Electrochemically modified Corey–Fuchs reaction for the synthesis of arylalkynes. The case of 2-(2,2-dibromovinyl)naphthalene

• Fabiana Pandolfi,
• Isabella Chiarotto and
• Marta Feroci

Beilstein J. Org. Chem. 2018, 14, 891–899, doi:10.3762/bjoc.14.76

• reagents and frequently these reactions are carried out at room temperature and at atmospheric pressure, etc. [16][17][18][19]. The electrochemical behavior of halogenated compounds has been extensively investigated [20][21][22]. The cleavage of the C–halogen bond, yielding (via a radical intermediate) the

• corresponding carbanion and halogen anion, can be achieved by a bielectronic cathodic process (Scheme 2). The electrolysis is carried out at a suitable controlled potential, i.e., at a potential that is negative enough to achieve the selective fission of the envisaged C–halogen bond [23]. Therefore, the

• = 25 °C; solvent left: DMF/Et4NBF4 0.1 mol dm−3; right: ACN/Et4NBF4 0.1 mol dm−3. Variation of the amounts of 1a, 2a, and 3a with the number of Faradays of 1a. The Corey–Fuchs reaction. Electrochemical reduction of a carbon–halogen bond. Electrochemical synthesis of vinyl bromides [25]. Scope of this

Progress in copper-catalyzed trifluoromethylation

• Guan-bao Li,
• Chao Zhang,
• Chun Song and
• Yu-dao Ma

Beilstein J. Org. Chem. 2018, 14, 155–181, doi:10.3762/bjoc.14.11

• allylic halides were also subjected to these conditions. It is notable that the trifluoromethyl group was introduced at the α position of the carbon–halogen bond with complete regioselectivity. Later, they extended these conditions to propargylic halides [27] and succeeded in synthesizing the

Stereochemical outcomes of C–F activation reactions of benzyl fluoride

• Neil S. Keddie,
• Pier Alexandre Champagne,
• Justine Desroches,
• Jean-François Paquin and
• David O'Hagan

Beilstein J. Org. Chem. 2018, 14, 106–113, doi:10.3762/bjoc.14.6

• carbon–halogen bond known [1]. Its low reactivity, in comparison to other C–X bonds, means that it is inert to all but the most harsh reaction conditions, and fluorine can generally be carried through multistep syntheses without concern over side reactions (the exception being SNAr reactions). In recent

Conformational preferences of α-fluoroketones may influence their reactivity

• Graham Pattison

Beilstein J. Org. Chem. 2017, 13, 2915–2921, doi:10.3762/bjoc.13.284

• -haloacetophenone, calculating the energy of each compound as the carbon–halogen bond is rotated through 10° increments in both the gas phase and in ethanol as reaction solvent (Figure 1) [10]. The fluorinated acetophenone showed significant differences in conformational energy to the chlorinated and brominated

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation and chlorination. Part 2: Use of CF₃SO₂Cl

• Hélène Chachignon,
• Hélène Guyon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2800–2818, doi:10.3762/bjoc.13.273

• of an halogen bond between the positive electrostatic potential on the outer side of the chlorine atom and the lone pair of the phosphorus atom of the phosphine. This phenomenon indeed triggered the cleavage of the S–Cl bond, producing chlorophosphonium sulfinate 40, which was then readily converted

Pyrene–nucleobase conjugates: synthesis, oligonucleotide binding and confocal bioimaging studies

• Artur Jabłoński,
• Yannic Fritz,
• Hans-Achim Wagenknecht,
• Rafał Czerwieniec,
• Tytus Bernaś,
• Damian Trzybiński,
• Krzysztof Woźniak and
• Konrad Kowalski

Beilstein J. Org. Chem. 2017, 13, 2521–2534, doi:10.3762/bjoc.13.249

• observed in the molecular structures of the metallocene–nucleobase derivatives [24][29]. In addition, each molecule of 2 in the dimer is further involved in a Cl···O halogen bond with an adjacent molecule of chloroform (Figure 3). Further details of intermolecular interactions present in the crystal

Solvent-free copper-catalyzed click chemistry for the synthesis of N-heterocyclic hybrids based on quinoline and 1,2,3-triazole

• Martina Tireli,
• Silvija Maračić,
• Stipe Lukin,
• Marina Juribašić Kulcsár,
• Dijana Žilić,
• Mario Cetina,
• Ivan Halasz,
• Silvana Raić-Malić and
• Krunoslav Užarević

Beilstein J. Org. Chem. 2017, 13, 2352–2363, doi:10.3762/bjoc.13.232

• bands at 1099 (Cl), 1077 (Br) and 1064 (I) cm−1 which are assigned to vibration of the phenyl ring that contains the carbon–halogen bond. Characteristic C≡C alkyne band at 2133 cm−1 along with the band at 1258 cm−1 of the triazole products are appropriate for monitoring of the reaction progress. In situ

