- Organic reactions catalyzed by methylrhenium trioxide: Reactions of ethyl diazoacetate and organic azides
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Methylrhenium trioxide (CH3ReO3 or MTO) catalyzes several classes of reactions of ethyl diazoacetate, EDA. It is the first high valent oxo complex for carbene transfer. Under mild conditions and in the absence of other substrates, EDA was converted to a 9:1 mixture of diethyl maleate and diethyl fumarate. In the presence of alcohols, α-alkoxy ethyl acetates were obtained in good yield. The yields dropped for the larger and more branched alcohols, the balance of material being diethyl maleate and fumarate. An electron-donating group in the para position of phenols favors the formation of α-phenoxy ethyl acetates. The use of EDA to form α-thio ethyl acetates and N-substituted glycine ethyl esters, on the other hand, is hardly affected by the size or structure of the parent thiol or amine, with all of these reactions proceeding in high yield. MTO-catalyzed cycloaddition reactions occur between EDA and aromatic imines, olefins, and carbonyl compounds. Three-membered ring products are formed: aziridines, cyclopropanes, and epoxides, respectively. The reactions favor the formation of trans products, and provide a convenient route for the preparation of aziridines. Intermediate carbenoid and nitrenoid species have been proposed. In the presence of an oxygen source such as an epoxide, ethyl diazoacetate and azibenzil are converted to an oxalic acid monoethyl ester and tobenzil; at the same time the epoxide was converted to an olefin. These results provide further support for the proposed intermediate, a cyclic species containing Re, O, and CHCO2Et (or, occasionally, CPhC(O)Ph)in a three-membered ring.
- Zhu, Zuolin,Espenson, James H.
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- An in-depth analysis of the effect of substituents on imines in cycloaddition reactions with nitrosoalkenes
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An in-depth experimental and theoretical analysis of the reactions of simple acyclic imines with nitrosoalkenes is reported. The effect of the substituents on nitrogen as well as carbon atom of imines on the cycloaddition pathways followed is systematically explored. The reactions of various functionalized imines with nitrosoalkenes leading to the formation of imidazoles and imidazole-N-oxides have also been explored. The plausible mechanisms leading to various heterocycles have been proposed.
- Marwaha, Alka,Singh, Parvesh,Mahajan, Mohinder P.
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- Crystal phase effect of iron oxides on the aerobic oxidative coupling of alcohols and amines under mild conditions: A combined experimental and theoretical study
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Selective catalytic oxidation using air as the terminal oxidant is an ecofriendly route for the synthesis of fine and commodity chemicals. However, the catalyst generally faces the challenges of the inertness of molecular oxygen, limited substrate scope, poor selectivity, and high cost. Moreover, the toxicity of the catalyst should also be considered when the products are used in pharmaceutical or biotechnological areas. Here, upon investigating the dependence of catalytic oxidation on the crystal phases of iron oxides, we find that naked γ-Fe2O3 particles exhibit excellent catalytic activity, selectivity, and stability in a series of imine synthetic reactions. The performance of γ-Fe2O3 particles is significantly better than that of α-Fe2O3 and Fe3O4 under mild reaction conditions, and the γ-Fe2O3 catalyst can be separated from the reaction mixture magnetically. Both experimental and theoretical calculation results show that γ-Fe2O3 possesses supercapability for oxygen activation. The inverse spinel structure of γ-Fe2O3 has abundant cation vacancies, which confers unique electronic properties on surface Fe species. These Fe species tend to transfer electrons to molecular oxygen to form O2? or O22? species. These oxygen species are favorable for the dehydrogenation of alcohols, which is responsible for the high activity of γ-Fe2O3 in this coupling reaction.
- Geng, Longlong,Jian, Wei,Jing, Pei,Zhang, Wenxiang,Yan,Bai, Fu-Quan,Liu, Gang
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- Synthesis of [LAl(μ-S)2AlL] (L?=?HC(CMeNAr)2, Ar?=?2,6-Et2C6H3) with the insertion of sulfur into the Al–H bonds of LAlH2 and its application in catalysis
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Two aluminum complexes [LAl(μ-S)2AlL] (1) and [LAl(SeH)2] (2) were synthesized in good yield by reacting one equivalent of LAlH2 (L?=?HC(CMeNAr)2, Ar?=?2,6-Et2C6H3) with one equivalent of S and with two equivalents of Se without any catalysts, respectively. Complexes 1 and 2 have been characterized by 1H and 13C NMR, elemental analyses, and single crystal X-ray structural analysis. Furthermore, the good catalytic activity of 1 as bimetallic Lewis acid catalyst for the addition reaction of TMSCN to aldehydes and aldimine condensation reactions, respectively, were investigated.
- Zhong, Mingdong,Liu, Ying,Liu, Xin,Ma, Xiaoli,Yang, Zhi
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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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- Synthesis of organoaluminum chalcogenides and their applications in Lewis acid catalysis
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Two chalcogenide bridged bi-aluminum compounds [LAl(NMe3)(μ-S)Al(NMe3)L] (1) and [LAl(NMe3)(μ-Se)Al(NMe3)L] (2) were synthesized by reacting LAlH(NMe3) (L = 4-methylbenzylidene-o-aminothiophenol) with
- Ding, Yi,Ma, Xiaoli,Liu, Yashuai,Liu, Wenqing,Ni, Congjian,Yan, Ben,Yan, Li,Yang, Zhi
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- Direct and mild palladium-catalyzed aerobic oxidative synthesis of imines from alcohols and amines under ambient conditions
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By ligand, TEMPO, and base screening, we developed a mild and green one-pot imine synthesis from alcohols and amines via a low-loading palladium-catalyzed tandem aerobic alcohol oxidation-dehydrative condensation reaction that can be readily carried out in open air at room temperature.
- Jiang, Lan,Jin, Luolu,Tian, Haiwen,Yuan, Xueqin,Yu, Xiaochun,Xu, Qing
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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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- KOH-mediated transition metal-free synthesis of imines from alcohols and amines
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The various imines were prepared from alcohols and amines in moderate to good yields under an air atmosphere promoted by KOH, eliminating the need for toxic transition metal catalysts. Due to its simplicity, this protocol will have wide application in synthesis.
- Xu, Jian,Zhuang, Rongqiang,Bao, Lingling,Tang, Guo,Zhao, Yufen
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- Reaction of Thioaldehydes with Amines
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The reaction of phosphonium ylides with elemental sulfur gave thioaldehydes, which changed to the corresponding thioamides in good yields when treated with amines.When thioaldehydes containing α-hydrogens were treated with secondary amines, the corresponding enamines or reduction products were obtained.
