- Nickel Catalyzed Imine Aldol Reactions between Activated Imines and Pronucleophiles
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Treatment of activated imines 1 with carbonyl compounds 2 in the presence of catalytic amounts of NiCl2(PPh3)2 or NiBr2(PPh3)2 at room temperature affords imine aldol products 3 in high to good yields.
- Shida, Naomi,Kubota, Yasufumi,Fukui, Hiroyuki,Asao, Naoki,Kadota, Isao,Yamamoto, Yoshinori
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- A new tool to guide halofunctionalization reactions: The halenium affinity (HalA) scale
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We introduce a previously unexplored parameter - halenium affinity (HalA)- as a quantitative descriptor of the bond strengths of various functional groups to halenium ions. The HalA scale ranks potential halenium ion acceptors based on their ability to stabilize a "free halenium ion". Alkenes in particular but other Lewis bases as well, such as amines, amides, carbonyls, and ether oxygen atoms, etc., have been classified on the HalA scale. This indirect approach enables a rapid and straightforward prediction of chemoselectivity for systems involved in halofunctionalization reactions that have multiple nucleophilic sites. The influences of subtle electronic and steric variations, as well as the less predictable anchimeric and stereoelectronic effects, are intrinsically accounted for by HalA computations, providing quantitative assessments beyond simple "chemical intuition". This combined theoretical-experimental approach offers an expeditious means of predicting and identifying unprecedented reactions.
- Ashtekar, Kumar Dilip,Marzijarani, Nastaran Salehi,Jaganathan, Arvind,Holmes, Daniel,Jackson, James E.,Borhan, Babak
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- Synthesis of β-Phosphinolactams from Phosphenes and Imines
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Various cis-β-phosphinolactams are synthesized stereoselectively for the first time from imines and diazo(aryl)methyl(diaryl)phosphine oxides under microwave irradiation. Diazo(aryl)methyl(diaryl)phosphine oxides first undergo the Wolf rearrangement to generate phosphenes. Imines nucleophilically attack the phosphenes followed by an intramolecular nucleophilic addition via less steric transition states to give final cis-β-phosphinolactams. C-Styrylimines generally give rise to β-phosphinolactams in higher yields than C-arylimines. The stereoselectivity and proposed mechanism are rationalized by DFT theoretical calculation.
- Fu, Xingyang,Li, Xinyao,Xu, Jiaxi
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supporting information
p. 8733 - 8737
(2021/11/17)
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- Iron-Catalyzed Hydrogen Transfer Reduction of Nitroarenes with Alcohols: Synthesis of Imines and Aza Heterocycles
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A straightforward and selective reduction of nitroarenes with various alcohols was efficiently developed using an iron catalyst via a hydrogen transfer methodology. This protocol led specifically to imines in 30-91% yields, with a good functional group tolerance. Noticeably, starting from o-nitroaniline derivatives, in the presence of alcohols, benzimidazoles can be obtained in 64-72% yields when the reaction was performed with an additional oxidant, DDQ, and quinoxalines were prepared from 1,2-diols in 28-96% yields. This methodology, unprecedented at iron for imines, also provides a sustainable alternative for the preparation of quinoxalines and benzimidazoles.
- Wu, Jiajun,Darcel, Christophe
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p. 1023 - 1036
(2021/01/09)
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- Stereoselective Construction of γ-Lactams via Copper-Catalyzed Borylacylation
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A versatile and highly stereoselective borylative cyclization to generate polyfunctionalized γ-lactams has been developed. The stereoselective synthesis of these key ring systems is crucial due to their ubiquity in natural products. We report the diastero- and enantioselective construction of di- and trisubstituted γ-lactam cores, with examples containing an enantioenriched quaternary carbon.
