Application of 7-azaisatins in enantioselective Morita–Baylis–Hillman reaction

• Qing He,
• Gu Zhan,
• Wei Du and
• Ying-Chun Chen

Beilstein J. Org. Chem. 2016, 12, 309–313, doi:10.3762/bjoc.12.33

• , all these cases suffered from low reactivity and long reaction times were always required (usually > 48 h) for better conversions. 7-Azaisatins bearing an additional nitrogen atom at the 7-position of the 2-oxindole scaffold might be better electrophiles than isatins owing to the electron-withdrawing

• effect of the pyridine motif. More importantly, a number of 7-azaisatins and 7-azaoxindoles were shown to exhibit significant anticancer or TrkA kinase inhibitory activities (Figure 1) [15][16][17]. This would render their derivatives as pharmaceutically interesting compounds with high potential. In

New metathesis catalyst bearing chromanyl moieties at the N-heterocyclic carbene ligand

• Agnieszka Hryniewicka,
• Szymon Suchodolski,
• Agnieszka Wojtkielewicz,
• Jacek W. Morzycki and
• Stanisław Witkowski

Beilstein J. Org. Chem. 2015, 11, 2795–2804, doi:10.3762/bjoc.11.300

• amounts of unreacted substrates. The high activity of Grela catalyst 3 was a result of faster initiation of the catalytic cycle arising from the electron-withdrawing effect of the nitro group. Consequently, lowered electron density at the oxygen atom in the isopropoxybenzylidene fragment weakens the

Polythiophene and oligothiophene systems modified by TTF electroactive units for organic electronics

• Alexander L. Kanibolotsky,
• Neil J. Findlay and
• Peter J. Skabara

Beilstein J. Org. Chem. 2015, 11, 1749–1766, doi:10.3762/bjoc.11.191

• oxidation waves of the TTF unit in polymers 35, 37, and 39 shifted to significantly higher potentials in comparison to those of the non-brominated monomer compound 14a (+0.46 and +0.83 V, see Table 1) [54]. This can be explained by: 1) the electron-withdrawing effect of the polymer backbone and 2) the

New tris- and pentakis-fused donors containing extended tetrathiafulvalenes: New positive electrode materials for rechargeable batteries

• Shintaro Iwamoto,
• Yuu Inatomi,
• Daisuke Ogi,
• Satoshi Shibayama,
• Yukiko Murakami,
• Minami Kato,
• Kazuyuki Takahashi,
• Kazuyoshi Tanaka,
• Nobuhiko Hojo and
• Yohji Misaki

Beilstein J. Org. Chem. 2015, 11, 1136–1147, doi:10.3762/bjoc.11.128

• shifts of the E5 and E6 of 5d and 7d by 0.62–0.75 V and 0.41–0.63 V, respectively, compared to the E1 and E2 of 3c is probably due to the strong electron-withdrawing effect by two dicationic extended TTF units in the tetracationic states. In other words, the presence of five and six positive charges in

A hybrid electron donor comprising cyclopentadithiophene and dithiafulvenyl for dye-sensitized solar cells

• Gleb Sorohhov,
• Chenyi Yi,
• Michael Grätzel,
• Silvio Decurtins and
• Shi-Xia Liu

Beilstein J. Org. Chem. 2015, 11, 1052–1059, doi:10.3762/bjoc.11.118

• phenyl spacer. Without a phenyl ring, the D unit appears more difficult to oxidize due to a strong electron-withdrawing effect of the A moiety. In sharp contrast, the insertion of the phenyl ring between the D and A units leads to a broken π-conjugation and therefore, the oxidation potentials remain

• affected by the presence of a phenyl spacer. For dye 1, without a phenyl ring, the D unit appears more difficult to oxidize due to a strong the electron-withdrawing effect of the A moiety, and also the lowest-energy absorption band shows a slight bathochromic shift compared to that for dye 2 with a phenyl

• extended hybrid donor as the HOMO is delocalized over the DTF and CPDT moieties. Compared to 6, dye 2 is only marginally more difficult to oxidize as evidenced by slightly more positive values for both oxidation potentials (0.02 V and 0.03 V, respectively, Table 1). This is due to the electron-withdrawing

Synthesis and characterization of the cyanobenzene-ethylenedithio-TTF donor

• Sandrina Oliveira,
• Dulce Belo,
• Isabel C. Santos,
• Sandra Rabaça and
• Manuel Almeida

Beilstein J. Org. Chem. 2015, 11, 951–956, doi:10.3762/bjoc.11.106

• reduces the donor properties, shifting the redox potentials to higher values due to the electron withdrawing effect of the cyano groups possibly with a partial electron transfer from the donor to the acceptor moiety. This tendency is also in agreement with the redox potentials of other cyanobenzene and