- Okuma, Kentaro,Komiya, Yasuo,Ohta, Hiroshi
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- Air-Stable Half-Sandwich Iridium Complexes as Aerobic Oxidation Catalysts for Imine Synthesis
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Several N,O-coordinate half-sandwich iridium complexes, 1-5, containing constrained bulky β-enaminoketonato ligands were prepared and clearly characterized. Single-crystal X-ray diffraction characterization of these complexes indicates that the iridium center adopts a distorted octahedral geometry. Complexes 1-5 showed good catalytic efficiency in the oxidative homocoupling of primary amines, dehydrogenation of secondary amines, and the oxidative cross-coupling of amines and alcohols, which furnished various types of imines in good yields and high selectivities using O2 as an oxidant under mild conditions. No distinctive substituent effects of the iridium catalysts were observed in these reactions. The diverse catalytic activity, broad substrate scope, mild reaction conditions, and high yields of the products made this catalytic system attractive in industrial processes.
- Deng, Wei,Fan, Xiao-Nan,Ou, Hui-Dan,Yao, Zi-Jian
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- Nitrogen-coordinated cobalt nanocrystals for oxidative dehydrogenation and hydrogenation of N-heterocycles
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To endow non-noble metals with the high catalytic activity that is typically exhibited by noble metals is the central yet challenging aim for substituting noble metals. In this regard, by exploiting the coordination effect of nitrogen, we prepared cobalt nanocrystals stabilized by nitrogen-doped graphitized carbon (Co NCs/N-C). The obtained Co NC/N-C catalyst showed extraordinary performances toward both oxidative dehydrogenation of N-heterocycles and its reverse hydrogenation process under extremely mild conditions. A nearly quantitative conversion could be achieved for oxidative dehydrogenation even at room temperature (25 °C), for which the coordination effect of nitrogen is responsible: the interaction of Co-N induces a partial positive charge on the Co surface, thereby promoting the reaction. In contrast, cobalt nanocrystals supported by pristine carbon (Co NCs/C) proved to be inactive for oxidative dehydrogenation, owing to the lack of nitrogen. Moreover, in Co NCs/N-C, the N-doped graphitized carbon formed a protective layer for Co NCs, which preserved the active valence of Co species and prevented the catalyst from leaching. It was found that the catalyst still retained its excellent catalytic activity after five regeneration cycles; in comparison, its cobaltous oxide counterpart (CoOx/N-C) was barely active. As for the mechanism, electron paramagnetic resonance (EPR) analysis revealed the formation of superoxide anion radicals during the dehydrogenation process. Interestingly, the pressure of feed hydrogen had little effect on the hydrogenation process. Our Co NC/N-C catalyst is capable of activating molecular oxygen and hydrogen as effectively as noble metals; the coordination effect of nitrogen and the protection by the carbon layer in combination confer tremendous potential on the Co NCs/N-C for substituting noble-metal-based catalysts and soluble catalysts for homogeneous reactions.
- Wu, Yue,Chen, Zheng,Cheong, Weng-Chon,Zhang, Chao,Zheng, Lirong,Yan, Wensheng,Yu, Rong,Chen, Chen,Li, Yadong
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- Ligand-Controlled Inversion of Diastereo- and Enantioselectivity in Silver-Catalyzed Azomethine Ylide-Imine Cycloaddition of Glycine Aldimino Esters with Imines
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A highly diastereo- and enantioselective silver-catalyzed azomethine ylide-imine (AYI) cycloaddition reaction of glycine aldimino esters with imines was developed in which the Xing-Phos-controlled syn-selective or DTBM-Segphos-induced anti-selective AYI cycloaddition reaction could be applied to the synthesis of a variety of stereodivergent 1-alkyl-2,5-substituted imidazolidines with high yields and excellent enantioselectivities (up to 99% ee) as well as good diastereoselectivities (up to 99:1 dr) under mild reaction conditions.
- Yu, Bo,Yang, Ke-Fang,Bai, Xing-Feng,Cao, Jian,Zheng, Zhan-Jiang,Cui, Yu-Ming,Xu, Zheng,Li, Li,Xu, Li-Wen
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- CeO2 nanorods anchored on mesoporous carbon as an efficient catalyst for imine synthesis
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CeO2 nanorods anchored on mesoporous carbon exhibit high activity and stability in aerobic oxidative coupling of alcohols and amines to imines. The abundant surface Ce3+ and the suitable interaction between CeO2 nanorods and the carbon support should be responsible for the excellent catalytic behaviors.
- Geng, Longlong,Song, Jinling,Zhou, Yahui,Xie, Yan,Huang, Jiahui,Zhang, Wenxiang,Peng, Luming,Liu, Gang
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- A mild and catalytic decarboxylation of α-iminoacids by tributyl phosphine
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α-Iminoacids, prepared from α-keto acids and primary amines, undergo decarboxylation to the corresponding imines by reaction with a catalytic amount of tributylphosphine. No reaction has been observed with α-keto acids or their phenyl-hydrazone, tosyl-hydrazone or oxime derivatives under the same conditions. However, carboxy-azines react rapidly with tributylphosphine and give the corresponding aldazines quantitatively. The mechanism of this reaction is also discussed.
- Barton, Derek H. R.,Taran, Frederic
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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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- Molybdenum Nitride Nanocatalyst Derived from Melamine and Polyoxometalate-based Hybrid for Oxidative Coupling of Amines to Imines with Air
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Molybdenum nitride (Mo2N) is one of the most promising alternative catalysts for a wide range of Pt-catalyzed catalytic applications but is seldom investigated in oxidative coupling of amines to imines. A Mo2N-based nanocatalyst is successfully achieved by the hybridization of PMo12O403? (PMo)-paired ionic pyridine-4-carboxylic acid (PC) and melamine (Mel), followed by calcination in N2. Melamine acts as an outstanding carburization and nitridation reagent that can convert into carbon nitride, and meanwhile the released N element react with Mo species in PMo to form Mo2N. The obtained catalyst PC-PMo-Mel-800 exhibits high activity and remarkable stability for the oxidative coupling of amines to imines under solvent-free and atmospheric conditions. This is the first case of Mo2N-catalyzed oxidative coupling reaction catalyst. The strategy reported herein for fabricating Mo2N may provide a significant and interesting approach to design more transition metal nitrides for wide catalytic applications.