- Bajohr, Jonathan,Lautens, Mark,Polishchuk, Iuliia,Torelli, Alexa,Whyte, Andrew
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supporting information
p. 7915 - 7919
(2020/11/02)
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- Synthesis, characterization, molecular structure and computational study of tetrahedral pentamethylcyclopentadienyl iridacycle complexes with α,β-conjugated Schiff base ligands
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Due to the excellent catalytic activities and phosphorescent properties that iridium complexes display, iridium chemistry has been of great interest for scientific investigation over the past 30 years. Iridium metallacycle analogues (also known as an iridacycles) bearing phenylpyridine (ppy) ligands have been well reported on, whilst complexes with R-phenyl-(3-R-phenylallylidene)amine, which is an α,β-conjugated Schiff base ligand, have not had the same attention, despite the fact that both ligands share a similar coordination mode. In this research, four pentamethylcyclopentadienyl iridacycle complexes, Ir1a-Ir1d, with different α,β-conjugated Schiff base ligands were synthesized from a di-μ-chloro-dichloro-bis-(η5-pentamethylcyclopentadienyl)diiridium(III) precursor. The iridacycle complexes were characterized using spectroscopic techniques and the molecular structures of Ir1ab-Ir1d were determined using X-ray crystallography. The X-ray results revealed that the iridacycle complexes have a tetrahedral geometry, the iridium centre being coordinated through the N[dbnd]C[sbnd]Cα[dbnd]Cβ moiety of the α,β-conjugated Schiff base ligand. Computational calculations with the B3LYP method and with LanL2DZ basis sets indicated that the HOMO-LUMO energy gaps Ir1b-Ir1d were in the range 3.31–3.36 eV. The OMe substituent at the C terminal has a greater impact on the HOMO energy level than the one at the N terminal.
- Daud, Adibah Izzati,Khairul, Wan M.,Liu, Zhi-Qiang,Ong, Kok Tong,Tay, Meng Guan
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- Promoting Frustrated Lewis Pairs for Heterogeneous Chemoselective Hydrogenation via the Tailored Pore Environment within Metal–Organic Frameworks
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Frustrated Lewis pairs (FLPs) have recently been advanced as efficient metal-free catalysts for catalytic hydrogenation, but their performance in chemoselective hydrogenation, particularly in heterogeneous systems, has not yet been achieved. Herein, we demonstrate that, via tailoring the pore environment within metal–organic frameworks (MOFs), FLPs not only can be stabilized but also can develop interesting performance in the chemoselective hydrogenation of α,β-unsaturated organic compounds, which cannot be achieved with FLPs in a homogeneous system. Using hydrogen gas under moderate pressure, the FLP anchored within a MOF that features open metal sites and hydroxy groups on the pore walls can serve as a highly efficient heterogeneous catalyst to selectively reduce the imine bond in α,β-unsaturated imine substrates to afford unsaturated amine compounds.
- Niu, Zheng,Zhang, Weijie,Lan, Pui Ching,Aguila, Briana,Ma, Shengqian
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supporting information
p. 7420 - 7424
(2019/04/27)
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- Development of Chiral Spiro Phosphoramidites for Rhodium-Catalyzed Enantioselective Reactions
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A series of 1,1′-spirobiindane-7,7′-diol (SPINOL) analogues bearing a 2,2′-dimethyl-, cyclopentyl-, or cyclohexyl-fused ring were synthesized, and their distinct structural features were elucidated by X-ray crystallography. On the basis of these scaffolds, chiral monophosphoramidite ligands 6 a–m were synthesized, which demonstrated excellent enantioselectivity in RhI-catalyzed asymmetric hydrogenation of a dehydro amino acid methyl ester. Ligands 6 a–m were also successfully applied in the RhI-catalyzed enantioselective [4+2] cycloaddition of α,β-unsaturated imines with isocyanates, which afforded the corresponding pyrimidinones in good yields (60–92 %) with high enantioselectivities (75–92 % ee).
- Zheng, Zhiyao,Cao, Yuxi,Zhu, Dongsheng,Wang, Zheng,Ding, Kuiling
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supporting information
p. 9491 - 9497
(2019/04/08)
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- Heterogeneous Catalysis with Basic Compounds to Achieve the Synthesis and C-N Cleavage of Azetidin-2-ones under Microwave Irradiation
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The synthesis of azetidin-2-ones with a completely heterogeneous catalysis is reported. The use of basic compounds as solid catalysts allowed for the synthesis of azetidin-2-ones under microwave irradiation without organic additives such as triethylamine. An excellent catalyst for this transformation was Mg-Al hydroxide (MAH). The present methodology offers the advantages of non-hazardous reaction conditions, short reaction times, high yields, and catalyst reusability. Different substitution groups were tested on the imines and acyl chlorides to explore the scope of the reaction. Unconventional N-C4 bond cleavage was detected in azetidin-2-ones. MAH was characterized by N 2 adsorption-desorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HR-TEM).
