Copper-catalyzed [3 + 2] cycloaddition of (phenylethynyl)di-p-tolylstibane with organic azides

• Mizuki Yamada,
• Mio Matsumura,
• Yuki Uchida,
• Masatoshi Kawahata,
• Yuki Murata,
• Naoki Kakusawa,
• Kentaro Yamaguchi and
• Shuji Yasuike

Beilstein J. Org. Chem. 2016, 12, 1309–1313, doi:10.3762/bjoc.12.123

• the reaction of the Cu(I) catalyst and ethynylstibane 1. Complex A coordinates with an organic azide to give complex B. Cyclization proceeds via a vinylidene-like transition state C to give 5-stibanotriazole 3. To test the reactivity of 5-stibanotriazole 3a was treated with hydrochloric acid, halogens

Cationic Pd(II)-catalyzed C–H activation/cross-coupling reactions at room temperature: synthetic and mechanistic studies

• Takashi Nishikata,
• Alexander R. Abela,
• Shenlin Huang and
• Bruce H. Lipshutz

Beilstein J. Org. Chem. 2016, 12, 1040–1064, doi:10.3762/bjoc.12.99

• in good yields (5l, 5m, 5n). Arylureas containing halogens, which are slightly electron-deficient but provide useful synthetic handles for subsequent functionalization, reacted cleanly to form the desired products (5p, 5q). Arylureas bearing ortho-alkyl substituents also gave excellent yields (5o, 5r

(Thio)urea-mediated synthesis of functionalized six-membered rings with multiple chiral centers

• Giorgos Koutoulogenis,
• Nikolaos Kaplaneris and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2016, 12, 462–495, doi:10.3762/bjoc.12.48

• ]. Initially nitromethane adds to the chalcone moiety, followed by a nitronate addition to the α,β-unsaturated ester. The substrate scope was widely expanded, including the aromatic moieties containing halogens, alkyl and alkoxy groups. Also, ketones bearing aryl, heteroaryl and alkyl groups, provided the

An efficient synthesis of N-substituted 3-nitrothiophen-2-amines

• Sundaravel Vivek Kumar,
• Shanmugam Muthusubramanian,
• J. Carlos Menéndez and
• Subbu Perumal

Beilstein J. Org. Chem. 2015, 11, 1707–1712, doi:10.3762/bjoc.11.185

• . Regarding aryl substituents, the thiophene synthesis was compatible with the presence of unsubstituted phenyl rings (compound 3e) and phenyl substituents bearing moderately electron-withdrawing groups such as m- and p-halogens and m-trifluoroalkyl substituents (compounds 3a–d and 3l–n), although substrates

N-Alkyl derivatives of diosgenyl 2-amino-2-deoxy-β-D-glucopyranoside; synthesis and antimicrobial activity

• Agata Walczewska,
• Daria Grzywacz,
• Dorota Bednarczyk,
• Małgorzata Dawgul,
• Andrzej Nowacki,
• Wojciech Kamysz,
• Beata Liberek and
• Henryk Myszka

Beilstein J. Org. Chem. 2015, 11, 869–874, doi:10.3762/bjoc.11.97

• with bromides 2a, 2b and 2d are higher than those with analogous chlorides 3a, 3b and 3d. However, reactivity of chloride 3c is stronger than that of analogous bromide 2c. (N-Phenyl)trifluoroacetimidates (5a–d) seem to be quite effective glycosyl donors. However their comparison with halogens 2a–d and

Functionalized branched EDOT-terthiophene copolymer films by electropolymerization and post-polymerization “click”-reactions

• Miriam Goll,
• Adrian Ruff,
• Erna Muks,
• Felix Goerigk,
• Beatrice Omiecienski,
• Ines Ruff,
• Rafael C. González-Cano,
• Juan T. Lopez Navarrete,
• M. Carmen Ruiz Delgado and
• Sabine Ludwigs

Beilstein J. Org. Chem. 2015, 11, 335–347, doi:10.3762/bjoc.11.39

• polymers from organic solvents to water solubility [44]. “Electro-click” modifications were used for chemically synthesized PEDOT-N3 and copolymers of EDOT-N3 and EDOT with halogens and fluorescent markers [45][46] and of electrochemically synthesized PEDOT-N3 to introduce fluorinated alkyl chains [47]. In