- Li, Yue,Xiao, Kang,Li, Jingjing,Jiang, Pingping,Jiang, Yuchen,Du, Shengyu,Leng, Yan
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- New trans dichloro (triphenylphosphine)platinum(II) complexes containing N-(butyl),N-(arylmethyl)amino ligands: Synthesis, cytotoxicity and mechanism of action
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Some new platinum(II) complexes have been prepared, of general formula trans-[PtCl2(PPh3){NH(Bu)CH2Ar}], where the dimension of the Ar residue in the secondary amines has been varied from small phenyl to large pyrenyl group. The obtained complexes, tested in vitro towards a panel of human tumor cell lines showed an interesting antiproliferative effect on both cisplatin-sensitive and -resistant cells. For the most cytotoxic derivative 2a the investigation on the mechanism of action highlighted the ability to induce apoptosis on resistant cells and interestingly, to inhibit the catalytic activity of topoisomerase II.
- Dalla Via, Lisa,García-Argáez, Aída Nelly,Agostinelli, Enzo,Belli Dell'Amico, Daniela,Labella, Luca,Samaritani, Simona
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- Photolysis of 3-chloro-3-aryldiazirines in the presence of amines and allyl alcohol
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When photolysis of arylchlorodiazirines is performed in the presence of either alkyl- or allyl-substituted amines, either N-alkyl- or N-allyl-substituted amines result as the sole high-yield (64-93%) products. Photolysis in the presence of phenylally-lami
- Liu,Romashin,Venkatachalam
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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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supporting information
p. 1804 - 1808
(2021/03/08)
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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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- Synthesis of Lactams by Reductive Amination of Carbonyl Derivatives with ω-Amino Fatty Acids under Hydrosilylation Conditions
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An efficient method for the preparation of lactams from ω-amino fatty acids under hydrosilylation is described. A variety of lactams such as pyrrolidinones, piperidinones and 2-azepanones were selectively synthesised in moderate to excellent yields (29 examples, up to 95 % isolated yields) with a good functional group tolerance. Notably, no metallic based catalyst was required to perform this transformation.
- Tongdee, Satawat,Wei, Duo,Wu, Jiajun,Netkaew, Chakkrit,Darcel, Christophe
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p. 5536 - 5539
(2021/08/07)
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- Cyclometalated Half-Sandwich Iridium(III) Complexes: Synthesis, Structure, and Diverse Catalytic Activity in Imine Synthesis Using Air as the Oxidant
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Four air-stable cyclometalated half-sandwich iridium complexes 1-4 with C,N-donor Schiff base ligands were prepared through C-H activation in moderate-to-good yields. These complexes have been well characterized, and their exact structure was elaborated on by single-crystal X-ray analysis. The iridium(III) complexes 1-4 showed good catalytic activity in the imine synthesis under open-flask conditions (air as the oxidant) from primary amine oxidative homocoupling, secondary amine dehydrogenation, and the cross-coupling reaction of amine and alcohol. Substituents bonded on the ligands of the iridium complexes displayed little effect on the catalytic efficiency. The stability and good catalytic efficiency of the iridium catalysts, mild reaction conditions, and substrate universality showed their potential application in industrial production.
- Li, Rong-Jian,Ling, Chun,Lv, Wen-Rui,Deng, Wei,Yao, Zi-Jian
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p. 5153 - 5162
(2021/05/04)
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- Fe2Mn(μ3-O)(COO)6 Cluster Based Stable MOF for Oxidative Coupling of Amines via Heterometallic Synergy
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The direct catalytic oxidative coupling of amines is one of the attracting methods for the synthesis of a variety of pharmaceutical or industrial needed imines. Numerous earth-abundant manganese based salts, oxides, and complexes have been applied in this reaction. However, these compounds suffered from difficult separation, large catalyst loading, complicated reactivation or indeterminate activity. Considering the facts that metal-organic frameworks (MOFs) with crystalline structure, precise composition, and enormous surface area have superior performance in heterogeneous catalytic reactions, herein, we introduced Mn into [Fe3(μ3-O)(CH3COO)6], one of the precursors for the preparation of stable MOFs, and got [Fe2Mn(μ3-O)(CH3COO)6] cluster. After ligand replacement with biphenyl-3,4’,5-tricarboxylic acid (BPTC), heterometallic cluster-based [Fe2Mn(μ3-O)(BPTC)2(DMF)2(H2O)] (1) was obtained. As expected, 1 is stable and able to catalyze the homo- or cross-coupling of amines effectively and selectively with 0.9 mol% catalyst loading at room temperature. Control experiments indicated that the catalytic activity of 1 mainly stems from Mn sites and that Fe synergistically contributes to the stability. Additionally, 1 is recyclable and can be reused easily for at least 8 runs without obvious decrease in catalytic ability. To our knowledge, 1 should be the first heterometallic cluster-based MOF with defined structure suitable for the synthesis of diverse imines from oxidative coupling of amines under mild conditions, which may shed light on the easy preparation of effective heterogeneous catalysts for organic synthesis.
- Wang, Ying-Xia,Wang, Hui-Min,Meng, Pan,Song, Dong-Xia,Qi, Zhikai,Zhang, Xian-Ming
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supporting information
p. 2983 - 2989
(2021/08/30)
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- Redox-Neutral Imination of Alcohol with Azide: A Sustainable Alternative to the Staudinger/Aza-Wittig Reaction
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The traditional Staudinger/aza-Wittig reaction represents one of the most powerful tools for imine formation. However, for this multistep procedure, the sacrificial phosphine has to be used, resulting in difficulties in the purification process and waste disposal at the same time. Here, we report a redox-neutral azide-alcohol imination methodology enabled by a base-metal nickel PN3 pincer catalyst. The one-step, waste-free, and high atom-economical features highlight its advantages further. Moreover, mechanistic insight suggests a non-metal-ligand cooperation pathway based on the observation of an intermediate and density functional theory calculations.
- Li, Huaifeng,Lupp, Daniel,Das, Pradip K.,Yang, Li,Gon?alves, Théo P.,Huang, Mei-Hui,El Hajoui, Marwa,Liang, Lan-Chang,Huang, Kuo-Wei
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p. 4071 - 4076
(2021/04/12)
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- Highly economical and direct amination of sp3carbon using low-cost nickel pincer catalyst
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Developing more efficient routes to achieve C-N bond coupling is of great importance to industries ranging from products in pharmaceuticals and fertilizers to biomedical technologies and next-generation electroactive materials. Over the past decade, improvements in catalyst design have moved synthesis away from expensive metals to newer inexpensive C-N cross-coupling approaches via direct amine alkylation. For the first time, we report the use of an amide-based nickel pincer catalyst (1) for direct alkylation of amines via activation of sp3 C-H bonds. The reaction was accomplished using a 0.2 mol% catalyst and no additional activating agents other than the base. Upon optimization, it was determined that the ideal reaction conditions involved solvent dimethyl sulfoxide at 110 °C for 3 h. The catalyst demonstrated excellent reactivity in the formation of various imines, intramolecularly cyclized amines, and substituted amines with a turnover number (TON) as high as 183. Depending on the base used for the reaction and the starting amines, the catalyst demonstrated high selectivity towards the product formation. The exploration into the mechanism and kinetics of the reaction pathway suggested the C-H activation as the rate-limiting step, with the reaction second-order overall, holding first-order behavior towards the catalyst and toluene substrate.
