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Search for "organocatalysts" in Full Text gives 176 result(s) in Beilstein Journal of Organic Chemistry.

New α- and β-cyclodextrin derivatives with cinchona alkaloids used in asymmetric organocatalytic reactions

  • Iveta Chena Tichá,
  • Simona Hybelbauerová and
  • Jindřich Jindřich

Beilstein J. Org. Chem. 2019, 15, 830–839, doi:10.3762/bjoc.15.80

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  • , Czech Republic 10.3762/bjoc.15.80 Abstract The preparation of new organocatalysts for asymmetric syntheses has become a key stage of enantioselective catalysis. In particular, the development of new cyclodextrin (CD)-based organocatalysts allowed to perform enantioselective reactions in water and to
  • ; cinchona alkaloids; CuAAC click reaction; cyclodextrin; organocatalysts; Introduction Cyclodextrins (CDs) [1], cyclic oligosaccharides consisting of α-D-glucopyranoside units, and their derivatives are widely used in many industrial and research areas for their ability to form supramolecular inclusion
  • as the promoter (not in a catalytic amount) of a Henry reaction and obtained the product with 99% ee. Subsequently, Doyagüez et al. [17] attached L-proline to β-CD via different linkers (including a triazole linker) and used the resulting organocatalysts in an aldol reaction in water, albeit with a
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Published 01 Apr 2019

A diastereoselective approach to axially chiral biaryls via electrochemically enabled cyclization cascade

  • Hong Yan,
  • Zhong-Yi Mao,
  • Zhong-Wei Hou,
  • Jinshuai Song and
  • Hai-Chao Xu

Beilstein J. Org. Chem. 2019, 15, 795–800, doi:10.3762/bjoc.15.76

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  • the biaryls with good to excellent central-to-axial chirality transfer. Keywords: axial chirality; biaryl; electrochemistry; oxidation; radical; Introduction Axially chiral biaryls are prevalent in natural products, bioactive molecules and organocatalysts [1][2]. Among the many methods that have
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Letter
Published 28 Mar 2019

Thiol-free chemoenzymatic synthesis of β-ketosulfides

  • Adrián A. Heredia,
  • Martín G. López-Vidal,
  • Marcela Kurina-Sanz,
  • Fabricio R. Bisogno and
  • Alicia B. Peñéñory

Beilstein J. Org. Chem. 2019, 15, 378–387, doi:10.3762/bjoc.15.34

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  • thiols (Scheme 1) [17][18][19][20][21], other methodologies employing different sulfur sources such as disulfides or silylsulfides have been described, which most of them involves metals, e.g., indium [22], copper [23], mercury [24], or organocatalysts [25]. β-Ketosulfides, in addition, play an important
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Published 11 Feb 2019

Tandem copper and photoredox catalysis in photocatalytic alkene difunctionalization reactions

  • Nicholas L. Reed,
  • Madeline I. Herman,
  • Vladimir P. Miltchev and
  • Tehshik P. Yoon

Beilstein J. Org. Chem. 2019, 15, 351–356, doi:10.3762/bjoc.15.30

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  • transition metals, Lewis acids, and organocatalysts has been productively utilized in asymmetric transformations [7][8][9], cross-couplings [10][11][12], and oxidative decarboxylation reactions [13][14], among others. The use of a cocatalyst to control these photochemical transformations enables reactions
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Published 05 Feb 2019

Organometallic vs organic photoredox catalysts for photocuring reactions in the visible region

  • Aude-Héloise Bonardi,
  • Frédéric Dumur,
  • Guillaume Noirbent,
  • Jacques Lalevée and
  • Didier Gigmes