Tuning of tetrathiafulvalene properties: versatile synthesis of N-arylated monopyrrolotetrathiafulvalenes via Ullmann-type coupling reactions

• Vladimir A. Azov,
• Diana Janott,
• Dirk Schlüter and
• Matthias Zeller

Beilstein J. Org. Chem. 2015, 11, 860–868, doi:10.3762/bjoc.11.96

• the second to the dication. Non-substituted derivative 4c shows a lower first oxidation potential than its alkylS-substituted counterpart 4a,b, as expected due to the electron-withdrawing effect of the two thioalkyl groups [28][29]. The strong electron-withdrawing effect of the 4-nitrophenyl group in

Trifluoromethyl-substituted tetrathiafulvalenes

• Olivier Jeannin,
• Frédéric Barrière and
• Marc Fourmigué

Beilstein J. Org. Chem. 2015, 11, 647–658, doi:10.3762/bjoc.11.73

• shortening affects the C−S bond closest to the CF3 group demonstrates unambiguously that the mesomeric electron-withdrawing effect of the CN or CO2Me groups is indeed stronger than that of CF3. A similar effect is also observed on the structure of the symmetrical TTF 4bc, which was obtained as symmetrical

• strongest electrostatic interactions between the most electron-rich and electron-poor regions of both partners. In that respect, it appears here that the TCNQ acceptor essentially overlaps with the dithiole ring bearing the dithioethylene substituent, a likely consequence of the electron-withdrawing effect

Weakly nucleophilic potassium aryltrifluoroborates in palladium-catalyzed Suzuki–Miyaura reactions: relative reactivity of K[4-RC₆F₄BF₃] and the role of silver-assistance in acceleration of transmetallation

• Vadim V. Bardin,
• Anton Yu. Shabalin and
• Nicolay Yu. Adonin

Beilstein J. Org. Chem. 2015, 11, 608–616, doi:10.3762/bjoc.11.68

• the data by Sheppard for CCl3F or benzene [45]. When R = H, Bu, or alkoxy group, inductive constants σI (4-RC6F4) consist of 0.16–0.18. The 4-RC6F4 groups with R = F, pyrazol-1-yl, pyrrol-1-yl, indol-1-yl, imidazol-1-yl and benzimidazol-1-yl possess a higher electron-withdrawing effect (σI = 0.21

2-(1-Hydroxypropyn-2-yl)-1-vinylpyrroles: the first successful Favorsky ethynylation of pyrrolecarbaldehydes

• A. V. Ivanov,
• V. S. Shcherbakova,
• I. A. Ushakov,
• L. N. Sobenina,
• O. V. Petrova,
• A. I. Mikhaleva and
• B. A. Trofimov

Beilstein J. Org. Chem. 2015, 11, 228–232, doi:10.3762/bjoc.11.25

• reliable conclusion, although the higher yield of acetylenic alcohol 2d (94%) corresponds to the expectation of the enhanced electron-withdrawing effect of the 3-metoxyphenyl group compared to the unsubstituted phenyl (1c → 2c) that should increase the electrophilicity of the carbonyl function. The range

Highly selective electrochemical fluorination of dithioacetal derivatives bearing electron-withdrawing substituents at the position α to the sulfur atom using poly(HF) salts

• Bin Yin,
• Shinsuke Inagi and
• Toshio Fuchigami

Beilstein J. Org. Chem. 2015, 11, 85–91, doi:10.3762/bjoc.11.12

• -withdrawing effect of a substituent greatly affects the electron-transfer step from the substrate to the anode. At first, anodic fluorination of ethyl α,α-bis(phenylthio)acetate (1b) [30][31] was carried out at platinum plate electrodes in an undivided cell using various solvents in the presence of Et3N·3HF

• dithioacetal 1h having a stronger electron-withdrawing cyano group (Taft σ* = +1.30) [29] are much higher compared to those of 1a, 1b with an ester group (Taft σ* = +0.69) [29] and 1c, 1d with an acetyl group (Taft σ* = +0.60) [29], respectively. This indicates that the polar effect, namely electron

Synthesis and biological evaluation of novel N-α-haloacylated homoserine lactones as quorum sensing modulators

• Michail Syrpas,
• Ewout Ruysbergh,
• Christian V. Stevens,
• Norbert De Kimpe and
• Sven Mangelinckx

Beilstein J. Org. Chem. 2014, 10, 2539–2549, doi:10.3762/bjoc.10.265

• of these possible conformational effects, combined with the electron-withdrawing effect of the halogens, will be subject of future theoretical calculations. Due to the presence of the halogen as an electrophilic moiety, it could be possible that the reduced activity of the novel halogenated analogues

