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Search for "organocatalysis" in Full Text gives 193 result(s) in Beilstein Journal of Organic Chemistry.

Metal-mediated aminocatalysis provides mild conditions: Enantioselective Michael addition mediated by primary amino catalysts and alkali-metal ions

  • Matthias Leven,
  • Jörg M. Neudörfl and
  • Bernd Goldfuss

Beilstein J. Org. Chem. 2013, 9, 155–165, doi:10.3762/bjoc.9.18

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  • catalysis provides an effective alternative to conventional primary amino catalysis were strong acid additives are essential components. Keywords: alkali metals; aminocatalysis; DFT-calculations; Lewis acids; Michael addition; Introduction Organocatalysis based on primary or secondary amines enables a
  • famous examples are Mac Millan’s secondary-amine-based catalysts [6] or 9-amino-9-deoxy-epihydroquinine salts used by Jørgensen et al. [7][8]. Another growing field of catalysis is metal-promoted organocatalysis, which is closely related to tandem reactions of metal- and organocatalysis [9][10][11][12
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Published 23 Jan 2013

Mechanochemistry assisted asymmetric organocatalysis: A sustainable approach

  • Pankaj Chauhan and
  • Swapandeep Singh Chimni

Beilstein J. Org. Chem. 2012, 8, 2132–2141, doi:10.3762/bjoc.8.240

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  • methods for the development of environmentally benign chemical transformations. Recently, the use of these mechanochemical techniques in asymmetric organocatalysis has increased. This review highlights the progress in asymmetric organocatalytic reactions assisted by mechanochemical techniques. Keywords
  • : ball-milling; enantioselective synthesis; mechanochemistry; organocatalysis; solvent-free; Introduction Green chemistry involves innovation in chemical research and engineering that encourages the design of processes to minimize the use and production of hazardous materials and also reduce the use of
  • amplified in recent times. In this regard, catalytic asymmetric synthesis involving the use of chiral organocatalysts has emerged as a powerful tool from the infancy to the maturity of asymmetric organocatalysis [13][14][15][16][17][18][19][20][21][22][23][24][25][26]. The use of organocatalysts for
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Published 06 Dec 2012

Design and synthesis of a photoswitchable guanidine catalyst

  • Philipp Viehmann and
  • Stefan Hecht

Beilstein J. Org. Chem. 2012, 8, 1825–1830, doi:10.3762/bjoc.8.209

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  • rac-lactide in order to explain the findings. Keywords: azobenzenes; guanidines; molecular switches; organocatalysis; photochromism; ring opening polymerization; Introduction The macroscopic properties of a given polymer, e.g., the glass-transition temperature, morphology, density and tensile
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Published 24 Oct 2012

Asymmetric Brønsted acid-catalyzed aza-Diels–Alder reaction of cyclic C-acylimines with cyclopentadiene

  • Magnus Rueping and
  • Sadiya Raja

Beilstein J. Org. Chem. 2012, 8, 1819–1824, doi:10.3762/bjoc.8.208

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  • optically active aza-tetracycles in good yields with high diastereo- and enantioselectivities under mild reaction conditions. Keywords: BINOL phosphate; [4 + 2] cycloaddition; Diels–Alder reaction; organocatalysis; Introduction The enantioselective aza-Diels–Alder reaction is an important method for the
  • compounds. Acknowledgements Financial support by the DFG priority programme Organocatalysis is gratefully acknowledged.
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Published 23 Oct 2012

Automated three-component synthesis of a library of γ-lactams

  • Erik Fenster,
  • David Hill,
  • Oliver Reiser and
  • Jeffrey Aubé

Beilstein J. Org. Chem. 2012, 8, 1804–1813, doi:10.3762/bjoc.8.206

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  • ; maleimide; organocatalysis; parallel synthesis; reductive amination; Introduction In recent years, the rapid access to structurally diverse and complex small molecules has grown in importance within the context of high-throughput screening of biologically relevant targets. The need for such compounds, both
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Published 19 Oct 2012