- Brandt, Andrew,Rangumagar, Ambar B.,Szwedo, Peter,Wayland, Hunter A.,Parnell, Charlette M.,Munshi, Pradip,Ghosh, Anindya
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p. 1862 - 1874
(2021/01/20)
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- Catalyst- And Solvent-Free Synthesis of α-Amino Polyfluoroalkylphosphonates from Bis(fluoroalkyl) Phosphonates and Aldimines
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The catalyst- and solvent-free reaction between bis(fluoroalkyl) phosphonates and aldimines occurs under mild conditions (20-22 °C, 0.25-4 h) to afford a new family of α-amino polyfluoroalkylphosphonates in up to quantitative yields.
- Arbuzova, Svetlana N.,Gusarova, Nina K.,Kazantseva, Tatyana I.,Kolyvanov, Nikita A.,Trofimov, Boris A.,Verkhoturova, Svetlana I.,Zinchenko, Sergey V.
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p. 1531 - 1540
(2020/05/19)
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- Tunable Synthesis of α-Amino Boronic Esters from Available Aldehydes and Amines through Sequential One-Pot Dehydration and Copper-Catalyzed Borylacylation
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Copper-catalyzed multicomponent borylacylation of imines with acid chlorides and bis(pinacolato)diboron was developed for the preparation of synthetically useful and pharmacologically relevant α-amino boronic acid derivatives. Starting from a range of acid chlorides and imines with aryl, heteroaryl, and alkyl substituents, most of these ligand-free reactions proceeded smoothly at room temperature in moderate to good yields. Furthermore, a facile and convenient one-pot, multistep access to the direct synthesis of α-amino boronic acid derivatives from available aldehydes and amines was also developed.
- Xia, Qi,Chang, Hua-Rong,Li, Juan,Wang, Jia-Yi,Peng, Yan-Qing,Song, Gong-Hua
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p. 2716 - 2724
(2020/01/31)
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- Diethylsilane as a Powerful Reagent in Au Nanoparticle-Catalyzed Reductive Transformations
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Diethylsilane (Et2SiH2), a simple and readily available dihydrosilane, that exhibits superior reactivity, as compared to monohydrosilanes, in a series of reductive transformations catalyzed by recyclable and reusable Au nanoparticles (1 mol-%) supported on TiO2. It reduces aldehydes or ketones almost instantaneously at ambient conditions. It can be used in a one pot rapid reductive amination procedure, in which premixing of aldehyde and amine is required prior to the addition of the reducing agent and the catalyst, even in a protic solvent. An unprecedented method for the synthesis of N-arylisoindolines is also shown in the reductive amination between o-phthalaldehyde and anilines. In this transformation, it is proposed that the intermediate N,2-diphenylisoindolin-1-imines are reduced stepwise to the isoindolines. Finally, Et2SiH2 readily reduces amides into amines in excellent yields and shorter reaction times relative to previously known analogous nano Au(0)-catalyzed protocols.
- Louka, Anastasia,Kidonakis, Marios,Saridakis, Iakovos,Zantioti-Chatzouda, Elisavet-Maria,Stratakis, Manolis
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p. 3508 - 3514
(2020/06/02)
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- Kinetic and thermodynamic modulation of dynamic imine libraries driven by the hexameric resorcinarene capsule
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The composition of dynamic covalent imine libraries (DCL) adapts to the presence of the hexameric resorcinarene capsule. In the presence of the self-assembled capsule, a kinetic and thermodynamic modulation of the imine constituents of the DCLs was observed, which was induced by an unusual predatory action of the capsule on specific imine constituents. More complex 2 × 2 DCLs also adapt to the presence of the hexameric capsule, showing a thermodynamic and kinetic modulation of the constituents induced by the predatory action of the capsule. By cross-referencing experimental data, a good selectivity (up to 66%) for one constituent can be induced in a 2 × 2 DCL.
- Gambaro, Stefania,Talotta, Carmen,Della Sala, Paolo,Soriente, Annunziata,De Rosa, Margherita,Gaeta, Carmine,Neri, Placido
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supporting information
p. 14914 - 14923
(2020/10/13)
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- Bidentate geometry-constrained iminopyridyl nickel-catalyzed synthesis of amines or imines via borrowing hydrogen or dehydrogenative condensation
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The efficient Ni-catalyzed N-alkylation of various anilines with alcohols via borrowing hydrogen is reported using a bidentate geometry-constrained iminopyridyl nickel complex as the catalyst. Substituted benzylic alcohols and short/long chain aliphatic alcohols could be applied as the alkylation sources to couple with aromatic and heteroaromatic amines to give a diverse set of N-alkylation outcomes in moderate to excellent yields. The nickel catalytic system was also suitable for aliphatic amines, selectively delivering the corresponding imines via an acceptorless dehydrogenative condensation strategy.
- Jiang, Yong,Hu, Miao,Sun, Nan,Hu, Baoxiang,Shen, Zhenlu,Hu, Xinquan,Jin, Liqun
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supporting information
(2020/11/27)
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- Polyoxometalate catalyzed imine synthesis: Investigation of mechanistic pathways
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The syntheses of imines by oxidative coupling of primary alcohols and amines were achieved by using 2 molpercent polyoxometalate (POM) Na12[WZn3(H2O)2(ZnW9O34)2] (Zn–WZn3) catalyst in the presence of t-BuOK and di-oxygen with excellent conversion (up to 100percent) and selectivity (up to 100percent). Non-noble metal-based POM catalyst in the presence of base represents a new reaction protocol for the selective synthesis of imine from both aromatic and aliphatic primary amines with functional group tolerance. Control experiment shows the formation of di-oxygen bind Zn–WZn3 activated species. The electron-density of POM is mostly situated on the surface oxygen atoms of W–O–W bonds which can engage the alcoholic OH group and helps for the imine selectivity in the second step of imine synthesis.
