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Search for "leaving group" in Full Text gives 251 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.

Interactions of cyclodextrins and their derivatives with toxic organophosphorus compounds

  • Sophie Letort,
  • Sébastien Balieu,
  • William Erb,
  • Géraldine Gouhier and
  • François Estour

Beilstein J. Org. Chem. 2016, 12, 204–228, doi:10.3762/bjoc.12.23

Graphical Abstract
  • organophosphorus (NOPs) share a typical structure with a pentavalent phosphorus atom linked to a leaving group (LG), two substituents (R1 and R2) and an oxygen or a sulfur atom (Figure 1), explaining the wide structural diversity of organophosphates. They can be classified into three categories depending on the
  • nature of the leaving group. The first one includes the least toxic compounds used as pesticides; the second one corresponds to the G agents developed as chemical warfare agents and the third one to the dreadful V agents group (Figure 2). Due to their use in agriculture, organophosphate accidental or
  • the P(R)-isomers into the CD cavity is followed by the formation of a hydrogen bond between a C-3 hydroxy and the phosphoryl oxygen atom of soman. Then a C-2 ionized hydroxy function attacks the phosphorus atom to form a covalent bond with the release of the leaving group (fluoride ion). The different
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Published 05 Feb 2016

Synthesis and nucleophilic aromatic substitution of 3-fluoro-5-nitro-1-(pentafluorosulfanyl)benzene

  • Javier Ajenjo,
  • Martin Greenhall,
  • Camillo Zarantonello and
  • Petr Beier

Beilstein J. Org. Chem. 2016, 12, 192–197, doi:10.3762/bjoc.12.21

Graphical Abstract
  • the use of liquid ammonia as a co-solvent (Table 2, entry 5). For direct amination 1,1,1-trimethylhydrazinium iodide was used, which upon deprotonation with strong base provided the nitrogen nucleophile containing the leaving group (Me3N) (Table 2, entry 6). High regioselectivities were observed in
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Published 03 Feb 2016

Synthesis of Xenia diterpenoids and related metabolites isolated from marine organisms

  • Tatjana Huber,
  • Lara Weisheit and
  • Thomas Magauer

Beilstein J. Org. Chem. 2015, 11, 2521–2539, doi:10.3762/bjoc.11.273

Graphical Abstract
  • cyclononenes in a stereospecific manner [27]. The relative configuration of the leaving group (LG = OTs, OMs, Hal, NR3+) and the adjacent substituent determine the E/Z-geometry of the olefin. A cis-geometry leads to the formation of the E-configured double bond. In general, the Grob fragmentation is the most
  • conditions [48] and an ensuing desilylation furnished a diol. In order to introduce a leaving group for the following key step, the secondary hydroxy group was tosylated to afford 79. Once again, a stereospecific Grob fragmentation of tosylate 79 served as the key step for the synthesis of the
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Published 10 Dec 2015

Copper-catalysed asymmetric allylic alkylation of alkylzirconocenes to racemic 3,6-dihydro-2H-pyrans

  • Emeline Rideau and
  • Stephen P. Fletcher

Beilstein J. Org. Chem. 2015, 11, 2435–2443, doi:10.3762/bjoc.11.264

Graphical Abstract
  • is formed in a completely non-selective pathway. In the case of allyl phosphate 2d, the system appears to lack reactivity and the reaction quickly dies, so that 10 (Figure 3) is formed with poor conversion, and we speculate that the phosphate leaving group inhibits the catalyst which would explain
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Published 03 Dec 2015

Coupling of α,α-difluoro-substituted organozinc reagents with 1-bromoalkynes

  • Artem A. Zemtsov,
  • Alexander D. Volodin,
  • Vitalij V. Levin,
  • Marina I. Struchkova and
  • Alexander D. Dilman

Beilstein J. Org. Chem. 2015, 11, 2145–2149, doi:10.3762/bjoc.11.231

Graphical Abstract
  • nitrostryrenes (with the NO2 serving as a leaving group) [20], were employed. Herein, we report that 1-bromoalkynes, which are known to be involved in reactions with various organometallic compounds [22][23][24][25][26][27], can be used as suitable coupling partners for difluorinated organozinc compounds 2. This
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Published 10 Nov 2015