Detection of therapeutic radiation in three-dimensions

• John A. Adamovics

Beilstein J. Org. Chem. 2017, 13, 1325–1331, doi:10.3762/bjoc.13.129

• consistent with the bond energy of the carbon–halogen bond. The observed sensitivity was in the order R3C–I > R3C–Br > R3C–Cl [42][43][44]. Due to the high electron density of radical initiators containing iodine even at relatively low concentrations (100 mM) result in dosimeters that are not tissue

New approaches to organocatalysis based on C–H and C–X bonding for electrophilic substrate activation

• Pavel Nagorny and
• Zhankui Sun

Beilstein J. Org. Chem. 2016, 12, 2834–2848, doi:10.3762/bjoc.12.283

• organic catalysts for electrophile activation through the formation of C–H hydrogen bonds and C–X halogen bonds. Keywords: C–H hydrogen bond; counteranion activation; electrophile activation; halogen bond donor; hydrogen bond donor; organocatalysis; Review Introduction Over the past century chemists

• form stable adducts with neutral and charged Lewis bases, and to account for this IUPAC provided the following recommendation “A halogen bond occurs when there is evidence of a net attractive interaction between an electrophilic region associated with a halogen atom in a molecular entity and a

• and are critical for the resolution. This example clearly demonstrate the great potential of halogen bonds as tools for asymmetric catalysis. Early uses of halogen bond donors in catalysis and organocatalysis Like hydrogen bonds, halogen bonds possess important features such as strength and

Trifluoromethyl-substituted tetrathiafulvalenes

• Olivier Jeannin,
• Frédéric Barrière and
• Marc Fourmigué

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

• accordingly, several tetrathiafulvalenes bearing only one or two ester [10], nitrile [11][12][13][14], amide [7][15][16][17], thioamide [18][19][20], or halogen [5] substituents were successfully engaged in radical cation salts by electrocrystallization, with intermolecular hydrogen [21][22][23] of halogen

• bond interactions [24][25][26][27]. Within such TTF derivatives, as reported by Bryce [28], an internal charge transfer (ICT) between the TTF and the EWG moieties increases the hydrophilicity of the TTF head groups and facilitates monolayer formation on the water surface for the preparation of Langmuir

Palladium-catalyzed dual C–H or N–H functionalization of unfunctionalized indole derivatives with alkenes and arenes

• Gianluigi Broggini,
• Egle M. Beccalli,
• Andrea Fasana and
• Silvia Gazzola

Beilstein J. Org. Chem. 2012, 8, 1730–1746, doi:10.3762/bjoc.8.198

• moderate yields, this strategy constitutes an alternative choice to the palladium-catalyzed cyclization of indole amides bearing a carbon–halogen bond to give medium and large ring-fused indoles [72]. Although a stoichiometric amount of Pd(OAc)2 is needed, intramolecular alkenylations of suitable 3

Kinetic evaluation of the solvolysis of isobutyl chloro- and chlorothioformate esters

• Malcolm J. D’Souza,
• Matthew J. McAneny,
• Dennis N. Kevill,
• Jin Burm Kyong and
• Song Hee Choi

Beilstein J. Org. Chem. 2011, 7, 543–552, doi:10.3762/bjoc.7.62

• to the chlorocarbonyl group in alkyl chloro- and chlorothioformates, the positive entropies and low solvent isotope effects pointed to a mechanism involving a unimolecular acyl–halogen bond fission. More recent studies on alkyl and aryl chlorothio-, chlorodithio-, and chlorothionoformate esters favor

The subtle balance of weak supramolecular interactions: The hierarchy of halogen and hydrogen bonds in haloanilinium and halopyridinium salts

• Kari Raatikainen,
• Massimo Cametti and
• Kari Rissanen

Beilstein J. Org. Chem. 2010, 6, No. 4, doi:10.3762/bjoc.6.4

• systems and its potential in drug development has also been recognized [22]. The halogen bond (XB), whose terminology emphasizes the similarity with hydrogen bonding [23] can be schematically described by Y–X···A, where X is the XB donor atom (Lewis acid, electrophilic) and A is the XB acceptor atom

• ], following the polarizability of halogen atom. The hybridization of the C–X carbon atom on the XB donor molecule has also an effect on the strength and directionality of the halogen bond. The order C(sp3) < C(sp2) < C(sp) is generally followed [24][25][26] and for example haloalkynes are found to be

• particularly good halogen bond donors [27][28]. As seen in PFC compounds, electron withdrawing moieties present on the Y group favor the interaction. For this reason haloarenes where the aromatic ring has electron withdrawing substituents e.g. fluorines [11][12][13][14][15][16][18][19] are also excellent