12110
(2019/10/02)
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- A BEt3-Base catalyst for amide reduction with silane
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Reported herein is the development of a simple but practical catalytic system for the selective reduction of amides with hydrosilane or hydrosiloxane. Low-cost and readily available triethylborane (1.0 M in THF), in combination with a catalytic amount of an alkali metal base, was found to catalyze the reduction of all three amide classes (tertiary, secondary, and primary amides) to form amines under mild conditions. In addition, the selective transformation of secondary amides to aldimines and primary amides to nitriles can also be achieved by using a proper combination of BEt3 and base. The scope of these BEt3-base-catalyzed amide hydrosilylation reactions has been explored in depth. Preliminary results of mechanistic studies suggest a modified Piers' silane Si-H···B activation mode wherein the hydride abstraction by BEt3 is promoted by the coordination of an alkoxide or hydroxide anion to the Si center.
- Yao, Wubing,Fang, Huaquan,He, Qiaoxing,Peng, Dongjie,Liu, Guixia,Huang, Zheng
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supporting information
(2019/05/22)
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- Selective oxidation of exogenous substrates by a bis-Cu(III) bis-oxide complex: Mechanism and scope
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Cu(III)2(μ-O)2 bis-oxides (O) form spontaneously by direct oxygenation of nitrogen-chelated Cu(I) species and constitute a diverse class of versatile 2e?/2H+ oxidants, but while these species have attracted attention as biomimetic models for dinuclear Cu enzymes, reactivity is typically limited to intramolecular ligand oxidation, and systems exhibiting synthetically useful reactivity with exogenous substrates are limited. OTMPD (TMPD = N1, N1, N3, N3-tetramethylpropane-1,3-diamine) presents an exception, readily oxidizing a diverse array of exogenous substrates, including primary alcohols and amines selectively over their secondary counterparts in good yields. Mechanistic and DFT analyses suggest substrate oxidation proceeds through initial axial coordination, followed by rate-limiting rotation to position the substrate in the Cu(III) equatorial plane, whereupon rapid deprotonation and oxidation by net hydride transfer occurs. Together, the results suggest the selectivity and broad substrate scope unique to OTMPD are best attributed to the combination of ligand flexibility, limited steric demands, and ligand oxidative stability. In keeping with the absence of rate-limiting C–H scission, OTMPD exhibits a marked insensitivity to the strength of the substrate Cα–H bond, readily oxidizing benzyl alcohol and 1-octanol at near identical rates.
- Large, Tao A.G.,Mahadevan, Viswanath,Keown, William,Stack, T. Daniel P.
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p. 782 - 792
(2019/01/03)
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- Synthesis, Characterization, and Photocatalytic Application of Type-II CdS/Bi2W2O9 Heterojunction Nanomaterials towards Aerobic Oxidation of Amines to Imines
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A series of new type-II CdS/Bi2W2O9 heterojunction nanomaterials is prepared by a two stage process. Initially, phase-pure Bi2W2O9, with orthorhombic crystalline structure, is prepared by a facile combustion-synthesis route. The combustion-synthesized Bi2W2O9 is subsequently modified by CdS nanoparticles using a hydrothermal route. The CdS/Bi2W2O9 heterojunctions are characterized using XRD, XPS, FTIR spectroscopy, UV/Vis DRS, PL, and FESEM and HRTEM studies. The occurrence of ultrafine CdS nanoparticles, with diameters of 8–15 nm, well-dispersed over BWO plates, is inferred from microscopic characterization studies. The two crystalline phases exhibit microscopic close contact across grain boundaries, facilitating the transfer of excitons. The heterojunction materials exhibit improved visible-light absorption, enhanced charge-carrier separation, and suitable band-alignment characteristics of a type-II heterojunction. The CdS/Bi2W2O9 heterojunctions are evaluated as visible-light-active photocatalysts for the aerobic oxidation of amines to imines. Structurally and functionally diverse amine molecules are oxidized to the corresponding imines, with excellent selectivity, in a short span of time.
- Bhoi, Yagna Prakash,Mishra, Braja G.