A comprehensive study of olefin metathesis catalyzed by Ru-based catalysts

  • Albert Poater and
  • Luigi Cavallo

Beilstein J. Org. Chem. 2015, 11, 1767–1780, doi:10.3762/bjoc.11.192

Graphical Abstract
  • pyridine groups, but the function of both chemical groups is the same. The release of a pyridine or phosphine group generates a 14-electron (14e) species, which binds to an olefin, coordinated cis to the alkylidene. The exchange of the leaving group by an olefin is found to be mainly dissociative [4][27
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Published 29 Sep 2015

Dicarboxylic esters: Useful tools for the biocatalyzed synthesis of hybrid compounds and polymers

  • Ivan Bassanini,
  • Karl Hult and
  • Sergio Riva

Beilstein J. Org. Chem. 2015, 11, 1583–1595, doi:10.3762/bjoc.11.174

Graphical Abstract
  • and concluded that removal of the leaving group, water, to draw the equilibrium towards polymerization, and the reversal nature of lipase catalysis are two main obstacles. Others have pointed out the latter also [54]. Often a two-step procedure has been used, an initial polymerization to achieve
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Published 09 Sep 2015

Synthesis of a tricyclic lactam via Beckmann rearrangement and ring-rearrangement metathesis as key steps

  • Sambasivarao Kotha,
  • Ongolu Ravikumar and
  • Jadab Majhi

Beilstein J. Org. Chem. 2015, 11, 1503–1508, doi:10.3762/bjoc.11.163

Graphical Abstract
  • amide in the presence of acid was discovered in 1886. This rearrangement involves the migration of a group anti to the leaving group on the nitrogen atom. The BR has widely been used in synthetic organic chemistry, for example, a large-scale production of Nylon-6 is based on the synthesis of ε
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Published 27 Aug 2015

Synthesis of γ-hydroxypropyl P-chirogenic (±)-phosphorus oxide derivatives by regioselective ring-opening of oxaphospholane 2-oxide precursors

  • Iris Binyamin,
  • Shoval Meidan-Shani and
  • Nissan Ashkenazi

Beilstein J. Org. Chem. 2015, 11, 1332–1339, doi:10.3762/bjoc.11.143

Graphical Abstract
  • acids are known to undergo acid and alkaline hydrolysis at rates 105–108 times faster than their acyclic analogs [17]. Thus, cyclic esters may be regarded as a halogen equivalent in terms of their leaving group ability under nucleophilic displacement conditions [18]. The rapid hydrolysis of 2-methoxy
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Published 30 Jul 2015

Design, synthesis and photochemical properties of the first examples of iminosugar clusters based on fluorescent cores

  • Mathieu L. Lepage,
  • Antoine Mirloup,
  • Manon Ripoll,
  • Fabien Stauffert,
  • Anne Bodlenner,
  • Raymond Ziessel and
  • Philippe Compain

Beilstein J. Org. Chem. 2015, 11, 659–667, doi:10.3762/bjoc.11.74

Graphical Abstract
  • buffer conditions were chosen to be as close as possible to the conditions used for β-glucocerebrosidase activation assays (Gaucher disease) which are based on a fluorescent leaving group (4-methylumbelliferone) allowing fluorescence recording after reaction quenching at pH 10.7 [64]. The BODIPY-based
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Published 06 May 2015

Automated solid-phase synthesis of oligosaccharides containing sialic acids

  • Chian-Hui Lai,
  • Heung Sik Hahm,
  • Chien-Fu Liang and
  • Peter H. Seeberger

Beilstein J. Org. Chem. 2015, 11, 617–621, doi:10.3762/bjoc.11.69

Graphical Abstract
  • -chloroacetyl groups on C-7 and C-8 for better α-stereoselectivity [12] produced 3. An α-anomeric phosphate leaving group was chosen since it had previously shown high reactivity [14][18] and selectivity [15]. Building block 4 was obtained in 54% yield over three steps from 1. “Approved building blocks” for
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Published 04 May 2015

3-Glucosylated 5-amino-1,2,4-oxadiazoles: synthesis and evaluation as glycogen phosphorylase inhibitors