Imidazolinium and amidinium salts as Lewis acid organocatalysts

  • Oksana Sereda,
  • Nicole Clemens,
  • Tatjana Heckel and
  • René Wilhelm

Beilstein J. Org. Chem. 2012, 8, 1798–1803, doi:10.3762/bjoc.8.205

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  • desulfurization of the products containing a thiol or thiocarbonyl group. Keywords: Diels–Alder; ionic liquids; organocatalysis; soft Lewis acids; thiiranes; thioesters; Introduction Salts with melting points below 100 °C are known as ionic liquids and are often used as novel solvents for reactions and
  • the C(2) position as catalysts for the aza-Diels–Alder reaction [11][12]. These catalysts do not activate the substrate through hydrogen bonding, but instead, like other carbon-cation based catalysts, through their positive center [8][9][10][13][14][15], and belong also to the field of organocatalysis
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Published 18 Oct 2012

Asymmetric desymmetrization of meso-diols by C2-symmetric chiral 4-pyrrolidinopyridines

  • Hartmut Schedel,
  • Keizo Kan,
  • Yoshihiro Ueda,
  • Kenji Mishiro,
  • Keisuke Yoshida,
  • Takumi Furuta and
  • Takeo Kawabata

Beilstein J. Org. Chem. 2012, 8, 1778–1787, doi:10.3762/bjoc.8.203

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  • pyrrolidinopyridine framework as a catalytic site. Some of these organocatalysts effectively promoted asymmetric desymmetrization of meso-diols via enantioselective acylation. Keywords: acylation; desymmetrization; hydrogen bond; meso-diol; nucleophilic catalyst; organocatalysis; Introduction Since the pioneering
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Published 17 Oct 2012

Synthesis and ring openings of cinnamate-derived N-unfunctionalised aziridines

  • Alan Armstrong and
  • Alexandra Ferguson

Beilstein J. Org. Chem. 2012, 8, 1747–1752, doi:10.3762/bjoc.8.199

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  • -diphenylphosphinyl hydroxylamine. The resulting N-unfunctionalised aziridines are shown to be versatile synthetic building blocks that undergo highly selective ring-opening reactions with a wide range of nucleophiles. Keywords: amino acids; aziridination; organocatalysis; ring opening; stereoselectivity
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Published 12 Oct 2012

Organocatalytic cascade aza-Michael/hemiacetal reaction between disubstituted hydrazines and α,β-unsaturated aldehydes: Highly diastereo- and enantioselective synthesis of pyrazolidine derivatives

  • Zhi-Cong Geng,
  • Jian Chen,
  • Ning Li,
  • Xiao-Fei Huang,
  • Yong Zhang,
  • Ya-Wen Zhang and
  • Xing-Wang Wang

Beilstein J. Org. Chem. 2012, 8, 1710–1720, doi:10.3762/bjoc.8.195

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  • good results (up to 86% yield, >10/1 regioselectivity, >20:1 dr, 99% ee) in the presence of (S)-diphenylprolinol trimethylsilyl ether catalyst. Keywords: aza-Michael; domino; hydrazine; organocatalysis; pyrazolidine; Introduction Pyrazolidines are privileged and valuable heterocyclic compounds, which
  • synthesis of pyrazolidine derivatives by Wolfe et al. [33]. In the past decade, the research area of organocatalysis has grown rapidly and become a third brand of catalysis besides the well-established biocatalysis and metal catalysis [34][35][36][37][38][39][40][41][42][43][44]. Particularly
  • stereoselective cascade reaction for the synthesis of the pyrazolidine compounds through organocatalysis. In this paper, we present a convenient access to racemic and enantioenriched 5-hydroxypyrazolidines through a domino aza-Michael/hemiacetal organocatalytic sequence of disubstituted hydrazines to α,β
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Published 09 Oct 2012

Enantioselective total synthesis of (R)-(−)-complanine

  • Krystal A. D. Kamanos and
  • Jonathan M. Withey

Beilstein J. Org. Chem. 2012, 8, 1695–1699, doi:10.3762/bjoc.8.192

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  • ; organocatalysis; Introduction The marine fireworm Eurythoe complanata resides in the shallow water and sands of temperate and sub-tropical regions. Its small setae cause skin inflammation upon contact, the causative agent having been identified as complanine. This novel amphipathic substance was first isolated
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Published 04 Oct 2012

Organocatalytic tandem Michael addition reactions: A powerful access to the enantioselective synthesis of functionalized chromenes, thiochromenes and 1,2-dihydroquinolines