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p. 2648 - 2658
(2018/06/27)
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- A general and atom-efficient continuous-flow approach to prepare amines, amides and imines via reactive N-chloramines
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Chloramines are an important class of reagents, providing a convenient source of chlorine or electrophilic nitrogen. However, the instability of these compounds is a problem which makes their isolation and handling difficult. To overcome these hazards, a continuous-flow approach is reported which generates and immediately reacts N-chloramines directly, avoiding purification and isolation steps. 2-Chloramines were produced from the reaction of styrenes with N-alkyl-N-sulfonyl-N-chloramines, whilst N-alkyl or N,N’-dialkyl-N-chloramines reacted with anisaldehyde in the presence of t-BuO2H oxidant to afford amides. Primary and secondary imines were produced under continuous conditions from the reaction of N-chloramines with base, with one example subsequently reduced under asymmetric conditions to produce a chiral amine in 94% ee.
- Jolley, Katherine E.,Chapman, Michael R.,John Blacker
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p. 2220 - 2228
(2018/09/04)
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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 0025-0033; 0034; 0038; 0039; 0043; 0044; 0048
(2018/11/22)
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- A General Way to Construct Arene-Fused Seven-Membered Nitrogen Heterocycles
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Imines react with seven-membered cyclic anhydrides (prepared from the corresponding dicarboxylic acids by a recently discovered in-situ cyclodehydration protocol) by the Castagnoli–Cushman reaction pathway to give privileged seven-membered arene-fused nitrogen-heterocyclic compounds with reagent-controlled diversity of the skeleton and peripheral groups.
- Bakulina, Olga,Chizhova, Maria,Dar'in, Dmitry,Krasavin, Mikhail
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p. 362 - 371
(2018/01/27)
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- Synthesis of N-methyl imines in the presence of poly(N-vinylpyridine) as a reusable solid base catalyst by a mechanochemical process
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The synthesis of N-methyl imines was performed in the presence of catalytic amounts of poly(4-vinylpyridine) in high yields and rapidly at room temperature by a ball milling process. This new method has some advantages including good yields for relatively unreactive carbonyl compounds and short reaction times as well as being green in terms of avoiding the use of toxic reagents and solvents. The major advantage of this process is that the catalyst can be easily regenerated and reused several times without any significant loss of activity.
- Khaligh, Nader Ghaffari,Abbo, Hanna S.,Titinchi, Salam J. J.
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p. 901 - 910
(2017/02/10)
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- Beyond the five and six: Evaluation of seven-membered cyclic anhydrides in the castagnoli-cushman reaction
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The Castagnoli-Cushman reaction with benzo[d]- oxepine-2,4(1H,5H)-dione as an anhydride component allowed for preparation of 2,3-disubstituted 4-oxo-2,3,4,5-tetrahydro-1H-benzo[d]- azepine-1-carboxylic acids in 21-75% yields and with good trans diastereoselectivity. The method worked with imines generated from aromatic or a-branched aliphatic aldehydes and is amenable for both parallel synthesis and scale-up. The procedure for epimerization of the resulting trans-disubstituted tetrahydrobenzo[d]azepines to their cis isomers was also developed.
- Adamovskyi, Mykhailo I.,Ryabukhin, Sergey V.,Sibgatulin, Dmitriy A.,Rusanov, Eduard,Grygorenko, Oleksandr O.
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supporting information
p. 130 - 133
(2017/09/08)
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- Cooperative Multifunctional Catalysts for Nitrone Synthesis: Platinum Nanoclusters in Amine-Functionalized Metal–Organic Frameworks
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Nitrones are key intermediates in organic synthesis and the pharmaceutical industry. The heterogeneous synthesis of nitrones with multifunctional catalysts is extremely attractive but rarely explored. Herein, we report ultrasmall platinum nanoclusters (PtNCs) encapsulated in amine-functionalized Zr metal–organic framework (MOF), UiO-66-NH2 (Pt@UiO-66-NH2) as a multifunctional catalyst in the one-pot tandem synthesis of nitrones. By virtue of the cooperative interplay among the selective hydrogenation activity provided by the ultrasmall PtNCs and Lewis acidity/basicity/nanoconfinement endowed by UiO-66-NH2, Pt@UiO-66-NH2 exhibits remarkable activity and selectivity, in comparison to Pt/carbon, Pt@UiO-66, and Pd@UiO-66-NH2. Pt@UiO-66-NH2 also outperforms Pt nanoparticles supported on the external surface of the same MOF (Pt/UiO-66-NH2). To our knowledge, this work demonstrates the first examples of one-pot synthesis of nitrones using recyclable multifunctional heterogeneous catalysts.