- Alcaraz, Yolanda,Cruz, Francisco,De La Cruz, Fabiola N.,Delgado, Francisco,Domínguez, José Manuel,Galván, Adriana,Gomez, Clarisa Villegas,Martínez, Merced,Vázquez, Miguel A.
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supporting information
p. 3625 - 3637
(2019/09/30)
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- Stereoselective synthesis, spectroscopic and X-ray crystallographic characterization of novel trans- and cis-3-methylseleno substituted monocyclic β-lactams: Potential synthons for C-3 functionalized/bicyclic/halospiroseleno-β-lactams of medicinal interes
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New series of trans- and cis-3-methylseleno substituted β-lactams (4, 5) have been prepared from 2-methylselenoethanoic acid (2). The four-membered β-lactam ring was introduced by the condensation reaction between ketene retrieved from 2-methylselenoethan
- Bhalla, Aman,Nagpal, Yogesh,Berry, Shiwani,Narula, Dipika,Bari,Bhasin,Kumar, Rajeev
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p. 172 - 182
(2018/03/24)
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- Efficient Synthesis of Amines by Iron-Catalyzed C=N Transfer Hydrogenation and C=O Reductive Amination
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Here we report the catalytic transfer hydrogenation (CTH) of non-activated imines promoted by a Fe-catalyst in the absence of Lewis acid co-catalysts. Use of the (cyclopentadienone)iron complex 1, which is much more active than the classical ‘Kn?lker complex’ 2, allowed to reduce a number of N-aryl and N-alkyl imines in very good yields using iPrOH as hydrogen source. The reaction proceeds with relatively low catalyst loading (0.5–2 mol%) and, remarkably, its scope includes also ketimines, whose reduction with a Fe-complex as the only catalyst has little precedents. Based on this methodology, we developed a one-pot CTH protocol for the reductive amination of aldehydes/ketones, which provides access to secondary amines in high yield without the need to isolate imine intermediates. (Figure presented.).
- Facchini, Sofia Vailati,Cettolin, Mattia,Bai, Xishan,Casamassima, Giuseppe,Pignataro, Luca,Gennari, Cesare,Piarulli, Umberto
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supporting information
p. 1054 - 1059
(2018/01/27)
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- Synthesis, structure-activity relationships and preliminary mechanism study of N-benzylideneaniline derivatives as potential TLR2 inhibitors
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Toll-like receptor 2 (TLR2) can recognize pathogen-associated molecular patterns to defense against invading organisms and has been represents an attractive therapeutic target. Until today, none TLR2 small molecule antagonist have been developed in clinic
- Cai, Shaoyi,Zhu, Gengzheng,Cen, Xiaohong,Bi, Jingjie,Zhang, Jingru,Tang, Xiaoshan,Chen, Kun,Cheng, Kui
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p. 2041 - 2050
(2018/03/13)
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- Silylative Reductive Amination of α,β-Unsaturated Aldehydes: A Convenient Synthetic Route to β-Silylated Secondary Amines
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Described here is a reductive amination/hydrosilylation cascade of α,β-unsaturated aldehydes mediated by a Lewis acidic borane catalyst. The present reaction system provides an one-pot synthetic route towards β-silylated secondary amines that have not been accessible by other previous catalysis. Comparative 1H NMR studies on the silylative reduction of enimines revealed that steric bulkiness of primary amine reactants strongly affects both catalytic efficiency and regioselectivity. This strategy was applicable to a broad range of substrates and amenable to one-pot gram-scale synthesis. Moreover, a diastereoselective introduction of the β-silyl group was also found to be feasible (d.r. up to 71:29).
- Kim, Eunae,Park, Sehoon,Chang, Sukbok
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supporting information
p. 5765 - 5769
(2018/03/28)
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- First example of the cascade acylation/IMDAV/ene reaction sequence, leading to N-arylbenzo[f]isoindole-4-carboxylic acids possessing anti-viral activity
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The reaction between readily accessible N-aryl-3-phenylallylamines and maleic anhydride led to unexpected products – polysubstituted hydrogenated benzo[f]isoindole-4-carboxylic acids. This transformation proceeds through a previously unknown sequence of s
- Voronov, Alexander A.,Alekseeva, Kseniia A.,Ryzhkova, Elena A.,Zarubaev, Vladimir V.,Galochkina, Anastasia V.,Zaytsev, Vladimir P.,Majik, Mahesh S.,Tilve, Santosh G.,Gurbanov, Atash V.,Zubkov, Fedor I.