- Adhikary, Subhasis D.,Mandal, Debaprasad
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supporting information
(2020/05/25)
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- Uniform Cu/chitosan beads as a green and reusable catalyst for facile synthesis of iminesviaoxidative coupling reaction
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A nonprecious metal and biopolymer-based catalyst, Cu/chitosan beads, has been successfully prepared by using a software-controlled flow system. Uniform, spherical Cu/chitosan beads can be obtained with diameters in millimeter-scale and narrow size distribution (0.78 ± 0.04 mm). The size and morphology of the Cu/chitosan beads are reproducible due to high precision of the flow rate. In addition, the application of the Cu/chitosan beads as a green and reusable catalyst has been demonstrated using a convenient and efficient protocol for the direct synthesis of iminesviathe oxidative self- and cross-coupling of amines (24 examples) with moderate to excellent yields. Importantly, the beads are stable and could be reused more than ten times without loss of the catalytic performance. Furthermore, because of the bead morphology, the Cu/chitosan catalyst has greatly simplified recycling and workup procedures.
- Bunchuay, Thanthapatra,Chantiwas, Rattikan,Chutimasakul, Threeraphat,Intanin, Apichai,Na Nakhonpanom, Pakamon,Tantirungrotechai, Jonggol,Tirdtrakool, Warinda
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p. 21009 - 21018
(2020/06/22)
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- Au nanoparticle-immobilized L-cysteine-paired porous ionic copolymer as an efficient catalyst for additive-free oxidative coupling of alcohols and amines
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Herein, an L-cysteine-paired ionic copolymer (DVB-[MimLcy]n) with mesoporosity was prepared by free radical copolymerization of divinylbenzene (DVB) and imidazolium ionic liquids (ILs), followed by anion-exchange with L-cysteine. Because of the rich functional groups of –NH2, –SH, and –COO– and the porous framework, the DVB-[MimLcy]3 was revealed to be an ideal stabilizer for metal nanoparticles (NPs). Highly uniform dispersed small Au NPs (2–3 nm) immobilized on DVB-[MimLcy]3 (Aua/DVB-[MimLcy]3) can act as an efficient heterogeneous catalyst for additive-free synthesis of imines through coupling of a broad range of alcohols and organic amines and can be easily recovered and steadily reused several times.
- Du, Shengyu,Zhang, Chenjun,Jiang, Yuchen,Jiang, Pingping,Leng, Yan
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- Colloidal and Nanosized Catalysts in Organic Synthesis: XXIII. Reductive Amination of Carbonyl Compounds Catalyzed by Nickel Nanoparticles in a Plug-Flow Reactor
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Reductive amination of aldehydes and ketones with primary and secondary amines under catalysis with nickel nanoparticles supported on zeolite X, MgO, or activated carbon in the gas phase or in the gas-liquid system in a plug-flow reactor proceeds at atmospheric pressure of hydrogen with the formation of secondary or tertiary amines in high yield.
- Mokhov, V. M.,Nebykov, D. N.,Paputina, A. N.,Popov, Yu. V.,Shishkin, E. V.
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p. 2333 - 2340
(2020/02/25)
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- Synthesis of Secondary Aldimines from the Hydrogenative Cross-Coupling of Nitriles and Amines over Al2O3-Supported Ni Catalysts
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A heterogeneous Ni catalyst was discovered to be active in the synthesis of secondary cross-imines via hydrogenative coupling of nitriles and amines. The mesoporous Al2O3-supported Ni nanoparticles (abbreviated as Ni/m-Al2O3-600, where 600 represents the reduction temperature) were active in hydrogenative coupling of nitriles and amines reaction at 80 °C and 1 bar H2, affording corresponding cross-imines with yields in the range 64.1-98.1%. Density functional theory calculations reveal the hydrogenation of benzonitrile (PhCN) to benzylamine (PhCH2NH2) has higher activation energy than that for hydrogenative cross-coupling of PhCN and RNH2 on the Ni/m-Al2O3-600 catalyst, suggesting the latter reaction is more favorable. The theoretical calculations are in good agreement with our experimental results.
- Zhou, Peng,Jiang, Liang,Wang, Shuguo,Hu, Xun,Wang, Hongming,Yuan, Ziliang,Zhang, Zehui
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p. 8413 - 8423
(2019/09/07)
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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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- Mesoporous cobalt/manganese oxide: A highly selective bifunctional catalyst for amine-imine transformations
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Herein, we discuss a heterogeneous catalytic protocol using cobalt doped mesoporous manganese oxide for amine-alcohol cross-coupling to selectively produce symmetric or asymmetric imines. Thorough investigations on the surface chemistry and physical properties of the material revealed its outstanding oxidation-reduction properties and reaction mechanism which was supported by quantum mechanical calculations done by using density functional theory (DFT).
- Dutta, Biswanath,March, Seth,Achola, Laura,Sahoo, Sanjubala,He, Junkai,Shirazi Amin, Alireza,Wu, Yang,Poges, Shannon,Pamir Alpay,Suib, Steven L.
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p. 3180 - 3185
(2018/07/29)
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- Direct synthesis of imines by 9-azabicyclo-[3,3,1]nonan-N-oxyl/KOH-catalyzed aerobic oxidative coupling of alcohols and amines
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A simple and efficient method for preparation of imines by the oxidative coupling of benzyl alcohols with aromatic amines or aliphatic amines was developed. The reaction was catalyzed by 9-azabicyclo[3.3.1]nonan-N-oxyl (ABNO)/KOH with air as the economic and green oxidant. Under the optimal reaction conditions, a variety of imines were obtained in 80%-96% isolated yields.
- Wan, Yan,Ma, Jia-Qi,Hong, Chao,Li, Mei-Chao,Jin, Li-Qun,Hu, Xin-Quan,Hu, Bao-Xiang,Mo, Wei-Min,Sun, Nan,Shen, Zhen-Lu
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p. 1269 - 1272
(2017/10/26)
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- Efficient Rare-Earth-Based Coordination Polymers as Green Photocatalysts for the Synthesis of Imines at Room Temperature
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Five new rare-earth coordination polymers (CPs) were designed in order to offer a remarkable platform that contains light-harvesting antennas and catalytic active centers to achieve solar-energy conversion as green alternatives in the synthesis of imines. These five new spirobifluorene-containing Ln-CPs, named [Er3(Hsfdc)3(sfdc)3(H2O)]·xH2O (RPF-30-Er), [Ln(Hsfdc)(sfdc)(EtOH)]·S (RPF-31-Ln, where Ln = La, Nd, and Sm and S = H2O or EtOH), and [Ho(Hsfdc)(sfdc)(H2O)] (RPF-32-Ho) (RPF = rare-earth polymeric framework and H2sfdc = 9,9′-spirobi[9H-fluorene]-2,2′-dicarboxylic acid), have been solvothermally synthesized, and their structural features can be described as follows: (i) RPF-30-Er shows a 3D framework in which the inorganic trimers (secondary building units) are cross-linked by Hsfdc- and sfdc2- linkers displaying a pcu topology. (ii) The isostructural RPF-31-Ln series of materials, together with RPF-32-Ho, exhibit a 1D network of chains growing along the a axis with a ribbon-of-rings topology type. The photocatalytic activity of the RPF-n materials was tested in the oxidative coupling of amines using molecular oxygen and air as oxidizing agents under warm light. Among the materials investigated, RPF-31-Nd was chosen to further investigate the approach in the selectivity of different amine derivates.