- Li, Xinle,Zhang, Biying,Tang, Linlin,Goh, Tian Wei,Qi, Shuyan,Volkov, Alexander,Pei, Yuchen,Qi, Zhiyuan,Tsung, Chia-Kuang,Stanley, Levi,Huang, Wenyu
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supporting information
p. 16371 - 16375
(2017/11/28)
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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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- Four-Electron Electrocyclic Ring-Opening/Intermolecular [4+2] Cycloadditions of α-Hydroxycyclobutenones: Stereoselective Synthesis of Multiple Substituted δ-Lactams
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A four-electron electrocyclic ring-opening/intermolecular [4+2] cycloaddition of α-hydroxycyclobutenones is reported. The reaction represents the first example for the intermolecular cycloaddition of the extensively studied enol-ketene intermediate, and provides a new synthetic route to multiply substituted δ-lactams in high stereoselectivity.
- Song, Peidong,Li, Qing,Wang, Congcong,Wu, Wenfa,Mao, Xu,Wang, Jiajia,Hu, Xiangdong
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supporting information
p. 1208 - 1212
(2016/04/26)
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- Cooperative Lewis Acid/Cp?CoIII Catalyzed C-H Bond Activation for the Synthesis of Isoquinolin-3-ones
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A facile route toward the synthesis of isoquinolin-3-ones through a cooperative B(C6F5)3- and Cp?CoIII-catalyzed C-H bond activation of imines with diazo compounds is presented. The inclusion of a catalytic amount of B(C6F5)3 results in a highly efficient reaction, thus enabling unstable NH imines to serve as substrates. CoIII-operative catalysis: The first facile route toward the synthesis of isoquinolin-3-ones through cooperative C-H bond activation with B(C6F5)3 (BCF in picture) and Cp?CoIII (Cp?=C5Me5) is presented. The newly developed catalytic system is highly reactive, thus unstable NH imines can serve as substrates.
- Kim, Ju Hyun,Gre?ies, Steffen,Glorius, Frank
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supporting information
p. 5577 - 5581
(2016/05/09)
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- Conformationally locked chromophores of CFP and Sirius protein
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Recent works have demonstrated the potential of fluorescent protein chromophores as useful dyes with unique photophysical properties. Herein, we report the synthesis of two novel highly fluorescent dyes based on conformationally locked chromophores of the fluorescent proteins CFP and Sirius. These novel synthetic dyes demonstrate high fluorescence quantum yields and pH-independence in the physiological pH range, making them promising molecular tools for a broad range of fluorescent labeling applications.
- Baleeva, Nadezhda S.,Tsarkova, Aleksandra S.,Baranov, Mikhail S.
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supporting information
p. 3043 - 3045
(2016/07/06)
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- Transformation of RN=CHPh to R(R′3Si)NCH2Ph in the catalytic desulfurization of secondary thioamide with R′3SiH promoted by an iron complex
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The reaction of imine (RN=CHPh) with hydrosilane (R′3SiH) in the presence of CpFe(CO)2Me (1) revealed the formation of a hydrosilylation product (R(R′3Si)NCH2Ph). The findings helped us to understand the reaction mechanism of desulfurization of secondary thioamide catalyzed by 1 to give the corresponding imine and amine as a major and minor product, respectively.
- Fukumoto, Kozo,Sakai, Akane,Murai, Toshiaki,Nakazawa, Hiroshi
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p. 607 - 611
(2015/02/19)
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- Synthesis of α,β-unsaturated aldehydes based on a one-pot phase-switch dehydrogenative cross-coupling of primary alcohols
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An efficient one-pot ruthenium-catalyzed hydrogen-transfer strategy for a direct access to α,β-unsaturated aldehydes has been developed. The employment of enolates prepared in situ from alcohols avoided handling unstable aldehydes and provided a very appealing route to different cinnamaldehydes substituted in position 2. A silica-grafted amine was used as phase-switch tag leading to a selective one-pot process in favor of cross-dehydrogenative coupling products.
- Mura, Manuel G.,De Luca, Lidia,Taddei, Maurizio,Williams, Jonathan M. J.,Porcheddu, Andrea
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supporting information
p. 2586 - 2589
(2014/06/09)
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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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- Cobalt-catalyzed cyclization of carbon monoxide, imine, and epoxide
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Cobalt-catalyzed cyclization of CO, imine, and epoxide has been developed. A convenient catalyst system composed of Co2(CO)8 and LiCl is identified, and the substrate scope has been explored. The reaction provides an efficient method for the synthesis of substituted 1,3-oxazinan-4-ones.