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supporting information
p. 1108 - 1111
(2018/03/06)
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- Asymmetric Petasis Borono-Mannich Allylation Reactions Catalyzed by Chiral Biphenols
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Chiral biphenols catalyze the asymmetric Petasis borono-Mannich allylation of aldehydes and amines through the use of a bench-stable allyldioxaborolane. The reaction proceeds via a two-step, one-pot process and requires 2–8 mole % of 3,3′-Ph2-BINOL as the optimal catalyst. Under microwave heating the reaction affords chiral homoallylic amines in excellent yields (up to 99 %) and high enantioselectivies (er up to 99:1). The catalytic reaction is a true multicomponent condensation reaction whereas both the aldehyde and the amine can possess a wide range of structural and electronic properties. Use of crotyldioxaborolane in the reaction results in stereodivergent products with anti- and syn-diastereomers both in good diastereoselectivities and enantioselectivities from the corresponding E- and Z-borolane stereoisomers.
- Jiang, Yao,Schaus, Scott E.
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supporting information
p. 1544 - 1548
(2017/02/05)
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- Modular access to vicinally functionalized allylic (thio)morpholinonates and piperidinonates by substrate-controlled annulation of 1,3-azadienes with hexacyclic anhydrides
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A modular substrate-controlled hexannulation of inherently promiscuous 1,3-azadienes with hexacyclic anhydrides, which affords versatile vicinally functionalized allylic lactams, in high yields, regio- and stereoselectivities is described.
- Braunstein, Hannah,Langevin, Spencer,Khim, Monique,Adamson, Jonathan,Hovenkotter, Katie,Kotlarz, Lindsey,Mansker, Brandon,Beng, Timothy K.
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supporting information
p. 8864 - 8872
(2016/10/03)
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- Zn-Catalyzed Enantio- and Diastereoselective Formal [4 + 2] Cycloaddition Involving Two Electron-Deficient Partners: Asymmetric Synthesis of Piperidines from 1-Azadienes and Nitro-Alkenes
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We report a catalytic asymmetric synthesis of piperidines through [4 + 2] cycloaddition of 1-azadienes and nitro-alkenes. The reaction uses earth abundant Zn as catalyst and is highly diastereo- and regioselective. A novel BOPA ligand (F-BOPA) confers high reactivity and enantioselectivity in the process. The presence of ortho substitution on the arenes adjacent to the bis(oxazolines) was found to be particularly impactful, due to limiting the undesired coordination of 1-azadiene to the Lewis acid and thus allowing the reaction to be carried out at lower temperature. A series of secondary kinetic isotope effect studies using a range of ligands implicates a stepwise mechanism for the transformation, involving an initial Michael-type addition of the imine to the nitro-alkene followed by a cyclization event. The stepwise mechanism obviates the electronic requirement inherent to a concerted mechanism, explaining the successful cycloaddition between two electron-deficient partners. (Chemical Equation Presented).
- Chu, John C. K.,Dalton, Derek M.,Rovis, Tomislav
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supporting information
p. 4445 - 4452
(2015/04/14)
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- Tetrahydroquinolines and benzazepines through catalytic diastereoselective formal [4 + 2]-cycloaddition reactions between donor-acceptor cyclopropenes and imines
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Regio- and diastereoselective Lewis acid catalyzed cycloaddition reactions between imines and donor-acceptor cyclopropenes generated from silyl-protected enoldiazoacetates provide direct access to stable cyclopropane-fused tetrahydroquinolines and, with cyclopropane ring opening under mild conditions, to 1H-benzazipine derivatives.
- Truong, Phong M.,Mandler, Michael D.,Zavalij, Peter Y.,Doyle, Michael P.
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supporting information
p. 3278 - 3281
(2013/07/26)
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- An efficient three-component synthesis of homoallylic amines catalysed by MgI2 etherate
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A three-component reaction of aldehydes, amines and allyltributylstannane was efficiently carried out to afford the corresponding homoallylic amine derivatives in the presence of 20 mol% of MgI2 etherate [(MgI 2?(OEt2)n] under mild and neutral reaction conditions in good to excellent yields.