- Aguirre-Díaz, Lina M.,Snejko, Natalia,Iglesias, Marta,Sánchez, Félix,Gutiérrez-Puebla, Enrique,Monge, M. ángeles
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p. 6883 - 6892
(2018/06/26)
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- PdAu@MIL-100(Fe) cooperatively catalyze tandem reactions between amines and alcohols for efficient N-alkyl amines syntheses under visible light
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PdAu@MIL-100(Fe), with PdAu alloy nanoparticles of ca. 1.7 nm encapsulated inside MIL-100(Fe) cavities, were prepared via a double-solvent impregnation followed by photoreduction. As compared with bare Pd@MIL-100(Fe), bimetallic PdAu@MIL-100(Fe) showed superior activities for the tandem reactions between amines and alcohols to produce N-alkyl amines under visible-light irradiation, ascribed to the promoting effect of metallic Au in the photocatalytic alcohol-to-aldehyde dehydrogenation. A Pd/Au ratio dependent N-alkylation activity was observed over PdAu@MIL-100(Fe), implying the possibility of synchronizing the reaction rates of two consecutive steps in the N-alkylation reaction, i.e., photocatalytic alcohol-to-aldehyde dehydrogenation and imines hydrogenation, to optimize the whole reaction. This study provides a highly efficient and stable catalytic system for the realization of alkylation of amines via a successful coupling of MOF-based photocatalysis and metal nanoparticle-based hydrogenation. This work also demonstrates that the reaction rates of different catalytic steps in a cascade/tandem reaction can be synchronized for an efficient overall reaction via a rational design of the multifunctional catalysts.
- Wang, Dengke,Pan, Yating,Xu, Lizhi,Li, Zhaohui
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p. 248 - 254
(2018/04/02)
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- Mechanistic Studies on the Michael Addition of Amines and Hydrazines to Nitrostyrenes: Nitroalkane Elimination via a Retro-aza-Henry-Type Process
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In this article we report on the mechanistic studies of the Michael addition of amines and hydrazines to nitrostyrenes. Under the present conditions, the corresponding N-alkyl/aryl substituted benzyl imines and N-methyl/phenyl substituted benzyl hydrazones were observed via a retro-aza-Henry-type process. By combining organic synthesis and characterization experiments with computational chemistry calculations, we reveal that this reaction proceeds via a protic solvent-mediated mechanism. Experiments in deuterated methanol CD3OD reveal the synthesis and isolation of the corresponding deuterated intermediated Michael adduct, results that support the proposed slovent-mediated pathway. From the synthetic point of view, the reaction occurs under mild, noncatalytic conditions and can be used as a useful platform to yield the biologically important N-methyl pyrazoles in a one-pot manner, simple starting with the corresponding nitrostyrenes and the methylhydrazine.
- Kallitsakis, Michael G.,Tancini, Peter D.,Dixit, Mudit,Mpourmpakis, Giannis,Lykakis, Ioannis N.
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p. 1176 - 1184
(2018/02/09)
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- Grouping Effect of Single Nickel?N4 Sites in Nitrogen-Doped Carbon Boosts Hydrogen Transfer Coupling of Alcohols and Amines
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As a new type of heterogeneous catalyst with “homogeneous-like” activity, single-site transition-metal materials are usually treated as integrated but separate active centers. A novel grouping effect is reported for single Ni?N4 sites in nitrogen-doped carbon (Ni/NC), where an effective ligand-stabilized polycondensation method endows Ni/NC nanocatalysts with a high content of single-site Ni up to 9.5 wt %. The enhanced electron density at each single Ni?N4 site promotes a highly efficient hydrogen transfer, which is exemplified by the coupling of benzyl alcohol and aniline into N-benzylaniline with a turnover frequency (TOF) value of 7.0 molN-benzylaniline molmetal?1 h?1; this TOF outpaces that of reported stable non-noble-metal-based catalysts by a factor of 2.
- Su, Hui,Gao, Peng,Wang, Meng-Ying,Zhai, Guang-Yao,Zhang, Jun-Jun,Zhao, Tian-Jian,Su, Juan,Antonietti, Markus,Li, Xin-Hao,Chen, Jie-Sheng
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supporting information
p. 15194 - 15198
(2018/10/31)
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- The synthesis of α-aryl-α-aminophosphonates and α-aryl-α-aminophosphine oxides by the microwave-assisted Pudovik reaction
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A family of α-aryl-α-aminophosphonates and α-aryl-α-aminophosphine oxides was synthesized by the microwave-assisted solvent-free addition of dialkyl phosphites and diphenylphosphine oxide, respectively, to imines formed from benzaldehyde derivatives and primary amines. After optimization, the reactivity was mapped, and the fine mechanism was evaluated by DFT calculations. Two α-aminophosphonates were subjected to an X-ray study revealing a racemic dimer formation made through a N-H?O=P intermolecular hydrogen bridges pair.
- Bálint, Erika,Tajti, ádám,ádám, Anna,Csontos, István,Karaghiosoff, Konstantin,Czugler, Mátyás,ábrányi-Balogh, Péter,Keglevich, Gy?rgy
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supporting information
p. 76 - 86
(2017/02/15)
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- Method for preparing imine compound from alcohol and amine through catalytic oxidation
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The invention discloses a method for preparing an imine compound from alcohol and amine through catalytic oxidation. According to the method, an alcohol compound and an amine compound are used as reaction substrates, and a feeding mol ratio of the alcohol compound to the amine compound is 100: 100-60; 9-azabicyclo[3.3.1]nonane N-oxyl free radical is used as a catalyst, potassium hydroxide is used as an auxiliary agent, and a feeding mol ratio of the amine compound to the 9-azabicyclo[3.3.1]nonane N-oxyl free radical to potassium hydroxide is 100: 1-6: 10-50; air is used as an oxidizing agent, the reaction substrates are added into an organic solvent, and the mass of the used organic solvent is 2.5 to 5 times of the reaction substrate the amine compound; and a reaction is carried out at normal pressure at a temperature of 70 to 110 DEG C for 2 to 12 h, and aftertreatment is carried out after completion of the reaction so as to obtain the imine compound. The method provided by the invention is simple and safe to operate, reduces environmental cost due to usage of clean oxygen as the oxidizing agent and prevents the problem of transition-metal pollution by discarding usage of any transition-metal catalyst.
