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Search for "prochiral" in Full Text gives 63 result(s) in Beilstein Journal of Organic Chemistry.

Spatial arrangements of cyclodextrin host–guest complexes in solution studied by 13C NMR and molecular modelling

  • Konstantin Lebedinskiy,
  • Ivan Barvík,
  • Zdeněk Tošner,
  • Ivana Císařová,
  • Jindřich Jindřich and
  • Radim Hrdina

Beilstein J. Org. Chem. 2024, 20, 331–335, doi:10.3762/bjoc.20.33

Graphical Abstract
  • modelling and solid-state X-ray analysis, provides a detailed description of the spatial arrangement of cyclodextrin host–guest complexes in solution. The chiral cavity of the cyclodextrin molecule creates an anisotropic environment for the guest molecule resulting in a splitting of its prochiral carbon
  • signals in 13C NMR spectra. This signal split can be correlated to the distance of the guest atoms from the wall of the host cavity and to the spatial separation of binding sites preferred by pairs of prochiral carbon atoms. These measurements complement traditional solid-state analyses, which rely on the
  • anisotropy of the chiral cavity is expressed by differences in the magnetic shielding of prochiral atoms, resulting in signal splitting of the prochiral carbons of the guest molecule in 13C NMR spectra. Adamantan-2-amine hydrochloride was used as a model guest molecule containing three sets of prochiral
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Published 20 Feb 2024

Application of N-heterocyclic carbene–Cu(I) complexes as catalysts in organic synthesis: a review

  • Nosheen Beig,
  • Varsha Goyal and
  • Raj K. Bansal

Beilstein J. Org. Chem. 2023, 19, 1408–1442, doi:10.3762/bjoc.19.102

Graphical Abstract
  • compounds, including diaryl- and dialkyl ketones and prochiral ketones, respectively (Scheme 36) [50]. Riant, Leyssens and co-workers investigated the mechanism of the hydrosilylation reaction of ketones using DFT, in situ FTIR, NMR, and kinetic methods [51][52]. The catalytic characteristics of sterically
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Published 20 Sep 2023

Enolates ambushed – asymmetric tandem conjugate addition and subsequent enolate trapping with conventional and less traditional electrophiles

  • Péter Kisszékelyi and
  • Radovan Šebesta

Beilstein J. Org. Chem. 2023, 19, 593–634, doi:10.3762/bjoc.19.44

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  • desymmetrization step during which the chiral enolate attacks (Si-face) the prochiral cyclohexadienone ring via a chair-like transition state. The reaction requires an excess amount of base, resulting in the formation of a more favorable lithium enolate. Subsequent oxidation of the boronates gave the corresponding
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Published 04 May 2023

Synthetic study toward tridachiapyrone B

  • Morgan Cormier,
  • Florian Hernvann and
  • Michaël De Paolis

Beilstein J. Org. Chem. 2022, 18, 1741–1748, doi:10.3762/bjoc.18.183

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  • yield was actually noted with (PhSe)2 as electrophile, 5 being obtained in 62% yield, enabling thus an evaluation of the next desymmetrization step. An overview of the scientific literature revealed that, while the asymmetric desymmetrization of prochiral 2,5-cyclohexadienones is a rich topic of
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Published 19 Dec 2022

Synthesis of bis-spirocyclic derivatives of 3-azabicyclo[3.1.0]hexane via cyclopropene cycloadditions to the stable azomethine ylide derived from Ruhemann's purple

  • Alexander S. Filatov,
  • Olesya V. Khoroshilova,
  • Anna G. Larina,
  • Vitali M. Boitsov and
  • Alexander V. Stepakov

Beilstein J. Org. Chem. 2022, 18, 769–780, doi:10.3762/bjoc.18.77

Graphical Abstract
  • prochiral cyclopropene 2j from the less sterically hindered side. This is consistent with previous experiments in which 3-substituted-1,2-diphenylcyclopropenes were utilized as dipolarophiles. Regretfully, neither methyl 1-methylcycloprop-2-enecarboxylate (2k) [37] nor 3-methyl-1,2,3-triphenylcycloprop-1
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Published 29 Jun 2022

The asymmetric Henry reaction as synthetic tool for the preparation of the drugs linezolid and rivaroxaban

  • Martin Vrbický,
  • Karel Macek,
  • Jaroslav Pochobradský,
  • Jan Svoboda,
  • Miloš Sedlák and
  • Pavel Drabina