  • Marion Donnier-Maréchal,
  • David Goyard,
  • Vincent Folliard,
  • Tibor Docsa,
  • Pal Gergely,
  • Jean-Pierre Praly and
  • Sébastien Vidal

Beilstein J. Org. Chem. 2015, 11, 499–503, doi:10.3762/bjoc.11.56

Graphical Abstract
  • with the N,N’-ditolylcarbodiimide, although the starting material was consumed. The mechanism proposed by Ispikoudi et al. [33] proposes the amine moiety as a leaving group during this process. Anilines (R = tolyl) are worse leaving groups than alkylamines (R = iPr, C6H11), thus providing a likely
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Published 17 Apr 2015

The preparation of new functionalized [2.2]paracyclophane derivatives with N-containing functional groups

  • Henning Hopf,
  • Swaminathan Vijay Narayanan and
  • Peter G. Jones

Beilstein J. Org. Chem. 2015, 11, 437–445, doi:10.3762/bjoc.11.50

Graphical Abstract
  • tetrahedral intermediate thus generated, the polyether bridge functions as a leaving group to form an aldehyde intermediate. This is subsequently reduced a second time to the N-CH3 moiety. In compound 22 one formyl group is still present whereas in 23 this has been lost completely. Both compounds were
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Published 07 Apr 2015

3α,5α-Cyclocholestan-6β-yl ethers as donors of the cholesterol moiety for the electrochemical synthesis of cholesterol glycoconjugates

  • Aneta M. Tomkiel,
  • Adam Biedrzycki,
  • Jolanta Płoszyńska,
  • Dorota Naróg,
  • Andrzej Sobkowiak and
  • Jacek W. Morzycki

Beilstein J. Org. Chem. 2015, 11, 162–168, doi:10.3762/bjoc.11.16

Graphical Abstract
  • the two, the latter appeared to be much more efficient in cholesteryl transfer to the sugar moiety. The problem, however, with 6β-steroidal thioethers is that they are not easily accessible. Therefore, we searched for the best leaving group at C-3. A series of cholesterol derivatives was tested and
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Published 26 Jan 2015

Copper-promoted hydration and annulation of 2-fluorophenylacetylene derivatives: from alkynes to benzo[b]furans and benzo[b]thiophenes

  • Yibiao Li,
  • Liang Cheng,
  • Xiaohang Liu,
  • Bin Li and
  • Ning Sun

Beilstein J. Org. Chem. 2014, 10, 2886–2891, doi:10.3762/bjoc.10.305

Graphical Abstract
  • )ethynyl)benzene were performed, as shown in Scheme 4. In F/Br-substituted 1-bromo-2-(2-(2-fluorophenyl)ethynyl)benzene, the fluoro moiety served as leaving group and gave 2-(2-bromophenyl)benzofuran (2t) as a major product. In F/Cl-substituted 1-chloro-2-(2-(2-fluorophenyl)ethynyl)benzene was able to
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Published 04 Dec 2014

Selenium halide-induced bridge formation in [2.2]paracyclophanes

  • Laura G. Sarbu,
  • Henning Hopf,
  • Peter G. Jones and
  • Lucian M. Birsa

Beilstein J. Org. Chem. 2014, 10, 2550–2555, doi:10.3762/bjoc.10.266

Graphical Abstract
  • . The reaction of 10 with the second equivalent of PhSeCl leads to selenonium ion 11; once the diphenyl diselenide leaving group is formed, the addition of chloride counter-anions from both directions is accompanied by the formation of [2.3.2](1,2,4)cyclophane derivatives 2 and 3. Most probably compound
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Published 31 Oct 2014