- Wang, Yanping,Liu, Yingshuai,Hu, Shenghui,Zhang, Xingxian
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experimental part
p. 21 - 24
(2012/03/27)
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- One-pot sequence synthesis of azetidin-2-one using diethyl chlorophosphate
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A simple and convenient synthesis of 2-azetidinone derivatives from the reaction of a pre-mixture of amines and aldehydes with carboxylic acids in the presence of diethyl chlorophosphate by [2+2] cycloaddition reaction is described. Separation and purification of imines as intermediates were not required. The methodology is convenient and good to excellent yields of products were obtained with simple purification.
- Zarei, Maaroof
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experimental part
p. 118 - 120
(2012/05/04)
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- Transition metals in organic synthesis, Part 105.1 Synthesis of pyrroles by silver(I)-promoted oxidative cyclization
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Condensation of aromatic aldehydes with arylamines to form Schiff bases, and subsequent addition of trimethylsilylpropargylmagnesium bromide, leads to homopropargylamines which on silver(I)-promoted oxidative cyclization affords 1,2-diarylpyrroles. ARKAT-
- Agarwal, Sameer,Paessler, Ulrike,Knoelker, Hans-Joachim
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- Three-component reactions of CF3-substituted boranes, ethyl diazoacetate and imines
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Aryl(methoxy)(trifluoromethyl)boranes, generated in situ, readily react with ethyl diazoacetate and N-(4- methoxyphenyl)imines to give derivatives of β-amino acids. In this process, the electron-deficient borane reacts with the diazo compound followed by trapping of the intermediate boron enolate by the imine. The final products are predominantly produced as syn isomers.
- Elkin, Pavel K.,Levin, Vitalij V.,Dilman, Alexander D.,Struchkova, Marina I.,Arkhipov, Dmitry E.,Korlyukov, Alexander A.
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supporting information
p. 6216 - 6218,3
(2021/10/12)
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- Enantioselective rhodium-catalyzed [4 + 2] cycloaddition of α,β-unsaturated imines and isocyanates
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A [4 + 2] cycloaddition of α,β-unsaturated imines and isocyanates catalyzed by a phosphoramidite-rhodium complex provides pyrimidinones in good yields and high enantioselectivities.
- Oberg, Kevin M.,Rovis, Tomislav
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supporting information; experimental part
p. 4785 - 4787
(2011/05/16)
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- Chiral phosphoric acid-catalyzed enantioselective three-component Povarov reaction using enecarbamates as dienophiles: Highly diastereo- and enantioselective synthesis of substituted 4-aminotetrahydroquinolines
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A chiral phosphoric acid (5)-catalyzed three-component Povarov reaction of aldehydes 2, anilines 3, and enecarbamates 4 afforded cis-4-amino-2-aryl(alkyl)- 1,2,3,4-tetrahydroquinolines 1 in high yields with excellent diastereoselectivities (>95%) and almost complete enantioselectivities (up to >99% ee). The reaction was applicable to a wide range of anilines bearing electron-donating (OMe) and electron-withdrawing groups (e.g., Cl, CF 3, NO2) and allowed, for the first time, aliphatic aldehydes to be employed in the enantioselective Povarov reaction. With β-substituted acyclic enecarbamates, 2,3,4-trisubstituted 1,2,3,4-tetrahydroquinolines with three contiguous stereogenic centers were produced in excellent diastereo- and enantioselectivities (87 to >99% ee). A detailed study of the active catalytic species allowed us to reduce the catalyst loading from 10% to 0.5% with no deterioration of enantiomeric excess. In addition, mechanistic studies allowed us to conclude unequivocally that the Povarov reaction involving enecarbamate as dienophile proceeded via a stepwise mechanism. The key role of the free NH function of the enecarbamate in the success of this transformation was demonstrated. NMR experiments indicating the catalyst-substrate interaction as well as a linear correlation between catalyst and product ee's were also documented.
- Dagousset, Guillaume,Zhu, Jieping,Masson, Geraldine
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supporting information; experimental part
p. 14804 - 14813
(2011/11/04)
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- GREEN SYNTHESIS OF ARYL ALDIMINES USING ETHYL LACTATE
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The present invention relates to a method for preparing aryl aldimines. In particular, the present invention relates to methods of preparing aryl aldimines that uses environmentally friendly solvent systems.
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Page/Page column 4-5
(2011/08/22)
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- Ethyl lactate as a tunable solvent for the synthesis of aryl aldimines
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Ethyl L-lactate can be tuned with a cosolvent to create polarity conditions ideal for synthesizing aryl aldimines that crystallize directly out of solution within minutes under ambient conditions in excellent yields and requiring no further purification.
