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Search for "Michael acceptor" in Full Text gives 78 result(s) in Beilstein Journal of Organic Chemistry.

Cupreines and cupreidines: an established class of bifunctional cinchona organocatalysts

  • Laura A. Bryant,
  • Rossana Fanelli and
  • Alexander J. A. Cobb

Beilstein J. Org. Chem. 2016, 12, 429–443, doi:10.3762/bjoc.12.46

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  • (Scheme 11a) [38]. Subsequent reports by Deng and co-workers include, amongst many varieties of Michael acceptor and donor with various CPN/CPD derivatives [39][40][41], an example where β-ketoesters are used as the nucleophilic component [42]. It is on the basis of this work that Lin and co-workers were
  • cyclopropanation using dimethyl bromomalonate (57) and some form of Michael acceptor. In this process, the enolate resulting from the initital conjugate addition attacks the C–Br bond to form a three-membered ring. In our work in this area, we designed a new cupreine derived catalyst HCPN-59 to add dimethyl
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Published 07 Mar 2016

Facile synthesis of 4H-chromene derivatives via base-mediated annulation of ortho-hydroxychalcones and 2-bromoallyl sulfones

  • Srinivas Thadkapally,
  • Athira C. Kunjachan and
  • Rajeev S. Menon

Beilstein J. Org. Chem. 2016, 12, 16–21, doi:10.3762/bjoc.12.3

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  • an added incentive for this investigation [1]. We envisaged that the presence of a Michael acceptor double bond at the ortho position of a phenol would offer avenues for carbon–carbon bond forming annulation in its reaction with 2a,b. In view of their well-known reactivity profiles, diversity options
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Published 06 Jan 2016

Copper-catalyzed asymmetric conjugate addition of organometallic reagents to extended Michael acceptors

  • Thibault E. Schmid,
  • Sammy Drissi-Amraoui,
  • Christophe Crévisy,
  • Olivier Baslé and
  • Marc Mauduit

Beilstein J. Org. Chem. 2015, 11, 2418–2434, doi:10.3762/bjoc.11.263

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  • various scenarios that can be expected with an α,β,γ,δ-unsaturated Michael acceptor. Amongst the variety of transition-metal-based catalytic systems that have been evaluated in ACA reactions on extended Michael acceptors [1][3], copper-based systems have been the subject of tremendous interest, which
  • compound to an extended Michael acceptor was reported independently as early as 1972, by the Näf [4] and Corey [5] groups, who studied the reactivity of pentadienyl methyl ester (1, Figure 2). In both cases, the 1,6-conjugate addition of a stoichiometric amount of a Gilman reagent proceeded in a selective
  • selectively afforded the 1,6-adduct 21 in 53% yield and 68% ee (Scheme 10). Displaying a similar reactivity, bicyclic Michael acceptor 40 led to compound 41 in 45% yield and 69% ee. In 2010, the Alexakis group explored the reactivity of α,β,γ,δ-unsaturated nitroolefins and nitroenynes in Cu-catalyzed ACA
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Published 03 Dec 2015

One-pot odourless synthesis of thioesters via in situ generation of thiobenzoic acids using benzoic anhydrides and thiourea

  • Mohammad Abbasi and
  • Reza Khalifeh

Beilstein J. Org. Chem. 2015, 11, 1265–1273, doi:10.3762/bjoc.11.141

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  • thiobenzoate anion. Finally, the thiobenzoate reacts with a Michael acceptor or an alkyl halide to give the thioester product. Conclusion In conclusion, an efficient, versatile, and odourless protocol for a one-pot preparation of thioesters from non-thiolic precursors under mild conditions has been developed
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Published 28 Jul 2015

The synthesis of active pharmaceutical ingredients (APIs) using continuous flow chemistry

  • Marcus Baumann and
  • Ian R. Baxendale

Beilstein J. Org. Chem. 2015, 11, 1194–1219, doi:10.3762/bjoc.11.134

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  • small collection of 22 imidazo[1,2-a]pyridines 136 was prepared within four working days. The synthetic route consisted of an aldol condensation between various acetophenones 137 and ethyl glyoxylate (138). This was followed by an HBF4-catalysed cyclocondensation of the resulting Michael acceptor 139
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Published 17 Jul 2015