Beilstein J. Org. Chem. 2022, 18, 438–445, doi:10.3762/bjoc.18.46

Graphical Abstract
  • highly efficient catalysts based on copper complexes of different types of chiral ligands, 2-(pyridin-2-yl)imidazolidine-4-ones (I–III), bis-oxazolines (IV–VII), or diamine (VIII) were chosen for the study (Figure 2). Furthermore, the modification of the structure of the prochiral aldehyde intermediates
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Published 14 Apr 2022

Recent advances in the asymmetric phosphoric acid-catalyzed synthesis of axially chiral compounds

  • Alemayehu Gashaw Woldegiorgis and
  • Xufeng Lin

Beilstein J. Org. Chem. 2021, 17, 2729–2764, doi:10.3762/bjoc.17.185

Graphical Abstract
  • bulky group into the ortho-position of prochiral 3,3’-bisindoles allowed the synthesis of new members of axially chiral biaryls (3,3’-bisindole derivatives) bearing both axial and central chirality in high yields and excellent stereoselectivities. Moreover, this methodology represents a new strategy for
  • the catalytic enantioselective synthesis of axially chiral 3,3’-bisindole backbones from prochiral substrates [66]. The atroposelective synthesis of a new class of 3,3'-bisindoles 51 with axial and central chirality by dynamic kinetic resolution of 2-substituted 3,3'-bisindoles via asymmetric
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Published 15 Nov 2021

α-Ketol and α-iminol rearrangements in synthetic organic and biosynthetic reactions

  • Scott Benz and
  • Andrew S. Murkin

Beilstein J. Org. Chem. 2021, 17, 2570–2584, doi:10.3762/bjoc.17.172

Graphical Abstract
  • catalyst in the presence of a substrate possessing a prochiral migrating group or (2) stereospecifically by means of a chiral α-ketol. As an example of an enantioselective rearrangement, complexes of nickel(II) with a series of chiral 1,2-diaminopropane or pyridineoxazoline ligands were evaluated for their
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Published 15 Oct 2021

Kinetics of enzyme-catalysed desymmetrisation of prochiral substrates: product enantiomeric excess is not always constant

  • Peter J. Halling

Beilstein J. Org. Chem. 2021, 17, 873–884, doi:10.3762/bjoc.17.73

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  • Peter J. Halling WestCHEM, Dept Pure & Applied Chemistry, University of Strathclyde, Glasgow G1 1XL, Scotland, UK 10.3762/bjoc.17.73 Abstract The kinetics of enzymatic desymmetrisation were analysed for the most common kinetic mechanisms: ternary complex ordered (prochiral ketone reduction); ping
  • -pong second (ketone amination, diol esterification, desymmetrisation in the second half reaction); ping-pong first (diol ester hydrolysis) and ping-pong both (prochiral diacids). For plausible values of enzyme kinetic parameters, the product enantiomeric excess (ee) can decline substantially as the
  • study if and how the product ee declines at high conversion. Keywords: enantiomeric excess; enzyme; kinetic mechanisms; kinetic parameters; prochiral; Introduction There is great interest in using enzymatic catalysis in the synthesis of homochiral molecules. An early approach was to use
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Published 21 Apr 2021

α,γ-Dioxygenated amides via tandem Brook rearrangement/radical oxygenation reactions and their application to syntheses of γ-lactams

  • Mikhail K. Klychnikov,
  • Radek Pohl,
  • Ivana Císařová and
  • Ullrich Jahn

Beilstein J. Org. Chem. 2021, 17, 688–704, doi:10.3762/bjoc.17.58

Graphical Abstract
  • cyclized diastereomeric radicals trans-22m,n and two radicals cis-22m,n result, which differ in their orientation with respect to the racemic silyloxy group (cf. Scheme 9). The situation in the azaspiro[4,4] and azaspiro[4][5] radicals 22m,n is, however, more complex since they are prochiral, and thus
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Published 09 Mar 2021