- Bennett, Jacqueline S.,Charles, Kaitlyn L.,Miner, Matthew R.,Heuberger, Caitlin F.,Spina, Elijah J.,Bartels, Michael F.,Foreman, Taylor
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body text
p. 166 - 168
(2010/04/22)
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- The Vilsmeier reagent: a useful and versatile reagent for the synthesis of 2-azetidinones
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(Chloromethylene)dimethylammonium chloride (Vilsmeier reagent), prepared easily from N,N-dimethylformamide and oxalyl chloride or thionyl chloride, works as a versatile acid activator reagent for the direct [2+2] ketene-imine cycloaddition of substituted
- Jarrahpour, Aliasghar,Zarei, Maaroof
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experimental part
p. 2927 - 2934
(2009/05/30)
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- Accessing the amide functionality by the mild and low-cost oxidation of imine
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Oxidation of imines using sodium chlorite under buffered conditions gave the corresponding amides in good to high yield. The reaction was generally fast and was completed within 5-40 min. As has been established in the corresponding oxidation of aldehyde, so-called Pinnick oxidation, the good functional group tolerance and the use of inexpensive reagents are the advantages of this protocol.
- Mohamed, Magdi A.,Yamada, Ken-ichi,Tomioka, Kiyoshi
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supporting information; experimental part
p. 3436 - 3438
(2009/09/25)
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- Staudinger/aza-Wittig reactions utilizing a novel linear polymer-supported triphenylphosphine as a modified liquid-phase reagent
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A new triphenylphosphine reagent linked to a linear maleimide-styrene copolymer is synthesized and is found to be effective for the formation of a variety of imines via the Staudinger/aza-Wittig reaction. This linear polymer-supported triphenylphosphine h
- Mahdavi, Hossein,Amani, Javad
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experimental part
p. 5923 - 5926
(2010/01/11)
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- Studies on the bisoxazoline- and (-)-sparteine-mediated enantioselective addition of organolithium reagents to imines
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The enantioselective addition of organolithium reagents to N-anisylaldimines promoted by chiral bisoxazolines and (-)-sparteine as external ligands is described. This reaction proceeds readily with a wide range of aldimine substrates (aliphatic, aromatic, olefinic) and organolithium nucleophiles (Me, n-Bu, Ph, vinyl) in excellent yields (81-99%) and with high enantioselectivities (up to 97:3.0 er). The external ligands can be used in substoichiometric amounts albeit with slightly attenuated enantioselectivities. A systematic evaluation of the structural features of the bisoxazolines revealed a primary contribution from the substituent at C(4) and a secondary influence from the bridging substituents. A computational analysis (PM3) provided a clear rationalization for the origin of enantioselectivity.
- Denmark, Scott E.,Nakajima, Noriyuki,Stiff, Cory M.,Nicaise, Olivier J.-C.,Kranz, Michael
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experimental part
p. 1023 - 1045
(2009/05/30)
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- Proline-mediated enantioselective construction of tetrahydropyridines via a cascade Mannich-type/intramolecular cyclization reaction
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A highly diastereo- and enantioselective synthesis of 2,3-disubstituted tetrahydropyridines was accomplished via a proline-mediated cascade Mannich-type/intramolecular cyclization reaction from preformed N-PMP (p-methoxyphenyl) aldimines and inexpensive aqueous tetrahydro-2H-pyran-2,6- diol.