Domino reactions of 2H-azirines with acylketenes from furan-2,3-diones: Competition between the formation of ortho-fused and bridged heterocyclic systems

• Alexander F. Khlebnikov,
• Mikhail S. Novikov,
• Viktoriia V. Pakalnis,
• Roman O. Iakovenko and
• Dmitry S. Yufit

Beilstein J. Org. Chem. 2014, 10, 784–793, doi:10.3762/bjoc.10.74

• . Analysis of the data obtained (Table 2) shows that the ratio of the products 3–5 is determined by the electronic effects of the substituents in the benzene rings both in arylazirine 2 and arylfurandione 1. An increase of the electron-withdrawing effect of substituents in the benzene rings of 3-aryl-2H

• electron withdrawing effect of the nitro group. As for possible routes for the formation of adducts 4 and 5, the first (Scheme 2, (a)) involves cleavage of the aziridine ring of intermediate 8 to generate azomethine ylide 10, and further “dimerization” of the latter. Examples of compounds that can be

• azirine with two molecules of acylketene. The ratio of the adducts 3–5 is determined by electronic effects of the substituents in the benzene rings both in arylazirine 2 and arylfurandione 1. The increase of the electron-withdrawing effect of the substituents in the benzene rings of the arylazirine leads

A novel family of (1-aminoalkyl)(trifluoromethyl)- and -(difluoromethyl)phosphinic acids – analogues of α-amino acids

• Natalia V. Pavlenko,
• Tatiana I. Oos,
• Yurii L. Yagupolskii,
• Igor I. Gerus,
• Uwe Doeller and
• Lothar Willms

Beilstein J. Org. Chem. 2014, 10, 722–731, doi:10.3762/bjoc.10.66

• storage in a ratio of ~ 3:2 with acid 1 as an impurity. The low stability of all three esters 2–4 can be attributed to the lability of the O–C ester bond, resulting from the electron-withdrawing effect of the CF3 group attached to phosphorus, therefore esters 2, 3 and 4 were used in the syntheses only

Regioselective carbon–carbon bond formation of 5,5,5-trifluoro-1-phenylpent-3-en-1-yne

• Motoki Naka,
• Tomoko Kawasaki-Takasuka and
• Takashi Yamazaki

Beilstein J. Org. Chem. 2013, 9, 2182–2188, doi:10.3762/bjoc.9.256

• electrophiles, under equilibration of the possible two anionic species. Keywords: additives; computation; Li···F chelation; deprotonation; electron-withdrawing effect; organo-fluorine; Introduction We have previously reported [1] the interesting behavior of (E)-1-chloro-3,3,3-trifluoropropene ((E)-1) [2][3][4

Cyclization of substitued 2-(2-fluorophenylazo)azines to azino[1,2-c]benzo[d][1,2,4]triazinium derivatives

• Aleksandra Jankowiak,
• Emilia Obijalska and
• Piotr Kaszynski

Beilstein J. Org. Chem. 2013, 9, 1873–1880, doi:10.3762/bjoc.9.219

• cyclization was carried out with sunlight and tosylate 1c was isolated in pure form in 90% yield. In contrast, cation 1d partially decomposed during the workup, presumably due to the activation by means of the fluorine atoms and their electron-withdrawing effect. A pure sample of 1d could not be isolated. A

Incorporation of perfluorohexyl-functionalised thiophenes into oligofluorene-truxenes: synthesis and physical properties

• Neil Thomson,
• Alexander L. Kanibolotsky,
• Joseph Cameron,
• Tell Tuttle,
• Neil J. Findlay and
• Peter J. Skabara

Beilstein J. Org. Chem. 2013, 9, 1243–1251, doi:10.3762/bjoc.9.141

• percentage of fluorine present gives rise to a large electron-withdrawing effect [11]. However, perfluoroalkyl halides are not suitable alkylating reagents for SN2 type reactions, which makes the attachment of these types of chains to aromatic cyclic compounds difficult without the use of a spacer group

Easy and direct conversion of tosylates and mesylates into nitroalkanes

• Alessandro Palmieri,
• Serena Gabrielli and
• Roberto Ballini

Beilstein J. Org. Chem. 2013, 9, 533–536, doi:10.3762/bjoc.9.58

• electron-withdrawing effect of the nitro group, nitroalkanes are prone to afford, under basic conditions, stabilized carbanions, which are commonly used as nucleophiles with a variety of electrophiles [8][9][10][11] leading to carbon–carbon bond formation. Furthermore, by making use of the possibility to