- Zhang, Yubo,Ji, Jiamin,Zhang, Xiuliang,Lin, Shaohui,Pan, Qinmin,Jia, Li
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supporting information
p. 2130 - 2133
(2014/05/06)
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- Toward lead-oriented synthesis: One-pot version of castagnoli condensation with nonactivated alicyclic anhydrides
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One-pot variation of Castagnoli condensation, that is, reaction of cyclic anhydrides, amines, and aldehydes, has been developed as a combinatorial approach to 1,2-disubstituted 5-oxopyrrolidine- and 6-oxopiperidine-3-carboxylic acids, as well as their benzo-analogues. Utility of the method to multigram preparation of building blocks and synthetic intermediates was also demonstrated. The final products are obtained in high yields and diastereoselectivity. The method fits well in the concept of lead-oriented synthesis; in particular, it can be used for the design of lead-like compound libraries, even if the strictest cut-offs are applied to the physicochemical properties of their members.
- Ryabukhin, Sergey V.,Panov, Dmitriy M.,Granat, Dmitry S.,Ostapchuk, Eugeniy N.,Kryvoruchko, Dmitriy V.,Grygorenko, Oleksandr O.
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p. 146 - 153
(2014/04/03)
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- Controlling the exothermicity of O-arylation by evaporative cooling during the process development of fluoxetine hydrochloride
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This study illustrates the optimization of the O-arylation step of fluoxetine hydrochloride (1) synthesis. In the entire process, this is the most critical step that dictates the yield and quality of the product. The highlight of the process is the concept of evaporative cooling that was employed in manipulating the above highly exothermic reaction by introducing toluene as the cosolvent. The evaporative cooling not only aided in getting an efficient procedure but also increased the yield of 1 and simplified the work-up procedure. This was a protective approach adopted for process safety, considering the worst-case scenario in the plant.
- Mohanty, Sandeep,Roy, Amrendra Kumar,Kiran, S. Phani,Rafael, G. Eduardo,Kumar, K. P. Vinay,Karmakar, A. Chandra
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p. 875 - 885
(2014/08/05)
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- Desulfurization and H-migration of secondary thioamides catalyzed by an iron complex to yield imines and their reaction mechanism
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Secondary thioamides were converted into imines as the major products using hydrosilane in the presence of an iron catalyst. An iron carbene complex with a silyl thiolato ligand was isolated as one of the intermediates of the catalytic cycle and was characterized by X-ray analysis.
- Fukumoto, Kozo,Sakai, Akane,Hayasaka, Kazumasa,Nakazawa, Hiroshi
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supporting information
p. 2889 - 2892
(2013/06/27)
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- Oxidant-free conversion of primary amines to nitriles
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An amide-derived NNN-Ru(II) hydride complex catalyzes oxidant-free, acceptorless, and chemoselective dehydrogenation of primary and secondary amines to the corresponding nitriles and imines with liberation of dihydrogen. The catalyst system tolerates oxidizable functionality and is selective for the dehydrogenation of primary amines (-CH2NH2) in the presence of amines without α-CH hydrogens.
- Tseng, Kuei-Nin T.,Rizzi, Andrew M.,Szymczak, Nathaniel K.
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supporting information
p. 16352 - 16355
(2013/12/04)
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- One-step selective aerobic oxidation of amines to imines by gold nanoparticle-loaded rutile titanium(IV) oxide plasmon photocatalyst
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Among various metal oxide-supported Au nanoparticles, Au/rutile TiO 2 exhibits a particularly high level of visible-light activity for aerobic oxidation of amines to yield the corresponding imines on a synthetic scale with high selectivity (>99%) at 298 K. Experimental results have suggested that the reaction proceeds via the localized surface plasmon resonance-excited electron transfer from the Au nanoparticle to the TiO 2.