Beilstein J. Org. Chem. 2018, 14, 3025–3046, doi:10.3762/bjoc.14.282

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  • oxidative and reductive cycle can be observed and the two routes are even in competition and occur simultaneously. This is reinforced by remarkably long lifetime excited state (Table 8). In organic chemistry, TADF molecules can also be used as organocatalysts for classical organic reactions that are
  • hydrocarbons [93], heteropolyacenes [90][91], carbazoles [80][81][94], triazines [95], pentacenes [96], diketopyrrolopyrroles [24] and perylene [97][98] derivatives have been investigated as organocatalysts as exemplified in Scheme 5. 3 Comparison of the efficiency of these photoredox catalysts in
  • cycles involved with iodonium salt and (A) (TMS)3SiH, (B) NVK and (C) EDB. Structures of additives involved in the photoredox catalytic cycles. Structures of photoredox metal-based catalysts. Photocatalytical cycle for the Ru complex. Structures of photoredox organocatalysts. Diversity of the chemical
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Published 12 Dec 2018

Enhanced single-isomer separation and pseudoenantiomer resolution of new primary rim heterobifunctionalized α-cyclodextrin derivatives

  • Iveta Tichá,
  • Gábor Benkovics,
  • Milo Malanga and
  • Jindřich Jindřich

Beilstein J. Org. Chem. 2018, 14, 2829–2837, doi:10.3762/bjoc.14.261

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  • selected positions remains a challenging task because of the similar reactivity of the hydroxy groups. Nevertheless, selectively disubstituted CD derivatives are used to prepare artificial enzymes [4][5], metallocatalysts and organocatalysts [6][7][8] or amino acid mimics [9]. Among the methods used to
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Published 13 Nov 2018

Asymmetric Michael addition reactions catalyzed by calix[4]thiourea cyclohexanediamine derivatives

  • Zheng-Yi Li,
  • Hong-Xiao Tong,
  • Yuan Chen,
  • Hong-Kui Su,
  • Tangxin Xiao,
  • Xiao-Qiang Sun and
  • Leyong Wang

Beilstein J. Org. Chem. 2018, 14, 1901–1907, doi:10.3762/bjoc.14.164

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  • and yields of the Michael reactions. Supramolecular catalysis has drawn tremendous interest in the past few years [15][16][17][18][19][20][21][22][23]. In this context, calixarenes are ideal supramolecular macrocyclic scaffolds for the design of molecular receptors and organocatalysts due to their
  • reactions in aqueous solution with excellent enantioselectivity [35]. As part of our ongoing studies to develop novel types of organocatalysts for asymmetric catalysis, in this study, we aimed to synthesize novel upper rim-functionalized calix[4]thiourea cyclohexanediamine derivatives to catalyze asymmetric
  • the new chiral amino-substituted thioureas [33][39]. For this, the Michael addition reaction of acetylacetone (8) to β-nitrostyrene (7a) was chosen as the model reaction to evaluate the efficiency of compounds 1–4 as chiral organocatalysts (Table 1, entries 1–4). From Table 1, it can be seen that the
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Published 25 Jul 2018

Thiocarbonyl-enabled ferrocene C–H nitrogenation by cobalt(III) catalysis: thermal and mechanochemical

  • Santhivardhana Reddy Yetra,
  • Zhigao Shen,
  • Hui Wang and
  • Lutz Ackermann

Beilstein J. Org. Chem. 2018, 14, 1546–1553, doi:10.3762/bjoc.14.131

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  • motifs of powerful transition metal catalyst ligands and organocatalysts (Figure 1) [94][95][96][97]. During the preparation of this article, the use of strongly-coordinating, difficult to remove directing groups has been reported [70][71]. In sharp contrast, notable features of our approach include (i
  • thermal fashion as well as by means of mechanochemistry, providing access to synthetically meaningful aminoketones. Selected ferrocene-based ligands and organocatalysts. Scope of substituted dioxazolones 2. C–H Amidation of arylated ferrocenes 1. Thiocarbonyl-assisted C–H amidation. H/D Exchange reactions
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Published 25 Jun 2018

Hypervalent organoiodine compounds: from reagents to valuable building blocks in synthesis