Synthesis of tripodal catecholates and their immobilization on zinc oxide nanoparticles

  • Franziska Klitsche,
  • Julian Ramcke,
  • Julia Migenda,
  • Andreas Hensel,
  • Tobias Vossmeyer,
  • Horst Weller,
  • Silvia Gross and
  • Wolfgang Maison

Beilstein J. Org. Chem. 2015, 11, 678–686, doi:10.3762/bjoc.11.77

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  • ] were converted to the corresponding triscatecholates 11 and 13 by coupling to dopamine (Scheme 2). The resulting triscatecholates 11 and 13 may be used as synthetically flexible platforms for functionalizations of surfaces via either nucleophilic addition (to the Michael acceptor in 11) or radical
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Published 07 May 2015

Diastereoselective and enantioselective conjugate addition reactions utilizing α,β-unsaturated amides and lactams

  • Katherine M. Byrd

Beilstein J. Org. Chem. 2015, 11, 530–562, doi:10.3762/bjoc.11.60

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  • (97:3) [64]. Following a series of steps, the 1,4-addition products were converted to either (+)-paroxetine (R = p-FC6H4) or (+)-femoxetine (R = C6H5) (Scheme 7). 1.2 DCA to inherently chiral Michael acceptors When DCA reactions are performed using a chiral Michael acceptor, the diastereoselectivity
  • is dictated by the overall stereochemistry of the Michael acceptor. The advantage of this approach over the use of a chiral auxiliary is that the addition and removal of a group to induce diastereoselectivity is not required, hence making this approach more atom economical. The disadvantage of
  • performing DCA reactions using chiral substrates is that the overall stereochemistry of the Michael acceptor may either produce the undesired diastereomer in high yield or a low diastereoselectivity may be observed. Due to the complex nature of the chiral starting material, structural changes that would
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Published 23 Apr 2015

Morita–Baylis–Hillman reaction of acrylamide with isatin derivatives

  • Radhey M. Singh,
  • Kishor Chandra Bharadwaj and
  • Dharmendra Kumar Tiwari

Beilstein J. Org. Chem. 2014, 10, 2975–2980, doi:10.3762/bjoc.10.315

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  • , the acryl system shows differences in reactivity upon slight structural modifications. In such a system, the enone and acrylonitrile are more reactive, while with the acrylate reaction is relatively slow. Furthermore, there is a decrease of reactivity with acrylamide due to the reduced Michael
  • acceptor tendency of alkene, which retards the attack of the catalyst on alkene, thus hindering the initiation of a reaction (Figure 1). Thus acrylamide has least contributed to the success of this reaction in the last four decades. In an effort to address the slow reaction rate of acrylamide, Hu et al
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Published 12 Dec 2014

Stereoselective synthesis of perillaldehyde-based chiral β-amino acid derivatives through conjugate addition of lithium amides

  • Zsolt Szakonyi,
  • Reijo Sillanpää and
  • Ferenc Fülöp

Beilstein J. Org. Chem. 2014, 10, 2738–2742, doi:10.3762/bjoc.10.289

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  • ]. Results and Discussion The key intermediate Michael acceptor, tert-butyl perillate (3), was prepared by a combination of literature protocols, starting from commercially available (−)-(4S)-perillaldehyde (1) in a two-step reaction. First, oxidation of 1 led to perillic acid (2) [36], which was
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Published 21 Nov 2014

Chiral phosphines in nucleophilic organocatalysis

  • Yumei Xiao,
  • Zhanhu Sun,
  • Hongchao Guo and
  • Ohyun Kwon

Beilstein J. Org. Chem. 2014, 10, 2089–2121, doi:10.3762/bjoc.10.218

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  • 2010, using the bifunctional chiral phosphine G1, bearing both Brønsted acid and Lewis base units, as the catalyst, asymmetric domino aza-MBH/aza-Michael reactions of activated alkenes and N-tosylimines with Michael acceptor moieties at their ortho positions were accomplished to give chiral 1,3
  • proposed that the major enantiomer formed through re-face attack of the ylide onto the Michael acceptor, rather than attack from the sterically hindered si-face. 2.16 Michael additions Asymmetric Michael addition is one of the most studied enantioselective processes in organic synthesis, with many
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Published 04 Sep 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