  • Chittaranjan Bhanja,
  • Satyaban Jena,
  • Sabita Nayak and
  • Seetaram Mohapatra

Beilstein J. Org. Chem. 2012, 8, 1668–1694, doi:10.3762/bjoc.8.191

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  • organocatalysis has become a field of central importance within asymmetric chemical synthesis and appears to be efficient approach toward the construction of complex chiral molecules from simple achiral materials in one-pot transformations under mild conditions with high stereocontrol. This review addresses the
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Published 04 Oct 2012

Cyclization of ortho-hydroxycinnamates to coumarins under mild conditions: A nucleophilic organocatalysis approach

  • Florian Boeck,
  • Max Blazejak,
  • Markus R. Anneser and
  • Lukas Hintermann

Beilstein J. Org. Chem. 2012, 8, 1630–1636, doi:10.3762/bjoc.8.186

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  • -hydroxycinnamates, followed by the phosphane catalyzed cyclization. Keywords: catalysis; coumarins; heterocycles; mechanisms; organocatalysis; phosphanes; Introduction Coumarins are important structural motifs in natural products and bioactive compounds, in which they exhibit broad biological activity, e.g., as
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Published 26 Sep 2012

N-Heterocyclic carbene-catalyzed direct cross-aza-benzoin reaction: Efficient synthesis of α-amino-β-keto esters

  • Takuya Uno,
  • Yusuke Kobayashi and
  • Yoshiji Takemoto

Beilstein J. Org. Chem. 2012, 8, 1499–1504, doi:10.3762/bjoc.8.169

Graphical Abstract
  • -amino-β-keto esters; cross-aza-benzoin; α-imino ester; N-heterocyclic carbenes; organocatalysis; umpolung reactions; Introduction α-Amino-β-keto ester derivatives are one of the fundamental structural subunits in natural products such as miuraenamides [1], and important building blocks for the
  • Supporting Information File 334: Experimental details and characterization of the synthesized compounds. Acknowledgements This work was supported in part by a Grant-in-Aid for Scientific Research on Innovative Areas “Advanced Molecular Transformations by Organocatalysis” and “Targeted Proteins Research
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Published 10 Sep 2012

Synthesis and evaluation of new guanidine-thiourea organocatalyst for the nitro-Michael reaction: Theoretical studies on mechanism and enantioselectivity

  • Tatyana E. Shubina,
  • Matthias Freund,
  • Sebastian Schenker,
  • Timothy Clark and
  • Svetlana B. Tsogoeva

Beilstein J. Org. Chem. 2012, 8, 1485–1498, doi:10.3762/bjoc.8.168

Graphical Abstract
  • . Extensive DFT calculations, including solvent effects and dispersion corrections, as well as ab initio calculations provide a plausible description of the reaction mechanism. Keywords: bifunctional organocatalyst; DFT calculations; guanidine-thiourea; Michael addition; organocatalysis; transition states
  • archive entries. Supporting Information File 434: Detailed information about the DFT calculations Acknowledgements The authors gratefully acknowledge generous financial support from the Deutsche Forschungsgemeinschaft (SPP 1179 “Organocatalysis”) and the generous amount of computational time from HLRBII
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Published 07 Sep 2012

A quantitative approach to nucleophilic organocatalysis

  • Herbert Mayr,
  • Sami Lakhdar,
  • Biplab Maji and
  • Armin R. Ofial

Beilstein J. Org. Chem. 2012, 8, 1458–1478, doi:10.3762/bjoc.8.166

Graphical Abstract
  • ; kinetics; NHC activation; organocatalysis; structure reactivity relationships; Review Introduction The most comprehensive nucleophilicity and electrophilicity scales presently available, are based on Equation 1, in which electrophiles are characterized by one solvent-independent parameter E, and
  • aliphatic substitutions [21][22]. In this essay, we will illustrate applications of Equation 1 in nucleophilic organocatalysis. Iminium activated reactions A key step of the commonly accepted catalytic cycle for iminium activated reactions (Figure 2) is the attack of a nucleophile 4 on the intermediate
  • 1179 Organokatalyse / Priority Program 1179 Organocatalysis 2004–2010 and SFB 749) for financial support.
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Published 05 Sep 2012