  • Gwendal Grelier,
  • Benjamin Darses and
  • Philippe Dauban

Beilstein J. Org. Chem. 2018, 14, 1508–1528, doi:10.3762/bjoc.14.128

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  • investigated and significant achievements have been reported making iodine compounds now useful organocatalysts in asymmetric synthesis (reaction 2 in Scheme 1a) [15][16][17][18][19][20][21][22][23][24]. In parallel to these investigations, a third strategy has been envisaged with the development of tandem
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Published 21 Jun 2018

Recent applications of chiral calixarenes in asymmetric catalysis

  • Mustafa Durmaz,
  • Erkan Halay and
  • Selahattin Bozkurt

Beilstein J. Org. Chem. 2018, 14, 1389–1412, doi:10.3762/bjoc.14.117

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  • -cyclohepten-1-one and chalcone were also tested as substrates for the Michael addition reaction and the corresponding adducts were obtained in good yield with moderate enantioselectivity (13–23% ee). Calixarene-derived thiourea seemed to be an interesting backbone for design of new organocatalysts for
  • series of calixarene-based chiral bifunctional tertiary amine–thiourea organocatalysts 54–56 have been synthesized by us and Genc et al. (Scheme 15) [52][53]. Among them, 54a,b were applied to the asymmetric Michael addition of 1,3-dicarbonyl compounds 34 and 57 to a variety of nitroolefins. Although
  • . reported the synthesis of a series of prolinamide and hydroxyprolinamide organocatalysts based on the calix[4]arene scaffold (Figure 8) [59]. Treatment of Boc-protected-L-proline or hydroxyproline with various aminocalix[4]arenes under one of the appropriate coupling conditions and subsequent deprotection
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Published 08 Jun 2018

Synthesis of chiral 3-substituted 3-amino-2-oxindoles through enantioselective catalytic nucleophilic additions to isatin imines

  • Hélène Pellissier

Beilstein J. Org. Chem. 2018, 14, 1349–1369, doi:10.3762/bjoc.14.114

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  • –Hillman reactions, Friedel–Crafts reactions, aza-Henry reactions, domino reactions initiated by nucleophilic additions to isatin imines, and miscellaneous reactions. Most of the reactions depicted in this review have been promoted by a wide variety of chiral organocatalysts but chiral metal catalysts have
  • ]. An extensively used two-component variant of this reaction consists in using a preformed imine. Among chiral metal complexes, a wide variety of organocatalysts [26][27][28][29][30][31][32][33][34] has been used to promote asymmetric Mannich reactions. Among them, cinchona alkaloid 1 was employed in
  • , ECA109 and BT474 cancer cell lines. Metal-catalyzed reactions In addition to organocatalysts, chiral metal catalysts [41][42][43][44][45][46][47] have been recently applied to promote enantioselective Mannich reactions. As an example, in 2015 Feng et al. reported the enantioselective Mannich reaction of
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Published 06 Jun 2018

2-Iodo-N-isopropyl-5-methoxybenzamide as a highly reactive and environmentally benign catalyst for alcohol oxidation

  • Takayuki Yakura,
  • Tomoya Fujiwara,
  • Akihiro Yamada and
  • Hisanori Nambu

Beilstein J. Org. Chem. 2018, 14, 971–978, doi:10.3762/bjoc.14.82

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  • iodobenzene and 4-iodobenzenesulfonic acid (12) as catalysts [58][59]. As part of our study on the development of multifunctionalized organocatalysts based on hypervalent iodine chemistry [60][61][62][63][64][65][66], we found that N-isopropyl-2-iodobenzamide (13), when utilized as a catalyst with Oxone® at
  • partially supported by a Grant-in-Aid for Scientific Research on Innovative Areas “Advanced Molecular Transformations by Organocatalysts” from the Ministry of Education, Culture, Sports, Science and Technology, Japan; JSPS Core-to-Core Program, B. Asia-Africa Science Platforms; and Toyama Prefecture
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Published 30 Apr 2018