Photorelease of phosphates: Mild methods for protecting phosphate derivatives

  • Sanjeewa N. Senadheera,
  • Abraham L. Yousef and
  • Richard S. Givens

Beilstein J. Org. Chem. 2014, 10, 2038–2054, doi:10.3762/bjoc.10.212

Graphical Abstract
  • to be disadvantageous. The recent candidates are based on a pHP motif. Phosphate esters of 10, 14, 24, and acetate 27 [19] each possess a hydroxy donor coupled with an acetyl function bearing the leaving group (Figure 3). One of these, the 5-hydroxy-1-naphthylacetyl motif as its acetate ester 27, has
  • favored by aqueous-based solvents that serve both as a proton donor and an acceptor to the conjugate base generated from the chromophore’s triplet state heterolytic cleavage of the leaving group. The dual behavior of H2O is manifest in accepting a proton from the naphthol OH while simultaneously solvating
  • overall conversion to released substrate. The formation of competing chromophoric byproducts limits the conversion and yields [6][10][11][15]. For example, changing the leaving group for 10, i.e., photolysis of 6-hydroxy-2-naphthylacetyl GABA ester (Figure 2B) inefficiently released 4-aminobutyrate (GABA
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Published 29 Aug 2014

A new charge-tagged proline-based organocatalyst for mechanistic studies using electrospray mass spectrometry

  • J. Alexander Willms,
  • Rita Beel,
  • Martin L. Schmidt,
  • Christian Mundt and
  • Marianne Engeser

Beilstein J. Org. Chem. 2014, 10, 2027–2037, doi:10.3762/bjoc.10.211

Graphical Abstract
  • -tagged catalyst 1 starting from doubly-protected hydroxyproline 6 [57] is depicted in Scheme 3. To introduce a suitable leaving group for the following step of the synthesis, compound 6 was mesylated to give the derivative 7 [58] for which crystals suitable for X-ray analysis have been obtained (Figure 2
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Published 28 Aug 2014

Facile synthesis of 1-alkoxy-1H-benzo- and 7-azabenzotriazoles from peptide coupling agents, mechanistic studies, and synthetic applications

  • Mahesh K. Lakshman,
  • Manish K. Singh,
  • Mukesh Kumar,
  • Raghu Ram Chamala,
  • Vijayender R. Yedulla,
  • Domenick Wagner,
  • Evan Leung,
  • Lijia Yang,
  • Asha Matin and
  • Sadia Ahmad

Beilstein J. Org. Chem. 2014, 10, 1919–1932, doi:10.3762/bjoc.10.200

Graphical Abstract
  • of 1° and 2° alcohols underwent reaction with Bt-OTs giving good to excellent yields of 1-alkoxy-1H-benzotriazoles. Some notable results are as follows. Despite the leaving group ability of BtO−, elimination to styrene does not appear to be a significant problem in the reactions with the isomeric
  • , respectively. We next assessed the leaving group ability of the benzotriazolyloxy group. Although carboxylic acid esters of benzotriazole react efficiently with nucleophiles, this is mechanistically distinct from direct displacement. Thus, four of the 1-alkoxy-1H-benzotriazoles (three 1° and one 2°) were
  • -azidoethyl)benzene, as assessed by 1H NMR. However, this reaction was incomplete and about 12% of 1f remained unreacted. Nevertheless, these results indicate the leaving group ability of BtO− from benzylic sp3 carbon centers and are interesting in the context of the previously unknown reactivity of this
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Published 19 Aug 2014

Application of cyclic phosphonamide reagents in the total synthesis of natural products and biologically active molecules

  • Thilo Focken and
  • Stephen Hanessian

Beilstein J. Org. Chem. 2014, 10, 1848–1877, doi:10.3762/bjoc.10.195

Graphical Abstract
  • attributed in part to the missing α-orientated 4-alkoxy substituent present in sanfetrinem (113), which may act as a potential leaving group and appears to be crucial for activity [97]. Anthoplalone (1999) Isolated from the Okinawan actinian Anthopleura pacifica, anthoplalone (8) is a secosesquiterpene with
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Published 13 Aug 2014

Synthesis of trifluoromethyl-substituted pyrazolo[4,3-c]pyridines – sequential versus multicomponent reaction approach

  • Barbara Palka,
  • Angela Di Capua,
  • Maurizio Anzini,
  • Gyté Vilkauskaité,
  • Algirdas Šačkus and
  • Wolfgang Holzer

Beilstein J. Org. Chem. 2014, 10, 1759–1764, doi:10.3762/bjoc.10.183

Graphical Abstract
  • in 5-chloropyrazole-4-aldehydes is sufficiently activated to act as the leaving group in such kind of C–C linkages [17]. Indeed, reaction of chloroaldehyde 2 with different alkynes 3a–c under typical Sonogashira reaction conditions afforded the corresponding cross-coupling products 4a–c in good
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Published 31 Jul 2014