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  • cyclopropane 50a. Starting with (cis,R,R)-47b, the isomeric exo,endo product 50b is obtained as major isomer. The cyclopropanation reaction tolerates a wide range of Michael acceptor subtrates such as enones, lactones, lactams, and acyclic α,β-unsaturated esters. The obtained products can easily be cleaved to
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Published 13 Aug 2014

Synthesis and bioactivity of analogues of the marine antibiotic tropodithietic acid

  • Patrick Rabe,
  • Tim A. Klapschinski,
  • Nelson L. Brock,
  • Christian A. Citron,
  • Paul D’Alvise,
  • Lone Gram and
  • Jeroen S. Dickschat

Beilstein J. Org. Chem. 2014, 10, 1796–1801, doi:10.3762/bjoc.10.188

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  • TDA. The introduction of sulfur proceeds via nucleophilic attack of S-thiocysteine to the Michael acceptor of tropone-2-carboxylic acid coenzyme A ester and oxidative elimination of cysteine. The second sulfur atom is introduced by analogous attack to the vinylogous Michael acceptor. The volatiles
  • by the nucleophilic attack of fluoride to the Michael acceptor in 20 followed by elimination of chloride. In contrast, treatment of 19 with potassium carbonate in MeOH yielded only minor amounts of 20 and the substitution product, methoxy derivative 22, as main product. All three compounds 20–22 were
  • cycloheptanone derivatives with rigorously simplified structures as compared to TDA were included in this study. The β-ketoester 27 containing a Michael acceptor was synthesised from methyl cycloheptanone-2-carboxylate (26) by oxidation with Cu(OAc)2 and Pb(OAc)2 according to a known procedure [16]. The compound
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Published 06 Aug 2014

Preparation of phosphines through C–P bond formation

  • Iris Wauters,
  • Wouter Debrouwer and
  • Christian V. Stevens

Beilstein J. Org. Chem. 2014, 10, 1064–1096, doi:10.3762/bjoc.10.106

Graphical Abstract
  • by Glueck [118][119] and Pullarkat and Leung [120]. Some recent developments in the asymmetric catalytic hydrophosphination will be discussed. The group of Glueck reported on an approach to chiral phosphines by the addition of secondary phosphines 36c to Michael acceptor alkenes (acrylonitrile or
  • giving a platinum–phosphido complex. Subsequent nucleophilic attack on a Michael acceptor alkene was suggested to lead to a zwitterion intermediate. Addition of a protic additive was beneficial for the selectivity and reaction rate [95]. Several chiral cyclic phosphines were acquired via the lanthanide
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Published 09 May 2014

An overview of the synthetic routes to the best selling drugs containing 6-membered heterocycles

  • Marcus Baumann and
  • Ian R. Baxendale

Beilstein J. Org. Chem. 2013, 9, 2265–2319, doi:10.3762/bjoc.9.265

Graphical Abstract
  • formed and subsequently undergoes cyclocondensation with the Michael acceptor 1.36 as the rate determining step of this sequence [30]. Other important species containing a pyridine moiety are rosiglitazone (1.40, Avandia) and pioglitazone (1.41, Actos), which are members of the so called
  • install the different ester groups as well as the aminoethanol appendage. In a patented route to this compound the assembly is realised using a stepwise condensation between enamine 2.6, which already contains the masked aminoethanol unit, and the advanced Michael acceptor 2.7 delivering dihydropyridine
  • available 3-aminocrotonate (2.27) which subsequently undergoes the Hantzsch reaction with the elaborate Michael acceptor 2.26. The fully reduced pyridine unit, the piperidine ring system, is one of the most frequently encountered heterocycles found in pharmaceutical agents, typically acting either as a
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Published 30 Oct 2013