The preparation and properties of 1,1-difluorocyclopropane derivatives

  • Kymbat S. Adekenova,
  • Peter B. Wyatt and
  • Sergazy M. Adekenov

Beilstein J. Org. Chem. 2021, 17, 245–272, doi:10.3762/bjoc.17.25

Graphical Abstract
  • enantioselective functional group interconversions on prochiral or racemic difluorocyclopropane and difluorocyclopropene derivatives have provided important ways of obtaining enantiomerically pure cyclopropanes. The key reactions in this context are the enzyme-catalyzed formation and hydrolysis of esters and the
  • hydrogenation of difluorocyclopropenes [73][79]. Enzymatic hydrolysis or esterification: The first example of the enzymatic resolution of gem-difluorocyclopropanes was reported by Itoh et al. [80]. The prochiral diacetate of cis-1,2-bis-(hydroxymethyl)-3,3-difluorocyclopropane was converted into the
  • [81]. The authors obtained the chiral monoacetate intermediates (R)-78 and (S)-80 by lipase-catalyzed methods. The lipase-catalyzed asymmetric transesterification of prochiral diol 77 and the deacetylation of the prochiral diacetate 79 resulted in the formation of the (R)-monoacetate (R)-78 and (S
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Published 26 Jan 2021

Insight into functionalized-macrocycles-guided supramolecular photocatalysis

  • Minzan Zuo,
  • Krishnasamy Velmurugan,
  • Kaiya Wang,
  • Xueqi Tian and
  • Xiao-Yu Hu

Beilstein J. Org. Chem. 2021, 17, 139–155, doi:10.3762/bjoc.17.15

Graphical Abstract
  • photochemical reactions, including photoisomerization, photocyclodimerization, and H2 evolution [7][23]. Chirality induction in a prochiral guest via photochemical reactions is a delightful approach. This can not only transfer the chirality of the host cavity to the molecular photoproduct via excited-state
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Published 18 Jan 2021

Ring-closing metathesis of prochiral oxaenediynes to racemic 4-alkenyl-2-alkynyl-3,6-dihydro-2H-pyrans

  • Viola Kolaříková,
  • Markéta Rybáčková,
  • Martin Svoboda and
  • Jaroslav Kvíčala

Beilstein J. Org. Chem. 2020, 16, 2757–2768, doi:10.3762/bjoc.16.226

Graphical Abstract
  • ., Flemingovo nám. 2, 166 10 Prague 6, Czech Republic 10.3762/bjoc.16.226 Abstract The prochiral 4-(allyloxy)hepta-1,6-diynes, optionally modified in the positions 1 and 7 with an alkyl or ester group, undergo a chemoselective ring-closing enyne metathesis yielding racemic 4-alkenyl-2-alkynyl-3,6-dihydro-2H
  • for other catalytic reactions, e.g., for the Pauson–Khand reaction [14]. In the enantioselective RCM, prochiral trienes have been most often employed, leading to chiral cycloalkenes. The Schrock molybdenum precatalysts [15][16][17] proved to be more effective than the Grubbs or Collins ruthenium
  • significantly more demanding strategy uses prochiral substrates and chiral metathesis precatalysts. Despite many examples of enantioselective RCM, only two examples of an enantioselective RCEYM have been reported (both featuring a dienyne substrate and a Schrock complex) [21][30], no enantioselective enediyne
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Published 13 Nov 2020

Water-soluble host–guest complexes between fullerenes and a sugar-functionalized tribenzotriquinacene assembling to microspheres

  • Si-Yuan Liu,
  • Xin-Rui Wang,
  • Man-Ping Li,
  • Wen-Rong Xu and
  • Dietmar Kuck

Beilstein J. Org. Chem. 2020, 16, 2551–2561, doi:10.3762/bjoc.16.207

Graphical Abstract
  • is clearly a consequence of the prochiral nature of the TBTQ core. We also note that such splitting phenomenon was reported for neither six-fold sugar-functionalized cyclotriveratrylenes [41], which are directly comparable to TBTQ-(OAcG)6, nor for six-fold sugar-functionalized triptycene [42], and
  • of three magnetically equivalent tentacles at the rigid, prochiral TBTQ skeleton. The mass spectrometric characterization of TBTQ-(OAcG)6 turned out to be quite difficult. The MALDI-(+) mass spectrum (see Figure S10 and Table S1 in Supporting Information File 1), recorded with α-cyano-4
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Published 14 Oct 2020

Hierarchically assembled helicates as reaction platform – from stoichiometric Diels–Alder reactions to enamine catalysis

  • David Van Craen,
  • Jenny Begall,
  • Johannes Großkurth,
  • Leonard Himmel,
  • Oliver Linnenberg,
  • Elisabeth Isaak and
  • Markus Albrecht