- Naya, Shin-Ichi,Kimura, Keisuke,Tada, Hiroaki
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- Simple and efficient one-pot solvent-free synthesis of N-methyl imines of aromatic aldehydes
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A one-pot solvent-free synthesis of N-methyl imines in good to excellent yields was performed by grinding together aromatic aldehydes and methylamine hydrochloride in the presence of a base. The best yields were achieved when an excess of methylamine hydrochloride and inexpensive sodium hydrogen carbonate was used (usually in a molar ratio ArCHO/CH3NH2· HCl/NaHCO3 = 1:5:5), allowing the reaction to proceed for 1 h (in the case of aromatic aldehydes containing electron-withdrawing substituents) or overnight (in the case of electron-rich aldehydes). After a simple work-up (extraction with diethyl ether) the obtained products were mostly pure enough for spectral characterization. In this way, 31 N-methyl imines were prepared, among which eight were synthesized for the first time. Their structures were elucidated by spectral means (1H- and 13C-NMR, IR, MS) whenever it was possible. In the case of salicylaldehyde and 4-chlorobenzaldehyde, the synthesis of the corresponding imines was also conducted on a gram-scale with a 72% and 84% isolated yield, respectively. The present approach not only provides good to high yields, but also eliminates the disadvantages of the traditional synthesis of N-methyl imines, such as the use of hazardous solvents and more or less expensive catalysts and the necessity of work/handling with an anhydrous gas in pressurized containers.
- Radulovi?, Niko S.,Miltojevi?, Ana B.,Vuki?evi?, Rastko D.
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p. 257 - 270
(2013/05/09)
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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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- 4-Phenyl tetrahydroisoquinolines as dual norepinephrine and dopamine reuptake inhibitors
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Novel 4-phenyl tetrahydroisoquinolines that inhibit both dopamine and norepinephrine transporters were designed and prepared. In this Letter, we describe the synthesis, in vitro activity and associated structure-activity relationships of this series. We also report the ex vivo NET occupancy of a representative compound, 41.
- Pechulis, Anthony D.,Beck, James P.,Curry, Matt A.,Wolf, Mark A.,Harms, Arthur E.,Xi, Ning,Opalka, Chet,Sweet, Mark P.,Yang, Zhicai,Vellekoop, A. Samuel,Klos, Andrew M.,Crocker, Peter J.,Hassler, Carla,Laws, Mia,Kitchen, Douglas B.,Smith, Mark A.,Olson, Richard E.,Liu, Shuang,Molino, Bruce F.
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p. 7219 - 7222
(2013/01/15)
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- Highly enantioselective synthesis of tetrahydroquinolines via cobalt(II)-catalyzed tandem 1,5-hydride transfer/cyclization
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A chiral catalyst prepared from N,N′-dioxide and Co(BF 4)2·6H2O was applied in the asymmetric hydride transfer initiated cyclization reaction, giving optically active tetrahydroquinolines in good yields with high enantioselectivities under mild reaction conditions. Meanwhile, in light of the absolute configuration of the product, a possible working model was proposed to explain the origin of the activation and asymmetric induction.
- Cao, Weidi,Liu, Xiaohua,Wang, Wentao,Lin, Lili,Feng, Xiaoming
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supporting information; scheme or table
p. 600 - 603
(2011/04/15)
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- Steric and electronic effects in capsule-confined green fluorescent protein chromophores
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The turn-on of emission in fluorescent protein chromophores sequestered in an "octaacid" capsule is controlled by stereoelectronic effects described by a linear free energy relationship. The stereochemical effects are governed by both the positions and volumes of the aryl substituents, while the electronic effects, including ortho effects, can be treated with Hammett σ parameters. The use of substituent volumes rather than A values reflects packing of the molecule within the confines of the capsule.
- Baldridge, Anthony,Samanta, Shampa R.,Jayaraj, Nithyanandhan,Ramamurthy,Tolbert, Laren M.
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supporting information; scheme or table
p. 712 - 715
(2011/04/15)
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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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- Catalytic intermolecular hetero-dehydro-diels-alder cycloadditions: Regioand diasteroselective synthesis of 5,6-dihydropyridin-2-ones
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A novel catalyzed intermolecular heterodehydro-Diels-Alder reaction between push-pull 1,3-dien-5-ynes and aldimines or silylaldimines is reported. The sequence is promoted both by gold(I) or silver(I) catalysts and leads to the diastereo- and regioselective formation of 5,6- dihydropyridin-2-ones.
- Fernandez-Garcia, Jesus Manuel,Fernandez-Rodriguez, Manuel A.,Aguilar, Enrique
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supporting information; experimental part
p. 5172 - 5175
(2011/12/04)
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- Efficient synthesis of new 4-arylideneimidazolin-5-ones related to the GFP chromophore by 2+3 cyclocondensation of arylideneimines with imidate ylides
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A 2+3 condensation of a wide assortment of Schiff bases, prepared from aromatic aldehydes and primary amines, with methyl (1-ethoxyethylideneamino) acetate allows convenient access to an extensive family of substituted 4-arylideneimidazolin-5-one analogues of the green fluorescent protein (GFP) chromophore. Georg Thieme Verlag Stuttgart · New York.