Cross-dehydrogenative coupling for the intermolecular C–O bond formation

• Igor B. Krylov,
• Vera A. Vil’ and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2015, 11, 92–146, doi:10.3762/bjoc.11.13

• -heterocyclic carbenes was used for the kinetic separation of enantiomers of alcohols [125][126]. 2.4 Reactions using halogen-containing oxidative systems This section considers cross-dehydrogenative C–O coupling reactions with aldehydes and primary alcohols as C-reagents in which halogens and their compounds

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

• lactone carbonyl group, could increase the affinity of AHLs to their cognate receptors [18]. It was shown that introduction of halogens as electron-withdrawing groups in the N-acyl chain reduced the nucleophilicity of the donor oxygen and led to attenuation of the n→π* interaction (Figure 1). Moreover

• 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

• in activity as compared to the activity of the corresponding natural analogues with the same N-acyl chain in the E. coli JB523 bioassay. These results do not directly support the recent suggestion that modifications, i.e., introduction of halogens that weakens the n→π* interaction should increase the

Superoxide chemistry revisited: synthesis of tetrachloro-substituted methylenenortricyclenes

• Basavaraj M. Budanur and
• Faiz Ahmed Khan

Beilstein J. Org. Chem. 2014, 10, 2531–2538, doi:10.3762/bjoc.10.264

• synthesis of natural and aesthetically pleasing unnatural products. During our endeavour, we were selectively removing the halogens, utilizing them as transformation tools [33][34][35][36]. Our continued interest in this direction led us to explore the chemistry of alkylpentachlorocyclopentadienes as they

A simple copper-catalyzed two-step one-pot synthesis of indolo[1,2-a]quinazoline

• Chunpu Li,
• Lei Zhang,
• Shuangjie Shu and
• Hong Liu

Beilstein J. Org. Chem. 2014, 10, 2441–2447, doi:10.3762/bjoc.10.254

• product (Table 2, entry 3). This result may be attributed to its low stability during the reaction. In comparison, electron-withdrawing p-trifluoromethyl and ester-substituted N-(2-iodophenyl)acetamides led to decreased yields of the desired compounds (Table 2, entries 4 and 5). Various halogens (F, Cl

Scalable synthesis of 5,11-diethynylated indeno[1,2-b]fluorene-6,12-diones and exploration of their solid state packing

• Bradley D. Rose,
• Peter J. Santa Maria,
• Aaron G. Fix,
• Chris L. Vonnegut,
• Lev N. Zakharov,
• Sean R. Parkin and
• Michael M. Haley

Beilstein J. Org. Chem. 2014, 10, 2122–2130, doi:10.3762/bjoc.10.219

• overcome the synthetic roadblock that Scheme 1 represented. The improved synthetic route to 8 arises from a retrosynthetic analysis of the current method to prepare IF derivatives [9][10][11][13]. The needed modification must include halogens at the 5 and 11 positions for subsequent functionalization, such

Direct C–H trifluoromethylation of di- and trisubstituted alkenes by photoredox catalysis

• Ren Tomita,
• Yusuke Yasu,
• Takashi Koike and
• Munetaka Akita

Beilstein J. Org. Chem. 2014, 10, 1099–1106, doi:10.3762/bjoc.10.108

• electron-donating substituents, MeO (2b), and halogens, Cl (2c) and Br (2d), smoothly produced the corresponding trisubstituted CF3-alkenes (3b–d) in good yields. In the reactions of unsymmetrically substituted substrates (2e–h), products were obtained in good to moderate yields but consisted of mixtures

Halogenated volatiles from the fungus Geniculosporium and the actinomycete Streptomyces chartreusis

• Tao Wang,
• Patrick Rabe,
• Christian A. Citron and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2013, 9, 2767–2777, doi:10.3762/bjoc.9.311

• , but the overall trend is similar, and therefore chlorine and bromine are also the most widespread halogens in natural products from terrestrial organisms. Many biologically active halogenated secondary metabolites are known from actinomycetes including vancomycin [4], chloramphenicol [5], rebeccamycin

• global chloroform emissions [12]. The introduction of halogens into natural products is catalysed by various known types of enzymes [13][14], including the FADH2-dependent halogenases [15], α-ketoglutarate/Fe2+-dependent halogenases [16], SAM-dependent halogenases [17][18], and vanadium-dependent

Microwave-assisted synthesis of 5,6-dihydroindolo[1,2-a]quinoxaline derivatives through copper-catalyzed intramolecular N-arylation