Beilstein J. Org. Chem. 2020, 16, 2338–2345, doi:10.3762/bjoc.16.195

Graphical Abstract
  • processes based on the principle to use self-assembled coordination platforms (or as in the present case mixtures thereof) to control stereoselective C–C bond-forming reactions. Stereoinduction usually relies on spatial proximity of the prochiral carbon atoms and a chiral information of, e.g., a chiral
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Published 24 Sep 2020

NHC-catalyzed enantioselective synthesis of β-trifluoromethyl-β-hydroxyamides

  • Alyn T. Davies,
  • Mark D. Greenhalgh,
  • Alexandra M. Z. Slawin and
  • Andrew D. Smith

Beilstein J. Org. Chem. 2020, 16, 1572–1578, doi:10.3762/bjoc.16.129

Graphical Abstract
  • stereogenic trifluoromethyl centers is through enantioselective addition of enolates or their equivalents to prochiral trifluoromethyl ketones (Figure 1A). Within this area, a common catalytic approach has utilized aliphatic ketones as enolate equivalents using prolinamide, cinchona, or hybrid catalysts that
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Published 30 Jun 2020

A review of asymmetric synthetic organic electrochemistry and electrocatalysis: concepts, applications, recent developments and future directions

  • Munmun Ghosh,
  • Valmik S. Shinde and
  • Magnus Rueping

Beilstein J. Org. Chem. 2019, 15, 2710–2746, doi:10.3762/bjoc.15.264

Graphical Abstract
  • of a poly-ʟ-valine 6 coated graphite cathode for asymmetric electrochemical reductions in two consecutive reports. In the first communication, they carried out the asymmetric reduction of prochiral activated olefins 5 and 8, affording 7 and 9 with optical yields of 25% and 43%, respectively (Scheme 3
  • ) [23]. In the second report, the same electrode was applied for the asymmetric reduction of prochiral carbonyl compounds 10a and 12a, oximes 14 and gem-dibromo compounds 16 (Scheme 4). Among all of these the highest optical yield (16.6%) was obtained in the reduction of gem-dibromide substrates 16 to
  • catalyze the enantioselective hydrogenation of prochiral ketones 18. The prochiral ketones such as acetophenone, 1-tetralone and 1-indanone were reduced to their corresponding alcohols 20a, 20b and 20c, respectively, with moderate optical yields, with formation of (S) as major enantiomer (Scheme 5). After
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Published 13 Nov 2019

Chiral terpene auxiliaries V: Synthesis of new chiral γ-hydroxyphosphine oxides derived from α-pinene

  • Anna Kmieciak and
  • Marek P. Krzemiński

Beilstein J. Org. Chem. 2019, 15, 2493–2499, doi:10.3762/bjoc.15.242

Graphical Abstract
  • ligands that were obtained from readily available natural (1S)-β-pinene and (1S)-α-pinene [18]. We applied these ligands for the formation of the ruthenium complexes, which were successfully used as catalysts in asymmetric transfer hydrogenation of prochiral ketones. In continuation of our studies on the
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Published 22 Oct 2019

Self-assembled coordination thioether silver(I) macrocyclic complexes for homogeneous catalysis

  • Zhen Cao,
  • Aline Lacoudre,
  • Cybille Rossy and
  • Brigitte Bibal

Beilstein J. Org. Chem. 2019, 15, 2465–2472, doi:10.3762/bjoc.15.239

Graphical Abstract
  • . These silver(I) complexes adopted similar structures in solution and in the solid state. As each sulfur atom in the ligand is prochiral, macrocycles L2M2 were obtained as mixtures of diastereoisomers, depending on the configurations of the sulfur atoms coordinated to silver cations. The X-ray structures
  • ; homogeneous catalysis; prochiral; silver complex; thioether ligand; Introduction Since the early advances in the late eighties [1][2][3][4][5][6][7][8][9][10], silver(I) catalysis has been widely exploited based on the versatile redox and soft Lewis acid properties of this coinage metal cation. Silver
  • prochiral sulfur atom of the ligand becomes asymmetric by coordination to silver(I). In absence of any chiral source, the complexes were obtained either as nonchiral coordination products with a center or an axis of symmetry (1a and 1c, with (R,S)–1 ligands) or as a racemic mixture (1d, with (R,R)–1 or (S,S
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Published 17 Oct 2019

Asymmetric synthesis of a high added value chiral amine using immobilized ω-transaminases