Nanoreactors for green catalysis

  • M. Teresa De Martino,
  • Loai K. E. A. Abdelmohsen,
  • Floris P. J. T. Rutjes and
  • Jan C. M. van Hest

Beilstein J. Org. Chem. 2018, 14, 716–733, doi:10.3762/bjoc.14.61

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  • (enzymes), organocatalysts and metal catalysts [47]. Catalysis is defined as heterogeneous when catalysts are in an aggregated state, and are thus in a different phase than the reactants [27][48]. Heterogeneous catalysts typically consist of a solid carrier, the so called “support”, on which catalytic
  • hydrophobic and aqueous compartments, they are especially useful for the immobilization of different catalysts, such as organocatalysts and enzymes that require different microenvironments for their optimal performance. 3. Covalent systems 3.1. Dendrimers Dendrimers are a class of highly branched molecules
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Published 29 Mar 2018

Diastereoselective auxiliary- and catalyst-controlled intramolecular aza-Michael reaction for the elaboration of enantioenriched 3-substituted isoindolinones. Application to the synthesis of a new pazinaclone analogue

  • Romain Sallio,
  • Stéphane Lebrun,
  • Frédéric Capet,
  • Francine Agbossou-Niedercorn,
  • Christophe Michon and
  • Eric Deniau

Beilstein J. Org. Chem. 2018, 14, 593–602, doi:10.3762/bjoc.14.46

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  • reactions implying the use of a chiral auxiliary resulted effectively in various optically pure compounds [10][18][19][20]. Second, enantioselective syntheses of these bicylic lactams were performed by using chiral transition metal- or organocatalysts which control the configuration of the trisubstituted
  • , substituted at the benzyl para-position by isopropyl and CF3 groups, gave good results with 76 and 74% de (Table 2, entries 9 and 10). Dimeric and trimeric organocatalysts 19 and 20 based on a cinchonine core did not enhance the reaction diastereoselectivity (Table 2, entries 15 and 16). Finally, by
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Published 09 Mar 2018

Investigations towards the stereoselective organocatalyzed Michael addition of dimethyl malonate to a racemic nitroalkene: possible route to the 4-methylpregabalin core structure

  • Denisa Vargová,
  • Rastislav Baran and
  • Radovan Šebesta

Beilstein J. Org. Chem. 2018, 14, 553–559, doi:10.3762/bjoc.14.42

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  • catalyst. Furthermore, specific organocatalysts can provide respective stereoisomers of the key Michael adduct in up to 99:1 er. Keywords: kinetic resolution; Michael addition; organocatalysis; pregabalin; squaramide; Introduction Asymmetric organocatalysis has considerably broadened possibilities for
  • malonate catalyzed by hydrogen-bond-donating organocatalysts (Scheme 2). We have also briefly investigated Meldrum´s acid as a donor, instead of dimethyl malonate, but we have obtained a complicated reaction mixture, which was difficult to purify. Therefore, we have focused our attention on the Michael
  • addition of dimethyl malonate. An initial catalyst screening was performed in dichloromethane, based on our previous experiences with this type of Michael additions [18]. We have employed a range of squaramide and thiourea organocatalysts C1–C7 [18][27][28][29][30][31][32][33][34], as well as two newly
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Published 05 Mar 2018

Novel amide-functionalized chloramphenicol base bifunctional organocatalysts for enantioselective alcoholysis of meso-cyclic anhydrides

  • Lingjun Xu,
  • Shuwen Han,
  • Linjie Yan,
  • Haifeng Wang,
  • Haihui Peng and
  • Fener Chen