• Fei Zhao,
• Lei Zhang,
• Hailong Liu,
• Shengbin Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2013, 9, 2463–2469, doi:10.3762/bjoc.9.285

• system of CuI/L-proline/K2CO3 in DMSO under microwave irradiation for 45 minutes. After determining the optimal reaction conditions, we then examined the general applicability of the process. First, the substituents of the indole moiety were explored (Table 2). Halogens (F, Cl, Br) were tolerated well

Gold(I)-catalyzed hydroarylation reaction of aryl (3-iodoprop-2-yn-1-yl) ethers: synthesis of 3-iodo-2H-chromene derivatives

• Pablo Morán-Poladura,
• Eduardo Rubio and
• José M. González

Beilstein J. Org. Chem. 2013, 9, 2120–2128, doi:10.3762/bjoc.9.249

• electron-withdrawing substituents such as halogens an increase in selectivity was noticed as function of their number and nature. This is shown for the cyclization of 1a (Table 1, entry 7) in comparison with the cyclization of 1f and 1i (Table 2, entries 5 and 8). These results nicely match the proposed

An easy direct arylation of 5-pyrazolones

• Hao Gong,
• Yiwen Yang,
• Zechao Wang and
• Chunxiang Kuang

Beilstein J. Org. Chem. 2013, 9, 2033–2039, doi:10.3762/bjoc.9.240

• the other hand, when pyrazolones 1 carried an electron-withdrawing substituent such as nitro (1f) and halogens (1g, 1i and 1k) in the aromatic portion, relatively low yields were obtained (Table 3, entries 5, 6, 8, 10). Compared with 5-pyrazolones containing a butyl or a phenyl substituent on the 3

Practical synthesis of indoles and benzofurans in water using a heterogeneous bimetallic catalyst

• Cybille Rossy,
• Eric Fouquet and
• François-Xavier Felpin

Beilstein J. Org. Chem. 2013, 9, 1426–1431, doi:10.3762/bjoc.9.160

• , 22). For instance, the reaction was remarkably selective toward the iodine atom, leaving other halogens (Cl and Br) unaffected. Moreover, 3-iodo-2-aminopyridines 19 and 20 were remarkably reactive, giving the corresponding azaindoles 23 and 24 with excellent yields. On the other hand, aliphatic

• alkynes gave lower but still synthetically useful yields, even in the presence of halogens and free alcohols. Interestingly, indole 9 was obtained with an improved yield of 89% versus 68% when the corresponding 2-bromoaniline was used instead of the 2-iodoaniline 13. However, this trend was not observed

α-Bromodiazoacetamides – a new class of diazo compounds for catalyst-free, ambient temperature intramolecular C–H insertion reactions

• Åsmund Kaupang and
• Tore Bonge-Hansen

Beilstein J. Org. Chem. 2013, 9, 1407–1413, doi:10.3762/bjoc.9.157

• leaves the diazo function intact [4]. Among the reported transformations are substitutions of the diazomethyl hydrogen for electrophiles based on boron [5][6][7], nitrogen (NO2+) [8][9][10][11][12], silicon [13][14][15], phosphorous [16][17][18], sulfur [19][20][21] and halogens [10][22][23][24][25][26

• favoured by a less reactive carbenoid. This result may provide insight into why the formation of the bicyclic system is achieved starting from the α-bromodiazoacetamide 4c, but not from the α-H diazoacetamide 3c [61] (see Discussion on the carbene-stabilising effect of halogens below) employing an

Conformational analysis and intramolecular interactions in monosubstituted phenylboranes and phenylboronic acids

• Josué M. Silla,
• Rodrigo A. Cormanich,
• Roberto Rittner and
• Matheus P. Freitas

Beilstein J. Org. Chem. 2013, 9, 1127–1134, doi:10.3762/bjoc.9.125

• ability of halogens to participate in hydrogen bonds forming four- and five-membered rings. However, 6a, 7a and 8a, the most stable conformers for the respective compounds, exhibit dihydrogen bonds, with electronic densities ρ(r) superior to that found for 1b. Moreover, nX→π*CC interactions are also

• electron donors than halogens in these cases. This interaction is explicitly expressed for 8b and 9c by means of X∙∙∙B bond paths in QTAIM (Figure 7). Indeed, the B–C–C(N) bond angle in 8c and 9c is significantly curved to allow the formation of a four-membered ring, reflecting the effectiveness of the X/B