A one-pot catalyst-free synthesis of functionalized pyrrolo[1,2-a]quinoxaline derivatives from benzene-1,2-diamine, acetylenedicarboxylates and ethyl bromopyruvate

• Mohammad Piltan,
• Loghman Moradi,
• Golaleh Abasi and
• Seyed Amir Zarei

Beilstein J. Org. Chem. 2013, 9, 510–515, doi:10.3762/bjoc.9.55

• (Table 1, entries d, e and h), while a nitro group did not participate in the reaction (Table 1, entries f and g). It seems that the high electron-withdrawing effect of the nitro group deactivates the amine. Although the mechanistic details of the reaction are not known, a plausible mechanism maybe put

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

• nucleophilicities of the imidazolidinone derived enamines, which are in line with the larger 13C NMR chemical shifts of C-2 in 32d (101.9 ppm) and 32e (102.9 ppm) compared to that of C-2 in 32a (97.4 ppm), are not only due to the electron-withdrawing effect of the additional heteroatoms in the heterocyclic rings

• their deoxy analogues 61 and 45b, respectively. Obviously, the transition state is more affected by the destabilization of the cationic adduct due to the inductive electron-withdrawing effect than by the +M-effect of the methoxy group, which raises the HOMO of the reactants. Replacement of the sulfur

Low-generation dendrimers with a calixarene core and based on a chiral C₂-symmetric pyrrolidine as iminosugar mimics

• Marco Marradi,
• Stefano Cicchi,
• Francesco Sansone,
• Alessandro Casnati and
• Andrea Goti

Beilstein J. Org. Chem. 2012, 8, 951–957, doi:10.3762/bjoc.8.107

• deshielding effect on the aromatic protons of about 0.3 ppm with respect to the free calixarene (as indicated by the asterisks) as a consequence of the electron-withdrawing effect of the metal ion coordinated to the phenolic oxygen. Quite remarkable is the up-field shift exerted by the OCH2CON protons (empty

Discovery of practical production processes for arylsulfur pentafluorides and their higher homologues, bis- and tris(sulfur pentafluorides): Beginning of a new era of “super-trifluoromethyl” arene chemistry and its industry

• Teruo Umemoto,
• Lloyd M. Garrick and
• Norimichi Saito

Beilstein J. Org. Chem. 2012, 8, 461–471, doi:10.3762/bjoc.8.53

• nuclei are deactivated by the electron-withdrawing effect of the halogen atoms. It was also found that when PhSF4Cl (2a) was treated with a 70:30 w/w mixture of HF–pyridine at 55 °C, it gave PhSF5 (3a) in 63% isolated yield (Scheme 7). The HF–pyridine reagent is a nonvolatile and easily handled chemical

Fluorescent hexaaryl- and hexa-heteroaryl[3]radialenes: Synthesis, structures, and properties

• Antonio Avellaneda,
• Courtney A. Hollis,
• Xin He and
• Christopher J. Sumby

Beilstein J. Org. Chem. 2012, 8, 71–80, doi:10.3762/bjoc.8.7

• difficult to reduce. Conversely, compound 3 is very easy to reduce. This is shown by its reduction potentials of −0.06 and −0.45 V, respectively, and is attributed to the combined electron-withdrawing effect of the twelve nitrile substituents. While compound 3 is considerably more electron deficient than

Asymmetric synthesis of quaternary aryl amino acid derivatives via a three-component aryne coupling reaction

• Elizabeth P. Jones,
• Peter Jones,
• Andrew J. P. White and
• Anthony G. M. Barrett

Beilstein J. Org. Chem. 2011, 7, 1570–1576, doi:10.3762/bjoc.7.185

• exposure to 0.5 M HCl, epimerization of the isopropyl group at C-3 occurs in near quantitative yield, giving adduct 13 (Scheme 10). The electron-withdrawing effect of the carbonyl moiety must increase the acidity of the C-3 proton to such an extent that the acidic media simply epimerizes at this center to

Functionalization of heterocyclic compounds using polyfunctional magnesium and zinc reagents

• Paul Knochel,
• Matthias A. Schade,
• Sebastian Bernhardt,
• Georg Manolikakes,
• Albrecht Metzger,
• Fabian M. Piller,
• Christoph J. Rohbogner and
• Marc Mosrin

Beilstein J. Org. Chem. 2011, 7, 1261–1277, doi:10.3762/bjoc.7.147

• regioselectivity is explained by the polar and electron-poor nature of the tosyloxy group, which leads to a strong electron-withdrawing effect and accelerates the insertion of zinc into the neighboring C–I bond. The presence of LiCl amplifies this effect through coordination to the tosyloxy group and to the ortho