- -
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Paragraph 0054
(2017/08/31)
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- Activated Carbon Supported Ruthenium Nanoparticles Catalyzed Synthesis of Imines from Aerobic Oxidation of Alcohols with Amines
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Abstract: Imines were synthesized from the cross-coupling of alcohols with amines catalyzed by activated carbon (AC) supported ruthenium nanoparticles under atmospheric molecular oxygen without aid of any additives. The readily prepared catalyst 5%Ru/AC showed good to excellent (yield > 90%) performances in the reaction of aromatic and heterocyclic alcohols with various amines, such as aromatic, aliphatic and heterocyclic amines. This protocol is simple, efficient, and environmentally friendly, and the catalyst can be easily recovered without major ruthenium loss. Graphical Abstract: Imines were synthesized from the cross-coupling of alcohols with amines catalyzed by activated carbon (AC) supported ruthenium nanoparticles under atmospheric molecular oxygen without aid of any additives. This protocol is simple, efficient, and environment friendly, and the readily prepared catalyst 5%Ru/AC showed good to excellent performances in the reaction of aromatic and heterocyclic alcohols with various amines, such as aromatic, and aliphatic amines. [Figure not available: see fulltext.]
- Zhang, Yuecheng,Lu, Fei,Zhang, Hong-Yu,Zhao, Jiquan
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- Transition-Metal-Controlled Inorganic Ligand-Supported Non-Precious Metal Catalysts for the Aerobic Oxidation of Amines to Imines
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Most state-of-art transition-metal catalysts usually require organic ligands, which are essential for controlling the reactivity and selectivity of reactions catalyzed by transition metals. However, organic ligands often suffer from severe problems including cost, toxicity, air/moisture sensitivity, and being commercially unavailable. Herein, we show a simple, mild, and efficient aerobic oxidation procedure of amines using inorganic ligand-supported non-precious metal catalysts 1, (NH4)n[MMo6O18(OH)6] (M=Cu2+; Fe3+; Co3+; Ni2+; Zn2+, n=3 or 4), synthesized by a simple one-step method in water at 100 °C, demonstrating that the catalytic activity and selectivity can be significantly improved by changing the central metal atom. In the presence of these catalysts, the catalytic oxidation of primary and secondary amines, as well as the coupling of alcohols and amines, can smoothly proceed to afford various imines with O2 (1 atm) as the sole oxidant. In particular, the catalysts 1 have transition-metal ion core, and the planar arrangement of the six MoVI centers at their highest oxidation states around the central heterometal can greatly enhance the Lewis acidity of catalytically active sites, and also enable the electrons in the center to delocalize onto the six edge-sharing MO6 units, in the same way as ligands in traditional organometallic complexes. The versatility of this methodology maybe opens a path to catalytic oxidation through inorganic ligand-coordinated metal catalysis.
- Yu, Han,Zhai, Yongyan,Dai, Guoyong,Ru, Shi,Han, Sheng,Wei, Yongge
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supporting information
p. 13883 - 13887
(2017/10/13)
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- Practical Synthesis of Amides via Copper/ABNO-Catalyzed Aerobic Oxidative Coupling of Alcohols and Amines
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A modular Cu/ABNO catalyst system has been identified that enables efficient aerobic oxidative coupling of alcohols and amines to amides. All four permutations of benzylic/aliphatic alcohols and primary/secondary amines are viable in this reaction, enabling broad access to secondary and tertiary amides. The reactions exhibit excellent functional group compatibility and are complete within 30 min-3 h at rt. All components of the catalyst system are commercially available.
- Zultanski, Susan L.,Zhao, Jingyi,Stahl, Shannon S.
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supporting information
p. 6416 - 6419
(2016/06/09)
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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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- Stereocontrolled Synthesis of β-Lactams within [2]Rotaxanes: Showcasing the Chemical Consequences of the Mechanical Bond
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The intramolecular cyclization of N-benzylfumaramide [2]rotaxanes is described. The mechanical bond of these substrates activates this transformation to proceed in high yields and in a regio- and diastereoselective manner, giving interlocked 3,4-disubstituted trans-azetidin-2-ones. This activation effect markedly differs from the more common shielding protection of threaded functions by the macrocycle, in this case promoting an unusual and disfavored 4-exo-trig ring closure. Kinetic and synthetic studies allowed us to delineate an advantageous approach toward β-lactams based on a two-step, one-pot protocol: an intramolecular ring closure followed by a thermally induced dethreading step. The advantages of carrying out this cyclization in the confined space of a benzylic amide macrocycle are attributed to its anchimeric assistance.
- Martinez-Cuezva, Alberto,Lopez-Leonardo, Carmen,Bautista, Delia,Alajarin, Mateo,Berna, Jose
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supporting information
p. 8726 - 8729
(2016/07/30)
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- NHC-Catalyzed Benzylic Csp3–H Bond Activation of Alkylarenes and N-Benzylamines for the Synthesis of 3H-Quinazolin-4-ones: Experimental and Theoretical Study
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An N-heterocyclic carbene catalyzed benzylic Csp3–H bond activation of alkylarenes and N-benzylamines under metal-free conditions was developed. This organocatalyzed oxidative transformation afforded the corresponding carbonyl derivatives in good to excellent yields. A variety of alkylarenes and N-benzylamines were tolerated under the optimized reaction conditions. The established method was further extended to the synthesis of biologically important 3H-quinazolin-4-ones in good yields. For example, NPS 53574, a potent calcium receptor antagonist, was successfully synthesized by using this oxidative protocol. DFT studies show that the benzylic C–H bond activation proceeds through the nucleophilic attack of the free carbene on the benzylic carbon atom.