Expedient synthesis of 1,6-anhydro-α-D-galactofuranose, a useful intermediate for glycobiological tools

  • Luciana Baldoni and
  • Carla Marino

Beilstein J. Org. Chem. 2014, 10, 1651–1656, doi:10.3762/bjoc.10.172

Graphical Abstract
  • -hydroxy group on the anomeric carbon, with the iodide as a good leaving group. This compound is a good precursor for building blocks for the construction of 1→6 linkages. Keywords: 1,6-anhydro-α-D-Galf; galactofuranosyl iodide; galactofuranosyl precursor; per-tert-butyldimethylsilyl-β-D-galactofuranose
  • the formation of the anomeric iodide, the 6-hydroxy group could be desilylated by the acid medium developed during the iodide formation (10 → 11). Then, the free 6-hydroxy group could carry out an intramolecular attack of the anomeric carbon, with iodide as a good leaving group, affording the 1,6
  • leaving group at C-1, and the electron-donating nature of the TBS groups. Thus, while compounds 13 [38] and 14 [39] were prepared by treatment with Lewis acids of fully protected precursors and proved to be stable and therefore useful as synthetic intermediates, attempts to prepare compound 15 by
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Published 21 Jul 2014

A complete series of 6-deoxy-monosubstituted tetraalkylammonium derivatives of α-, β-, and γ-cyclodextrin with 1, 2, and 3 permanent positive charges

  • Martin Popr,
  • Simona Hybelbauerová and
  • Jindřich Jindřich

Beilstein J. Org. Chem. 2014, 10, 1390–1396, doi:10.3762/bjoc.10.142

Graphical Abstract
  • complete series of monosubstituted CD derivatives with a permanent positive charge (Figure 1). Synthesis of monotosylated CDs as the starting material The most crucial and scope-limiting step of the reaction sequence was the introduction of a suitable leaving group in the position 6 of the native CD. For
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Published 18 Jun 2014

Magnesium bis(monoperoxyphthalate) hexahydrate as mild and efficient oxidant for the synthesis of selenones

  • Andrea Temperini,
  • Massimo Curini,
  • Ornelio Rosati and
  • Lucio Minuti

Beilstein J. Org. Chem. 2014, 10, 1267–1271, doi:10.3762/bjoc.10.127

Graphical Abstract
  • they are versatile reagents or intermediates in organic synthesis [1]. Particularly, alkyl phenyl selenones [2][3] represent a valuable compound class due to the ability of the phenylselenonyl group to behave as a good leaving group in substitution reactions (Scheme 1). Thus, the development of
  • different alkyl phenyl selenides to the corresponding selenones. Since the phenylselenonyl group is an excellent leaving group, selenone 2 readily undergoes SN2 type substitution reactions with common nucleophiles [7][8] as shown in Scheme 2. A wide range of heterocyclic compounds can be obtained by
  • bioactive molecules is currently under investigation. General transformation of selenides to selenones. Phenylselenone 2 as useful leaving group for the synthesis of different organic molecules. Oxidation of selenides 1a–d to selenones 2a–d with MMPP. Oxidative cyclization with MMPP of functionalized
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Published 02 Jun 2014

Tandem Cu-catalyzed ketenimine formation and intramolecular nucleophile capture: Synthesis of 1,2-dihydro-2-iminoquinolines from 1-(o-acetamidophenyl)propargyl alcohols

  • Gadi Ranjith Kumar,
  • Yalla Kiran Kumar,
  • Ruchir Kant and
  • Maddi Sridhar Reddy

Beilstein J. Org. Chem. 2014, 10, 1255–1260, doi:10.3762/bjoc.10.125

Graphical Abstract
  • creating initially a leaving group and its subsequent substitution or via activation of the nitrogen atom and direct amination at C-2 while few methods afforded the direct 2-aminoquinoline synthesis from the acyclic precursors. Most recently, we have disclosed a method for the synthesis of E-α,β
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Published 28 May 2014
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