Beilstein J. Org. Chem. 2018, 14, 309–317, doi:10.3762/bjoc.14.19

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  • Lingjun Xu Shuwen Han Linjie Yan Haifeng Wang Haihui Peng Fener Chen Department of Chemistry, Fudan University, Shanghai 200433, PR China 10.3762/bjoc.14.19 Abstract A family of novel chloramphenicol base-amide organocatalysts possessing a NH functionality at C-1 position as monodentate hydrogen
  • bond donor were developed and evaluated for enantioselective organocatalytic alcoholysis of meso-cyclic anhydrides. These structural diversified organocatalysts were found to induce high enantioselectivity in alcoholysis of anhydrides and was successfully applied to the asymmetric synthesis of (S
  • )-GABOB. Keywords: alcoholysis desymmetrization; bifunctional organocatalysis; chloramphenicol base; Introduction Over the past decade, remarkable advances in the utilization of natural products as chiral structural motifs for the design of bifunctional organocatalysts have been achieved. A high
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Published 31 Jan 2018

Quinone-catalyzed oxidative deformylation: synthesis of imines from amino alcohols

  • Xinyun Liu,
  • Johnny H. Phan,
  • Benjamin J. Haugeberg,
  • Shrikant S. Londhe and
  • Michael D. Clift

Beilstein J. Org. Chem. 2017, 13, 2895–2901, doi:10.3762/bjoc.13.282

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  • decarboxylative homologation of α-amino acids [32], which demonstrated for the first time that quinone organocatalysts can be utilized to enable oxidative C–C bond cleavage to provide versatile imine intermediates. To further exploit the utility of this chemistry, we sought to develop a new method for the
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Published 28 Dec 2017

Binding abilities of a chiral calix[4]resorcinarene: a polarimetric investigation on a complex case of study

  • Marco Russo and
  • Paolo Lo Meo

Beilstein J. Org. Chem. 2017, 13, 2698–2709, doi:10.3762/bjoc.13.268

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  • in general have been proven excellent stereoselective organocatalysts [33][34][35][36][37][38][39][40]. In particular, CA derivatives bearing proline units (on both the upper and the lower rim) have been tested as catalysts for asymmetric aldol reactions in water [28][29][30][33]. Similar derivatives
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Published 15 Dec 2017

Synthesis of 1,3-cis-disubstituted sterically encumbered imidazolidinone organocatalysts

  • Jan Wallbaum and
  • Daniel B. Werz

Beilstein J. Org. Chem. 2017, 13, 2577–2583, doi:10.3762/bjoc.13.254

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  • Jan Wallbaum Daniel B. Werz Institut für Organische Chemie, Technische Universität Braunschweig, Hagenring 30, 38106 Braunschweig, Germany 10.3762/bjoc.13.254 Abstract A variety of novel imidazolidinone-based organocatalysts with bulky substituents were synthesized under mild reaction conditions
  • ][3][4][5][6][7]. Initially, proline and proline-derived catalysts have been widely used in asymmetric iminium and enamine organocatalysis [8][9][10][11][12]. Since the beginning of the 21th century imidazolidinone-based organocatalysts developed by MacMillan and co-workers, which are easily
  • enamine complex. Scheme 1b shows our regio-, diastereo- and enantioselective 1,3-chlorosulfenation of meso-cyclopropyl carbaldehydes employing a newly designed organocatalyst 7a·DCA for chiral induction [25]. In the course of these studies we prepared a variety of imidazolidinone organocatalysts with
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Published 01 Dec 2017

Electron-deficient pyridinium salts/thiourea cooperative catalyzed O-glycosylation via activation of O-glycosyl trichloroacetimidate donors

  • Mukta Shaw,
  • Yogesh Kumar,
  • Rima Thakur and
  • Amit Kumar

Beilstein J. Org. Chem. 2017, 13, 2385–2395, doi:10.3762/bjoc.13.236

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  • transformations [14][15][16][17]. One of the major applications of organocatalysis lies in the field of enantioselective synthesis, where organocatalysts are considered as fundamental tools in the catalysis toolbox [18][19][20][21][22]. Moreover, the reactivity and selectivity of organocatalysts can be further
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Published 09 Nov 2017