Organocatalytic asymmetric addition of malonates to unsaturated 1,4-diketones

  • Sergei Žari,
  • Tiiu Kailas,
  • Marina Kudrjashova,
  • Mario Öeren,
  • Ivar Järving,
  • Toomas Tamm,
  • Margus Lopp and
  • Tõnis Kanger

Beilstein J. Org. Chem. 2012, 8, 1452–1457, doi:10.3762/bjoc.8.165

Graphical Abstract
  • calculated VCD spectra of the reaction product 3a. Keywords: Michael addition; non-covalent catalysis; organocatalysis; squaramide; thiourea; Introduction The asymmetric 1,4-conjugated addition (Michael reaction) of C-nucleophiles to enones is a powerful tool for obtaining a significant variety of
  • enantiomer. From the synthetic point of view, the conjugate addition of the nucleophile is, at the same time, a formal umpolung reaction with respect to the other carbonyl group (Figure 1). Results and Discussion Catalyst screening As a part of our ongoing studies in organocatalysis [16][17][18][19] we
  • ), and the EU European Regional Development Fund (3.2.0101.08-0017) for financial support and COST Action CM0905 (ORCA, Organocatalysis).
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Published 04 Sep 2012

Synthesis of chiral sulfoximine-based thioureas and their application in asymmetric organocatalysis

  • Marcus Frings,
  • Isabelle Thomé and
  • Carsten Bolm

Beilstein J. Org. Chem. 2012, 8, 1443–1451, doi:10.3762/bjoc.8.164

Graphical Abstract
  • catalysts in high overall yields without affecting the stereohomogeneity of the sulfur-containing core fragment. Keywords: anhydride opening; catalytic asymmetric Biginelli reaction; organocatalysis; sulfoximines; thioureas; Introduction Since their discovery in the middle of the last century
  • hydrogenations and carbon–carbon bond formations [34][35][36]. During the past decade, asymmetric organocatalysis had a tremendous impact on synthetic organic chemistry [37][38][39][40][41]. Yet, this field of research continues to grow, and the quest for new organic molecules which efficiently catalyze
  • (-like) catalysts with S-stereogenic sulfonimidoyl substituents are unknown. Herein, we present our first results concerning synthetic approaches towards such molecules and describe preliminary studies of two applications in asymmetric organocatalysis. Results and Discussion Our investigations began with
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Published 03 Sep 2012

Cation affinity numbers of Lewis bases

  • Christoph Lindner,
  • Raman Tandon,
  • Boris Maryasin,
  • Evgeny Larionov and
  • Hendrik Zipse

Beilstein J. Org. Chem. 2012, 8, 1406–1442, doi:10.3762/bjoc.8.163

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  • substrate model for acyl-transfer reactions. Affinities towards these cationic electrophiles are complemented by data for Lewis-base addition to Michael acceptors as prototypical neutral electrophiles. Keywords: ab initio; cation affinity; Lewis basicity; organocatalysis; proton affinity; Introduction
  • group of phosphanes are presented in Table 6 in which most of the phosphanes are interesting for organocatalysis. Again, all MCA values are calculated for reaction at the phosphorus atom if not mentioned otherwise. In order to discuss inductive and mesomeric electron-donating effects the tri-para
  • /mol. Triarylphosphanes can be of interest for organocatalysis if at least one substituent in ortho-position of a phenyl group enables hydrogen bonds to the substrate as is, for example, the case in phosphanes 260, 287, and 293. These latter three compounds differ only in the position of the
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Published 31 Aug 2012

Highly enantioselective access to cannabinoid-type tricyles by organocatalytic Diels–Alder reactions

  • Stefan Bräse,
  • Nicole Volz,
  • Franziska Gläser and
  • Martin Nieger

Beilstein J. Org. Chem. 2012, 8, 1385–1392, doi:10.3762/bjoc.8.160

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  • synthesis. Keywords: cannabinoids; Diels–Alder reaction; natural product synthesis; organocatalysis; Introduction The Diels–Alder reaction is one of the most important processes for carbon–carbon-bond formation in organic chemistry [1][2]. Especially in the synthesis of natural products it is a widely
  • fine chemicals, were either transition-metal complexes or enzymes. In the past few years, however, organocatalysis has emerged as an alternative approach for the catalytic production of enantiomerically pure organic compounds [15][16]. These organocatalysts have several important advantages. They are
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Published 28 Aug 2012