- Baldridge, Anthony,Kowalik, Janusz,Tolbert, Laren M.
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scheme or table
p. 2424 - 2436
(2010/09/06)
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- Activation of fluorescent protein chromophores by encapsulation
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(Figure Presented) Chromophores related to fluorescent proteins, when sequestered into the "octaacid" capsule, recover their fluorescence. The fluorescence recovery is related to the inhibition of torsional motions within the cavity, implicating the single-bond torsion as an important contributor to internal conversion within this important class of chromophores.
- Baldridge, Anthony,Samanta, Shampa R.,Jayaraj, Nithyanandhan,Ramamurthy,Tolbert, Laren M.
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supporting information; experimental part
p. 1498 - 1499
(2010/04/03)
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- A novel construction of 2-benzazepine scaffold based on TiCl 4-mediated tandem Mannich reaction - Aromatic electrophilic substitution
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A novel construction of 2-benzazepine derivatives based on TiCl 4-mediated tandem Mannich reaction of electron-rich benzyl iminium ions with alkenyl ethers and Friedel - Crafts-type alkylation is described. The protocol is amenable to provide the tricyclic furo[3,2-d][2]benzazepine and pyrano[3,2-d][2]benzazepine derivatives, respectively, with 2,3-dihydrofuran or 3,4-dihydro-2H-pyran as the substrates.
- Li, Liangxi,Li, Zhiming,Wang, Quanrui
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experimental part
p. 2754 - 2761
(2010/04/02)
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- Isomerization in fluorescent protein chromophores involves addition/elimination
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The green fluorescent protein (GFP) chromophore undergoes both photochemical and thermal isomerizations. Typically, the Z form is more stable and undergoes photochemical conversion to the E form followed by thermal reversion over a period of seconds or minutes. Although the mechanism of the thermal reversion has been the subject of some investigations, the surprisingly low activation energy for this process has not sparked any controversy. We now show that the chromophore is surprisingly stable in both E and Z forms and that the facile thermal reversion is the result of a novel nucleophilic addition/elimination mechanism. This observation may have implications for the intervention of such processes, as well as blinking and kindling, in fluorescent proteins. Copyright
- Dong, Jian,Abulwerdi, Fardokht,Baldridge, Anthony,Kowalik, Janusz,Solntsev, Kyril M.,Tolbert, Laren M.
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supporting information; experimental part
p. 14096 - 14098
(2009/03/11)
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- Synthesis of 2-alkyl-1-aryl-1,2-dihydrochromeno[2,3-c]pyrrole-3,9-dione derivatives
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A preparative procedure for the synthesis of 2-alkyl-1-aryl-1,2- dihydrochromeno[2,3-c]pyrrole-3,9-diones from methyl 4-(o-hydroxyphenyl)-2,4- dioxobutanoate, aromatic aldehyde, and aliphatic amine is described.
- Vydzhak,Panchishin, S. Ya.
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experimental part
p. 2391 - 2397
(2009/05/30)
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- Efficient microwave-assisted solvent-free synthesis of N-substituted aldimines
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Neat non-volatile amines react with various aromatic aldehydes in the absence of any catalyst, solid support, or solvent, to give imines after a reaction time of eight minutes under microwave irradiation by a clean and very efficient process (yields: 75-100%). In the case of volatile amine, methylamine, 1,3-dimethylurea dispersed on montmorillonite K10 is used as an amine precursor to prepare the corresponding imines. Georg Thieme Verlag Stuttgart.
- Paquin, Ludovic,Hamelin, Jack,Texier-Boullet, Francoise
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p. 1652 - 1656
(2007/10/03)
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- Diastereodirected alkylation of ketones and 1,3-diketones with N-[1H-Indol-3-yl(phenyl)methyl]-N-methylamine by the Michael reaction
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A method has been developed for introducing the 1H-indol-3-yl(phenyl)methyl residue into position 2 of ketones and 1,3-diketones. The principle of bringing in controlled diastereoselectivity based on the configuration of intermediates is demonstrated. 2005 Springer Science+Business Media, Inc.
- Semenov,Smushkevich,Levina,Kurkovskaya,Lysenko,Kachala
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p. 730 - 738
(2007/10/03)
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