Phosphonic acid: preparation and applications

  • Charlotte M. Sevrain,
  • Mathieu Berchel,
  • Hélène Couthon and
  • Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2017, 13, 2186–2213, doi:10.3762/bjoc.13.219

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  • depolymerization of cellulose [18] and the synthesis of dihydropyrimidine derivatives [19]. The monosodium salt of phosphonic acids were also employed as organocatalysts for Michael addition [20]. The capacity of phosphonic acids to increase the solubility of organic compounds in water was employed to develop
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Published 20 Oct 2017

Mechanochemical synthesis of small organic molecules

  • Tapas Kumar Achar,
  • Anima Bose and
  • Prasenjit Mal

Beilstein J. Org. Chem. 2017, 13, 1907–1931, doi:10.3762/bjoc.13.186

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  • substituted thiourea-based organocatalysts were screened for the reaction to achieve stereoselective adducts through hydrogen bonding. Only with 2.5 mol % of thiourea-based catalyst B, α-nitrocyclohexanone and nitroalkene derivatives could undergo a Michael addition to yield up to 95% of the desired product
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Published 11 Sep 2017

Mechanochemical synthesis of thioureas, ureas and guanidines

  • Vjekoslav Štrukil

Beilstein J. Org. Chem. 2017, 13, 1828–1849, doi:10.3762/bjoc.13.178

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  • application as organocatalysts and sensors. On the other hand, the specific and unique nature of each of these functionalities render (thio)ureas and guanidines as the key constituents of pharmaceuticals and other biologically active compounds. Keywords: guanidines; mechanochemistry; solid state synthesis
  • years, molecules with incorporated (thio)urea and guanidine subunits, due to their ability to coordinate other molecules and ions via N–H hydrogen bonding, have also been considered as organocatalysts and anion sensors [7][8][9][10][11][12]. In Scheme 2, several examples of (thio)urea- and guanidine
  • -based organocatalysts are shown. Green Chemistry, which aims at turning chemical reactions into more effective and sustainable processes with high conversions of the starting materials and no byproduct formation, has emerged as a mainstream paradigm in chemical research in the past 25 years. Anastas and
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Published 01 Sep 2017

Chiral phase-transfer catalysis in the asymmetric α-heterofunctionalization of prochiral nucleophiles

  • Johannes Schörgenhumer,
  • Maximilian Tiffner and
  • Mario Waser

Beilstein J. Org. Chem. 2017, 13, 1753–1769, doi:10.3762/bjoc.13.170

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  • use of chiral metal complexes, or chiral organocatalysts have been reported, and the use of chiral PTCs became a powerful strategy herein too [44][56][57][73][74][75][76][77][78][79]. The seminal report on asymmetric phase-transfer-catalysed electrophilic α-fluorinations of prochiral carbonyl
  • alkaloid-based organocatalysts to carry out the α-trifluoromethylthiolation of β-ketoesters 1 by using the hypervalent iodine-based CF3S-transfer reagent 36 in an asymmetric fashion. Very interestingly, they realized that for indanone-based ketoesters 1 (with n = 1) simple cinchona alkaloids themselves
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Published 22 Aug 2017

Mechanochemical enzymatic resolution of N-benzylated-β3-amino esters

  • Mario Pérez-Venegas,
  • Gloria Reyes-Rangel,
  • Adrián Neri,
  • Jaime Escalante and
  • Eusebio Juaristi

Beilstein J. Org. Chem. 2017, 13, 1728–1734, doi:10.3762/bjoc.13.167

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  • . Several chiral organocatalysts and even enzymes have proved to be resistant to milling conditions, which allows for rather efficient enantioselective transformations under ball-milling conditions. The present article reports the first example of a liquid-assisted grinding (LAG) mechanochemical enzymatic
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Published 18 Aug 2017
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