Organocatalytic C–H activation reactions

  • Subhas Chandra Pan

Beilstein J. Org. Chem. 2012, 8, 1374–1384, doi:10.3762/bjoc.8.159

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  • non-asymmetric and asymmetric C–H activation reactions mediated by organocatalysts are discussed in this review. Keywords: asymmetric; C–H activation; non-asymmetric; organocatalysis; organocatalytic; Introduction C–H activation reactions have recently been found to be a powerful method for the
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Published 27 Aug 2012

Organocatalytic asymmetric Michael addition of unprotected 3-substituted oxindoles to 1,4-naphthoquinone

  • Jin-Sheng Yu,
  • Feng Zhou,
  • Yun-Lin Liu and
  • Jian Zhou

Beilstein J. Org. Chem. 2012, 8, 1360–1365, doi:10.3762/bjoc.8.157

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  • catalytic synthesis of which was unprecedented. Keywords: 3,3-disubstituted oxindoles; Michael addition; organocatalysis; quaternary stereogenic center; unprotected 3-substituted oxindoles; Introduction The catalytic asymmetric synthesis of 3,3-disubstituted oxindoles has recently received great attention
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Published 23 Aug 2012

Organocatalysis

  • Benjamin List

Beilstein J. Org. Chem. 2012, 8, 1358–1359, doi:10.3762/bjoc.8.156

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  • Benjamin List Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, D-45470 Mülheim an der Ruhr, Germany 10.3762/bjoc.8.156 Keywords: organocatalysis; During the past 12 years or so, hardly any other field has impacted the art and science of chemical synthesis more profoundly than
  • organocatalysis. The growth, both in academic research and in industrial use, has been breathtaking. Judging by the development of its impact factor, the Beilstein Journal of Organic Chemistry is currently attempting to achieve the same impact within chemistry publishing. A Beilstein Thematic Series on
  • Organocatalysis therefore appeared to be quite logical. A brilliant opportunity arose in the context of a priority program sponsored by the Deutsche Forschungsgemeinschaft (DFG), which has in the meanwhile supported the organocatalysis research of over thirty groups in Germany between 2004 and 2010. The series in
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Published 23 Aug 2012

Asymmetric one-pot sequential Friedel–Crafts-type alkylation and α-oxyamination catalyzed by a peptide and an enzyme

  • Kengo Akagawa,
  • Ryota Umezawa and
  • Kazuaki Kudo

Beilstein J. Org. Chem. 2012, 8, 1333–1337, doi:10.3762/bjoc.8.152

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  • -functionalized indole or pyrrole derivatives in a highly enantioselective manner. Keywords: Friedel–Crafts-type alkylation; laccase; one-pot reaction; organocatalysis; α-oxyamination; resin-supported peptide catalyst; Findings Indole derivatives represent a class of biologically active compounds [1][2][3], and
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Published 17 Aug 2012

Asymmetric organocatalytic decarboxylative Mannich reaction using β-keto acids: A new protocol for the synthesis of chiral β-amino ketones

  • Chunhui Jiang,
  • Fangrui Zhong and
  • Yixin Lu

Beilstein J. Org. Chem. 2012, 8, 1279–1283, doi:10.3762/bjoc.8.144

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  • , catalyzed by cinchonine-derived bifunctional thiourea catalyst has been described. The desired β-amino ketones were obtained in excellent yields and with moderate to good enantioselectivities. Keywords: decarboxylative addition; β-keto acid; Mannich reaction; organocatalysis; Introduction Chiral β-amino
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Published 13 Aug 2012

Organocatalytic asymmetric allylic amination of Morita–Baylis–Hillman carbonates of isatins

  • Hang Zhang,
  • Shan-Jun Zhang,
  • Qing-Qing Zhou,
  • Lin Dong and
  • Ying-Chun Chen

Beilstein J. Org. Chem. 2012, 8, 1241–1245, doi:10.3762/bjoc.8.139

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  • yields (up to 97%). Keywords: allylic amination; asymmetric organocatalysis; Morita–Baylis–Hillman carbonates; 2-oxindoles; quaternary chiral center; Introduction Chiral 3-amino-2-oxindoles are versatile and useful units for the preparation of natural products and drug candidates, such as the
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Published 06 Aug 2012
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