The chemistry of amine radical cations produced by visible light photoredox catalysis

  • Jie Hu,
  • Jiang Wang,
  • Theresa H. Nguyen and
  • Nan Zheng

Beilstein J. Org. Chem. 2013, 9, 1977–2001, doi:10.3762/bjoc.9.234

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  • the adduct 80, thus completing the catalytic cycle. The authors performed two control studies to probe the involvement of the α-amino radical 17. The first study was to irradiate N-phenyltetrahydroisoquinoline 13 in the absence of the Michael acceptor under otherwise identical conditions. The dimer
  • of the reaction; NMP produced much higher yields of the products 89 than DMF, while no products were formed in MeCN or MeOH. The authors interrogated the intermediacy of the α-amino radical 88 by treatment of diphenylmethylaniline with a Michael acceptor incorporating a cyclopropyl ring 95. The ring
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Published 01 Oct 2013

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

Graphical Abstract
  • suitable counterions for the activation of the Michael acceptor, with 94% isolated yield (Table 1, entries 3 and 4). Sodium and potassium ions are slightly less sufficient with yields up to 72% (sodium, Table 1, entry 5) or 74% (potassium, Table 1, entry 10). Zinc does almost not work at all (yields are 5
  • states TS-13 and TS-14 differ by 10.8 kcal/mol, whereby TS-14 is the favored. Intermediate 16 is 7.2 kcal lower in energy than 15. Hence, it is apparent that the enantio-determining step of the addition to the Michael acceptor is TS-14. Another point of interest in the mechanistic study is how
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Published 23 Jan 2013

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

Graphical Abstract
  • the literature up to 2011. Keeping an overview of organocatalytic modes of activation, and taking the less reactive Michael acceptor into account, we discuss here only the iminium/enamine activation or dual activation by iminium and hydrogen-bonding interaction strategies followed by cyclization, for
  • of 1 and 2. A potential “one-pot” approach to the organocatalytic synthesis of chiral 4H-chromenes was first reported by Wang and co-workers [47]. In an unprecedented oxa-Michael–aldol cascade sequence, reactions of (2-hydroxyphenyl)-2-oxoacetates 4 (Michael donor) and alkynals 5 (Michael acceptor
  • intermediate. A wide range of readily available Michael acceptor α,β-unsaturated aldehydes are tolerated in the reaction. The protection group of the amino function also governs both reactivity and enantioselectivity. The Cbz-protected aminobenzaldehydes in dichloroethane afford the best results in a shorter
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Published 04 Oct 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
  • the nucleophile to the tertiary amino group between the side chains of the catalysts. The re-face of the Michael acceptor is shielded by the flat quinoline unit and the si-attack of the malonate is preferred, affording R-selectivity (Figure 3). Determination of the absolute configuration The absolute
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Published 04 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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  • guanidine motif have only a moderate influence on the affinity to the acetyl cation. Michael-acceptor affinities (MAA) A large number of reactions induced or catalyzed by Lewis bases involve initial or rate-limiting reaction with neutral electrophiles such as alkyl halides (substitution) or Michael
  • acceptors (addition). Taking the (aza-)Morita–Baylis–Hillman reaction as an example the first step of the catalytic cycle involves the attack of N- or P-centered nucleophiles to a Michael acceptor (equation 10, Scheme 10). In contrast to the Lewis base additions to cationic electrophiles discussed above, in
  • affinity (MOSCA) of a Lewis base. Reactions for the acetyl cation affinity (ACA) of a Lewis base (9a) and pyridine (9b). Reaction for the Michael-acceptor affinity (MAA) of a Lewis base. (a) General definition for a methyl cation transfer reaction between Lewis bases LB1 and LB2, and (b) methyl cation
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Published 31 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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  • -diaryloxindoles. It also came to our attention that, while the addition of 3-prochiral oxindole to a variety of Michael acceptors had been studied [32][33][34][35][36][37][38][39][40][41][42][43][44][45][46], the use of quinones as the Michael acceptor had not been realized. Therefore, in this letter we are going
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Published 23 Aug 2012