  • Antonella Petri,
  • Valeria Colonna and
  • Oreste Piccolo

Beilstein J. Org. Chem. 2019, 15, 60–66, doi:10.3762/bjoc.15.6

Graphical Abstract
  • prochiral precursor 1-Boc-3-piperidone using immobilized ω-transaminases (TAs-IMB), isopropylamine as amine donor and pyridoxal-5’-phosphate (PLP) as cofactor is described. Compared to other methods, the present approach affords the target compound in just one step with high yield and high enantiomeric
  • by using resolution of racemic mixtures, preparation from chiral precursors or asymmetric synthesis from prochiral compounds [20][21][22]. In contrast, only few examples have been published on the synthesis of this molecule through biotransformations [23][24]. In these procedures TAs are used in
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Published 07 Jan 2019

Ruthenium-based olefin metathesis catalysts with monodentate unsymmetrical NHC ligands

  • Veronica Paradiso,
  • Chiara Costabile and
  • Fabia Grisi

Beilstein J. Org. Chem. 2018, 14, 3122–3149, doi:10.3762/bjoc.14.292

Graphical Abstract
  •  31). The catalytic performances of 164 were tested in the asymmetric ring-closing metathesis (ARCM) of prochiral trienes 166, 168 and 170 (Scheme 15, Table 6) [52][54] achieving enantiomeric excesses (ee) that were generally lower with respect to those obtained with the C2-symmetrical analogue 165
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Published 28 Dec 2018

Stereoselective total synthesis and structural revision of the diacetylenic diol natural products strongylodiols H and I

  • Pamarthi Gangadhar,
  • Sayini Ramakrishna,
  • Ponneri Venkateswarlu and
  • Pabbaraja Srihari

Beilstein J. Org. Chem. 2018, 14, 2313–2320, doi:10.3762/bjoc.14.206

Graphical Abstract
  • 25 and 25a was oxidized under Dess–Martin conditions to give the prochiral ene–yne–one 17 in 87% yield. The ketone 17 was then subjected to a stereoselective asymmetric reduction [23][29][30][31] in the presence of (S)-CBS as the catalyst to yield the chiral propargylic alcohol 25 with 92% ee (Scheme
  • natural product as 9a which is the enantiomer of the proposed structure 9 (Figure 3). Further, to reconfirm the structural revision, we synthesized the other enantiomer of strongylodiol H. Towards this we proceeded for the stereoselective reduction of prochiral ketone 17 with (R)-CBS as the catalyst
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Published 04 Sep 2018

Calix[6]arene-based atropoisomeric pseudo[2]rotaxanes

  • Carmine Gaeta,
  • Carmen Talotta and
  • Placido Neri

Beilstein J. Org. Chem. 2018, 14, 2112–2124, doi:10.3762/bjoc.14.186

Graphical Abstract
  • threading a tertiary ammonium axles in a directional (non-flat) calixarene-wheel (II and II*, Figure 1) [17]. In this case the chirality is created by the directionality of the calixarene wheel in a cone conformation, which differentiates the two alkyl chains around the prochiral ammonium center. In 2010
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Published 14 Aug 2018

D-Fructose-based spiro-fused PHOX ligands: synthesis and application in enantioselective allylic alkylation

  • Michael R. Imrich,
  • Jochen Kraft,
  • Cäcilia Maichle-Mössmer and
  • Thomas Ziegler

Beilstein J. Org. Chem. 2018, 14, 2082–2089, doi:10.3762/bjoc.14.182

Graphical Abstract
  • enantioselectivity [1][2]. Probably the most effective approach in stereoselective synthesis is enantioselective catalysis, because cheap prochiral starting materials can be converted into chiral enantiopure products and no undesirable side products are formed [3][4]. Therefore, the development of new ligands is
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Published 08 Aug 2018

Recent advances in hypervalent iodine(III)-catalyzed functionalization of alkenes

  • Xiang Li,
  • Pinhong Chen and
  • Guosheng Liu

Beilstein J. Org. Chem. 2018, 14, 1813–1825, doi:10.3762/bjoc.14.154

Graphical Abstract
  • environment at the iodine center. Mechanistically, the iodine(III) 16 is activated by triflic acid generating a free coordination site at the iodine(III) center [54]. The coordination of the alkene to the activated iodine(III) center generates the required prochiral face differentiation and the nucleophilic
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Published 18 Jul 2018
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