- Alanthadka, Anitha,Devi, E. Sankari,Nagarajan, Subbiah,Sridharan, Vellaisamy,Suvitha, Ambigapathy,Maheswari, C. Uma
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supporting information
p. 4872 - 4880
(2016/10/13)
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- Tf2O-TMDS combination for the direct reductive transformation of secondary amides to aldimines, aldehydes, and/or amines
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The direct partial reduction of highly stable secondary amides to more reactive aldimines and aldehydes is a challenging yet highly demanding transformation. In this context, only three methods have been reported. We report herein an improved version of the Charette’s method. Our protocol consists of activation of secondary amides with triflic anhydride/2-fluoropyridine, and partial reduction of the resulting intermediates with 1,1,3,3-tetramethyldisiloxane (TMDS), which delivered aldimines or aldehydes upon acidic hydrolysis. Aromatic amides were reduced to the corresponding aldimines in 85%–100% NMR yields, and yields (NMR) from aliphatic amides were 72%–86%. Acidic hydrolysis of the aldimine intermediates afforded, in one-pot, the corresponding aldehydes in 80%–96% yields. A simple protocol was established to isolate labile aldimines in pure form in 92%–96% yields. The improved method gave generally higher yields as compared to the known ones, and features the use of cheaper and more atom-economical TMDS as a chemoselective reducing agent. In addition, a convenient extraction protocol has been established to allow the isolation of amines, which constitutes a mild method for the N-deacylation of amides, another highly desirable transformation. The extended method retains the advantages of the original method of Charette in terms of mild conditions, good functional group tolerance, and excellent chemoselectivity.
- Lang, Qi-Wei,Hu, Xiu-Ning,Huang, Pei-Qiang
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p. 1638 - 1644
(2016/12/07)
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- Load manganese oxidizing catalytic chipboard spreading method for one-step synthesis of imines
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The invention belongs to the technical fields of chemistry and chemical engineering, and concretely relates to a method for one step synthesis of imine through catalyzing alcohol and amine by supported manganese oxide. A reaction of alcohol and amine is carried out in a solvent or solvent-free state at 60-90DEG C for 6-48h with the supported manganese oxide as a catalyst and molecular oxygen or air as an antioxidant to realize one step synthesis of a corresponding imine compound. The valence of manganese in the catalyst is +2, +3 or +4, the general formula of the catalyst is MnOx, and a carrier is hydroxyapatite (Ca10(PO4)6(OH)2). The catalyst still has very good activity and selectivity after the catalyst is reused at least 9 times. The catalyst used in the method has the characteristics of simple preparation, cheapness, high reaction selectivity and environmental protection.
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Paragraph 0068; 0069
(2017/02/02)
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- Aerobic oxidative coupling of alcohols and amines to imines over iron catalysts supported on mesoporous carbon
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Direct oxidative coupling of an alcohol and amine, with air or molecular oxygen as the oxygen source, is an environmentally friendly method for imine synthesis. We developed an Fe catalyst supported on mesoporous carbon (denoted by FeOx/HCMK-3) for this reaction with excellent activity and recyclability. FeOx/HCMK-3 was prepared by impregnating HNO3-treated mesoporous carbon (CMK-3) with iron nitrate solution. The highly dispersed FeOx species give FeOx/HCMK-3 high reducibility and are responsible for the high catalytic performance. Imine synthesis over FeOx/HCMK-3 follows a redox mechanism. The oxygen species in FeOx/HCMK-3 participate in the reaction and are then regenerated by oxidation with molecular O2. The reaction involves two consecutive steps: oxidative dehydrogenation of an alcohol to an aldehyde and coupling of the aldehyde with an amine to give an imine. Oxidative dehydrogenation of the alcohol is the rate-determining step in the reaction.
- Geng, Longlong,Song, Jinling,Zheng, Bin,Wu, Shujie,Zhang, Wenxiang,Jia, Mingjun,Liu, Gang
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p. 1451 - 1460
(2016/10/04)
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- Coupling MOF-based photocatalysis with Pd catalysis over Pd@MIL-100(Fe) for efficient N-alkylation of amines with alcohols under visible light
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Pd nanoparticles with an average size of 1.7 nm confined inside a MIL-100(Fe) cavity (Pd@MIL-100(Fe)) were prepared via double-solvent impregnation combined with a photoreduction process. Due to efficient coupling of photocatalytic dehydrogenation and Pd-based hydrogenation, the resultant Pd@MIL-100(Fe) showed significantly superior performance in light-induced N-alkylation of amines with alcohols over Pd/MIL-100(Fe), in which larger Pd nanoparticles (6–12 nm) deposited on the external surface of MIL-100(Fe) were prepared via a conventional single-solvent impregnation followed by a similar photoreduction process. Kinetic studies and controlled experiments revealed that the whole N-alkylation reaction is limited by the photocatalytic alcohol-to-aldehyde dehydrogenation reaction. This is the first demonstration of light-induced N-alkylation of amines by alcohols over M/MOFs nanocomposites and also highlights the great potential of using M/MOFs nanocomposites as multifunctional catalysts for light-induced organic syntheses.
- Wang, Dengke,Li, Zhaohui
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p. 151 - 157
(2018/03/29)
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- A Solvent-Free Process for Synthesis of Imines by Iron-Catalyzed Oxidative Self- or Cross-Condensation of Primary Amines Using Molecular Oxygen as Sole Oxidant
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Abstract: The synthesis of imines by oxidative self- or cross-condensation of primary amines has been achieved using iron(II) bromide as the catalyst. The protocol is ligand-free, additive-free, solvent-free, and high-yielding and utilizes renewable oxygen as sole oxidant. The reaction tolerated a wide range of functionalities. Graphical Abstract: [Figure not available: see fulltext.]
- Gopalaiah, Kovuru,Saini, Anupama
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p. 1648 - 1654
(2016/08/30)
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- Novel transition bimetal-organic frameworks: Recyclable catalyst for the oxidative coupling of primary amines to imines at mild conditions
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A novel type of transition bimetal-organic frameworks was described as a heterogeneous catalyst for the oxidative coupling of amines to imines under mild conditions, which was easily synthesized by the coordination assembly of manganese(ii) and cobalt(ii) with 1,3,5-benzenetricarboxylic acid (H3BTC) for the first time. The metal-organic framework material was characterized by scanning electron microscopy, energy dispersive spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, thermogravimetry and N2 sorption. As an environmentally benign heterogeneous catalyst, the catalytic ability of the metal-organic framework material was then detected to be excellent for the tert-butyl hydroperoxide (TBHP) promoted direct oxidative coupling of benzylamines to imines in excellent yields (up to 100%) in methanol for 3 h. More importantly, it could be recycled up to six runs, while still maintaining its high catalytic activity.
- Ge, Danhua,Qu, Genlong,Li, Xinming,Geng, Kaiming,Cao, Xueqin,Gu, Hongwei
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p. 5531 - 5536
(2016/07/06)
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