- Han, Rong-Gang,Wang, Yao,Li, Yu-Ye,Xu, Peng-Fei
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supporting information; experimental part
p. 1474 - 1478
(2009/07/18)
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- Cu(OTf)2 or Et3N-catalyzed three-component condensation of aldehydes, amines and cyanides: a high yielding synthesis of α-aminonitriles
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Copper(II) triflate or Et3N have been found to catalyze, under ambient conditions, the addition of a cyanide anion, such as trimethylsilyl cyanide or acetone cyanohydrin, onto in situ generated imines, furnishing α-aminonitriles in excellent yi
- Paraskar, Abhimanyu S.,Sudalai, Arumugam
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p. 5759 - 5762
(2007/10/03)
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- Free radical synthesis of benzofused tricyclic β-lactams by intramolecular cyclization of 2-azetidinone-tethered haloarenes
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o-Halogenophenyl- and o-halogenobenzyl-4-alkenyl-β-lactams can be prepared both in the racemic form and in optically pure form using the ketene-imine cyclization. These 2-azetidinone-tethered haloarenes were used for the regio- and stereoselective prepara
- Alcaide, Benito,Almendros, Pedro,Rodríguez-Vicente, Alberto,Ruiz, M. Pilar
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p. 2767 - 2778
(2007/10/03)
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- Palladium-catalyzed allylation of imines with allyl alcohols
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(Chemical Equation Presented) A catalytic system, Pd(OAc)2 (10 mol %)-P(n-Bu)3 (20 mol %)-Et3B (360 mol %), promotes allylic alcohols to undergo the allylation of anisidineimines of aromatic and aliphatic aldehydes and furnishes homoallylamines in good to moderate yields. The reaction shows unique stereoselectivity, giving anti-isomers selectively.
- Shimizu, Masamichi,Kimura, Masanari,Watanabe, Toshiya,Tamaru, Yoshinao
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p. 637 - 640
(2007/10/03)
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- Microwave-assisted rapid and simplified hydrogenation
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Catalytic transfer hydrogenation has been conducted under microwave irradiation in open vessels using high-boiling solvents such as ethylene glycol (bp 198 °C) as the microwave energy transfer agent. Reduction of double bonds and hydrogenolysis of several functional groups were carried out safely and rapidly (3-5 min) at about 110-130 °C with 10% Pd/C as an efficient catalyst and ammonium formate as the hydrogen donor. Diverse types of β-lactam synthons were prepared by the reduction of ring substituents containing alkene and alkylidene groups or conjugated unsaturated esters. Cleavage of the β-lactam ring by hydrogenolysis of the N-C4 bond of 4- aryl-2-azetidinones was a facile reaction with 10% Pd/C as the catalyst; but no ring scission occurred when Raney nickel catalyst was employed. Dehalogenation of aromatic compounds was also successful with ammonium formate and Pd/C catalyst. Hydrogenolysis of phenylhydrazone of methyl benzoylformate gave the methyl ester of phenylglycine in excellent yield. The techniques described here for microwave assisted hydrogenation are safe, rapid, and efficient and are suitable for research investigation as well as for undergraduate and high school laboratory exercises.
- Banik, Bimal K.,Barakat, Khaled J.,Wagle, Dilip R.,Manhas, Maghar S.,Bose, Ajay K.
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p. 5746 - 5753
(2007/10/03)
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- Stereoisomeric Styryl-substituted Pyrrolidines, 3,7-Diazobicyclo[3.3.0]octanes and 2-Styrylpyrroles from Cinnamaldehyde Iminium-N-methanide 1,3-Dipoles
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The reaction of cinnamaldehyde N-aryliminium methanide 1,3-dipoles with dimethyl maleate, dimethyl fumarate and some N-arylmaleimides gives equal mixtures of stereoisomeric substituted pyrrolidines and a route to 2-styrylpyrroles with dimethyl acetylene-d
- Butler, Richard N.,Farrell, Derval M.
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- Anti-tumor compounds, pharmaceutical compositions, methods for preparation thereof and for treatment
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The present invention is directed to novel taxanes useful as chemotherapeutic agents or their precursors. Processes for preparing the novel taxanes include coupling reactions, in the presence of a base, of baccatin of formula (III) or (IV) STR1 with β-lac
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- Stereoselectivity in the Condensation Reactions between Malate Enolate and Imines to 2-Pyrrolidinone Derivatives
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Enolate dianion of diethyl (S)-malate was stereoselectively condensed with nonenolizable N-arylimines to give 2-pyrrolidinone derivatives.The presence of HMPA changes the diastereoselectivity of this cyclization reaction.
- Ha, Deok-Chan,Yun, Kyeong-Soon,Park, Hye-Sang,Choung, Won-Keun,Kwon, Young-Eun
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p. 8445 - 8448
(2007/10/02)
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- Anti-tumor compounds, pharmaceutical compositions, methods for preparation thereof and for treatment
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The present invention is directed to novel taxanes useful as chemotherapeutic agents or their precursors. Processes for preparing the novel taxanes include coupling reactions, in the presence of a base, of baccatin of formula (III) or (IV) STR1 with β-lac
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- Process for the production of chiral hydroxy-β-lactams and hydroxyamino acids derived therefrom
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The reaction between a hydroxyacetic acid derivative bearing an oxygen protecting group and a chiral auxiliary group and an imine produces chiral β-lactams. Hydrolysis of the chiral β-lactams produces chiral amino acid analogs.