Two-directional synthesis as a tool for diversity-oriented synthesis: Synthesis of alkaloid scaffolds

  • Kieron M. G. O’Connell,
  • Monica Díaz-Gavilán,
  • Warren R. J. D. Galloway and
  • David R. Spring

Beilstein J. Org. Chem. 2012, 8, 850–860, doi:10.3762/bjoc.8.95

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  • a nucleophilic amino group with suitable electrophilic functionality, provided by Michael acceptor α,β-unsaturated ester groups. Two-directional synthesis was used to append these electrophilic groups at two positions around the linear substrates, allowing bicyclisation processes to be instigated
  • form a stable hydrogen-bonded species with the NH group that inhibits the reaction of the nitrogen with the Michael acceptor ester groups. Studies involving the use of Tris as a potential DOS substrate remain on-going within our laboratories. Conclusion The work presented in this article serves to
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Published 06 Jun 2012

Amines as key building blocks in Pd-assisted multicomponent processes

  • Didier Bouyssi,
  • Nuno Monteiro and
  • Geneviève Balme

Beilstein J. Org. Chem. 2011, 7, 1387–1406, doi:10.3762/bjoc.7.163

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  • series of benzo-fused sultams. A range of α-bromobenzenesulfonyl chlorides 40 were first coupled with various amines in DMF at room temperature in the presence of Et3N to generate intermediate sulfonamides 41. Subsequent in situ addition of a Michael acceptor in large excess together with Et3N, Bu4NCl
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Published 10 Oct 2011

An overview of the key routes to the best selling 5-membered ring heterocyclic pharmaceuticals

  • Marcus Baumann,
  • Ian R. Baxendale,
  • Steven V. Ley and
  • Nikzad Nikbin

Beilstein J. Org. Chem. 2011, 7, 442–495, doi:10.3762/bjoc.7.57

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  • ) with cyclohexan-1,3-dione (Scheme 38). Classical N-methylation with dimethyl sulfate followed by introduction of an exocyclic double bond using paraformaldehyde in DMF under acidic conditions furnishes the Michael acceptor 189, which then undergoes conjugate addition with various amines (Scheme 38
  • -aminopropionaldehyde diethylacetal 32 in toluene under mildly acidic conditions to afford the fully substituted pyrrole motif in 81% isolated yield following crystallisation [6]. The key transformation in this sequence is a thiazolium-mediated Stetter reaction between 4-fluorobenzaldehyde (29) and an advanced Michael
  • acceptor obtained from an initial Knoevenagel condensation (Scheme 5). In order to improve the overall yield as well as the convergency, the industrial route [7] introduced the fully elaborated side chain 34 by condensation with the previously described 1,4-diketone 31 (Scheme 5 and Scheme 6). The desired
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Published 18 Apr 2011

Michael-type addition of azoles of broad-scale acidity to methyl acrylate

  • Sławomir Boncel,
  • Kinga Saletra,
  • Barbara Hefczyc and
  • Krzysztof Z. Walczak

Beilstein J. Org. Chem. 2011, 7, 173–178, doi:10.3762/bjoc.7.24

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  • donors. The azoles derivatives (1a–h) were subjected to the reaction with methyl acrylate (2) (Michael acceptor) in the presence of an appropriate base, namely DBU (pKa = 12 [28]), diisopropylethylamine (DIPEA, Hünig’s base, pKa = 10.75 [29]), NaOH (pKa = 15.7 [30]), NaH (pKa = 37 [29]) or TEDA (pKa
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Published 08 Feb 2011

Synthesis of gem-difluoromethylenated analogues of boronolide

  • Jing Lin,
  • Xiao-Long Qiu and
  • Feng-Ling Qing

Beilstein J. Org. Chem. 2010, 6, No. 37, doi:10.3762/bjoc.6.37

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  • demonstrated that the α,β-unsaturated-δ-lactone moiety plays a key role in the bioactivity of many natural products. This is due to the fact that this unit is an excellent potential Michael acceptor for nucleophilic amino acid residues of the natural receptors interacting with these compounds [16][17][18
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Published 20 Apr 2010
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