Use of 3-[¹⁸F]fluoropropanesulfonyl chloride as a prosthetic agent for the radiolabelling of amines: Investigation of precursor molecules, labelling conditions and enzymatic stability of the corresponding sulfonamides

• Reik Löser,
• Steffen Fischer,
• Achim Hiller,
• Martin Köckerling,
• Uta Funke,
• Aurélie Maisonial,
• Peter Brust and
• Jörg Steinbach

Beilstein J. Org. Chem. 2013, 9, 1002–1011, doi:10.3762/bjoc.9.115

• with [18F]fluoride, an alternative procedure to afford 3 was envisaged. Esters of sulfonic acids can be also prepared by nucleophilic displacement of carbon-bound halogens with sulfonates, which works best with alkyl iodides and silver salts of sulfonic acids [23]. Therefore, the required 3-iodopropyl

Polar reactions of acyclic conjugated bisallenes

• Reiner Stamm and
• Henning Hopf

Beilstein J. Org. Chem. 2013, 9, 36–48, doi:10.3762/bjoc.9.5

• is known about the behavior of noncyclic, conjugated bisallenes in ionic or polar reactions, whether these involve metalation processes, the addition of halogens and hydrogen halides, or oxidation reactions, to name but a few. To fill this gap we initiated a research program, hoping also that polar

• postulate a butadienylallene intermediate, 51, again. Halogenation of 2, 3 and 11 Among the addition of halogens the addition of bromine and iodine to various allenes has been particularly well studied [28]. Whereas bromine is added to the more highly substituted double bond of simple monoallenes, iodine

Computational evidence for intramolecular hydrogen bonding and nonbonding X···O interactions in 2'-haloflavonols

• Tânia A. O. Fonseca,
• Matheus P. Freitas,
• Rodrigo A. Cormanich,
• Teodorico C. Ramalho,
• Cláudio F. Tormena and
• Roberto Rittner

Beilstein J. Org. Chem. 2012, 8, 112–117, doi:10.3762/bjoc.8.12

• [2]. Moreover, intramolecular HB has been found to govern the conformational preference of molecules [3]. Intramolecular HB involving halogens (X) is less common than those involving oxygen or nitrogen as proton acceptors, while fluorine when bonded to carbon hardly ever participates in HB [4]. Even

• torsional angles in degrees, and C–X distance in angstroms), and selected NBO electron delocalization (kcal mol−1) for 2'-haloflavonols. QTAIM parametersa (a.u.) and O/F/C···H/X distanceb (Å) obtained for selected interacting atoms. QTAIM parameters (a.u.) for the hydrogen involved in HB and the halogens

Development of the titanium–TADDOLate-catalyzed asymmetric fluorination of β-ketoesters

• Lukas Hintermann,
• Mauro Perseghini and
• Antonio Togni

Beilstein J. Org. Chem. 2011, 7, 1421–1435, doi:10.3762/bjoc.7.166

• substrate range of the catalytic fluorination and its extension to other activated carbonyl compounds [57]. Results and Discussion Lewis acid catalyzed halogenation of activated carbonyl compounds Overview Nonfunctionalized ketones are halogenated in the α-position by halogens and other electrophilic

Combined directed ortho-zincation and palladium-catalyzed strategies: Synthesis of 4,n-dimethoxy-substituted benzo[b]furans

• Verónica Guilarte,
• M. Pilar Castroviejo,
• Estela Álvarez and
• Roberto Sanz

Beilstein J. Org. Chem. 2011, 7, 1255–1260, doi:10.3762/bjoc.7.146

• superbases and introduced by Schlosser [7]), as well as lithium dialkylamides, have usually been employed to perform deprotonative metallations. Whereas the use of these strong bases has several limitations regarding the presence of certain functional groups (mainly carboxylic acid derivatives and halogens

Recent advances in the gold-catalyzed additions to C–C multiple bonds

• He Huang,
• Yu Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2011, 7, 897–936, doi:10.3762/bjoc.7.103

• . reported a general gold-catalyzed direct oxidative homo-coupling of non-activated arenes 207 (Scheme 38). The reaction protocol tolerates a wide range of functional groups [92]. All halogens survive the reaction, which provides the potential for further reactions. 4.2 Rearrangements and ring enlargement A