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- Chemistry of Mucohalic Acids, VII. - Asymmetric Synthesis of β-Lactam Derivatives by the Ketene-Imine Cycloaddition Utilizing Chiral Mucohalic Acid Derivatives
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The ketene derivative 5 of the chiral pyrrolinone 4 underwent nonconcerted cycloadditions with imines leading to cis-β-lactams 6a-d with 99percent diastereoisomeric excess. rac-4 was resolved efficiently by crystallisation of diastereoisomeric a
- Duczek, Wolfram,Jaehnisch, Klaus,Kunath, Annamarie,Reck, Guenter,Winter, Gabriele,Schulz, Burkhard
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p. 781 - 788
(2007/10/02)
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- New and efficient approaches to the semisynthesis of taxol and its C-13 side chain analogs by means of β-lactam synthon method
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Highly efficient chiral ester enolate-imine condensation giving 3-hydroxy-4-aryl-β-lactams with excellent enantiomeric purity is successfully applied to the asymmetric synthesis of the enantiomerically pure taxol C-13 side chain, N-benzoyl-(2R,3S)-3-phenyl-isoserine and its analogs. (3R,4S)-N-benzoyl-3-(1-ethoxyethoxy)-4-phenyl-2-azetidinone readily derived from the 3-hydroxy-4-phenyl-β-lactam is coupled with protected baccatin IIIs, followed by deprotection to give optically pure taxol and 10-deacetyl-7,10-bis(Troc)-taxol in good yields. Fully assigned 1H, 13C, and 2D (COSY and HETCOR) NMR spectra of taxol thus synthesized are shown and discussed.
- Ojima, Iwao,Habus, Ivan,Zhao, Mangzhu,Zucco, Martine,Park, Young Hoon,Sun, Chung Ming,Brigaud, Thierry
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p. 6985 - 7012
(2007/10/02)
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- Reaction of Reissert Anion with Aldimines: A New Approach to the Imidazoisoquinoline Ring System
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The carbanion derived from N-alkoxycarbonyl Reissert compound readily undergoes addition-cyclization reaction with aldimines to give imidazoisoquinolines.A detailed study of this new ring annelation chemistry is described.
- Kant, Joydeep
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p. 2129 - 2132
(2007/10/02)
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- Synthesis of organophosphorus compounds via silyl esters of phosphorous acids
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The addition of trimethylsilyloxy phosphorus (III)derivatives generated in situ to imines at room temperature provides a mild selective and high yielding route to α-aminoalkylphosphorate and α-aminoalkylphenylphosphinate esters. Isocyanates and carbodiimides react similarly to give phosphonoureas and phosphonoguarnidines respectively aldehydes and ketones are much less reactive and cyanides are inert.
- Afarinkia, Kamyar,Rees, Charles W.,Cadogan, John I. G.
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p. 7175 - 7196
(2007/10/02)
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- The Reaction of α,β-Unsaturated Aldimines with Benzofuroxan
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Benzofuroxan reacts with imines derived from crotonaldehyde and cinnamaldehyde, to form 2-iminomethylquinoxaline 1,4-dioxides.
- Devi, Purabi,Sandhu, Jagir S.
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p. 427 - 428
(2007/10/02)
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- Ruthenium-catalysed Oxidation of Secondary Amines to Imines using t-Butyl Hydroperoxide
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The ruthenium-catalysed oxidation of secondary amines with t-butyl hydroperoxide under mild conditions affords the corresponding imines in high yields.
- Murahashi, Shun-Ichi,Naota, Takeshi,Taki, Hiroshi
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p. 613 - 614
(2007/10/02)
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- Synthesis of New Polycyclic Carbazoloquinones
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Some new policyclic carbazoloquinones, substituted 6H-pyridocarbazoles (V) have been synthesized by the interaction of the Diels-Alder adducts (II), obtained from the addition of cinnamyliden-anils (I) to 4,4-dimethoxyquinone in 1:1 molar ratio, wi
- Hammam, A. S.,Youssef, M. S. K.,Abbady, M. A.,Ibrahim, R. R.
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p. 565 - 570
(2007/10/02)
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