Synthesis of fluoro-functionalized diaryl-λ³-iodonium salts and their cytotoxicity against human lymphoma U937 cells

• Prajwalita Das,
• Etsuko Tokunaga,
• Hidehiko Akiyama,
• Hiroki Doi,
• Norimichi Saito and
• Norio Shibata

Beilstein J. Org. Chem. 2018, 14, 364–372, doi:10.3762/bjoc.14.24

• , Toyoake, 470-1192, Japan Pharmaceutical Division, Ube Industries, Ltd. Seavans North Bldg., 1-2-1 Shibaura, Minato-ku, Tokyo 105-8449, Japan Institute of Advanced Fluorine-Containing Materials, Zhejiang Normal University, 688 Yingbin Avenue, 321004 Jinhua, China 10.3762/bjoc.14.24 Abstract Conscious of

• the potential bioactivity of fluorine, an investigation was conducted using various fluorine-containing diaryliodonium salts in order to study and compare their biological activity against human lymphoma U937 cells. Most of the compounds tested are well-known reagents for fluoro-functionalized

• )phenyl)iodonium exhibited the greatest potency in vitro against U937 cells. Evaluation of the cytotoxicity of selected phenylaryl-λ3-iodonium salts against AGLCL (a normal human B cell line) was also examined. Keywords: biological activity; diaryliodonium salt; fluorine; hypervalent iodine; lymphoma

Nucleophilic fluoroalkylation/cyclization route to fluorinated phthalides

• Masanori Inaba,
• Tatsuya Sakai,
• Shun Shinada,
• Tsuyuka Sugiishi,
• Yuta Nishina,
• Norio Shibata and
• Hideki Amii

Beilstein J. Org. Chem. 2018, 14, 182–186, doi:10.3762/bjoc.14.12

• good yields. Keywords: cyclization; fluorine; lactone; phthalide; trifluoromethylation; Introduction Phthalides (1(3H)-isobenzofuranones) are frequently found in natural products and exhibit a range of bioactivity (Scheme 1) [1][2]. Substituted phthalides have been used as building blocks for the

• [3][4][5][6][7][8][9][10]. Selective incorporation of fluorine or a fluoroalkyl group into a molecule is a topic of significant interest in organic chemistry. Fluorinated phthalides are considered to be one of the most fascinating organofluorine compounds. However, to our best knowledge, there have

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

• trifluoromethyl groups into organic molecules has attracted great attention in the past five years. In this review, we describe the recent efforts in the development of trifluoromethylation via copper catalysis using nucleophilic, electrophilic or radical trifluoromethylation reagents. Keywords: copper; fluorine

• ; trifluoromethylation; Introduction The fluorine atom has a strong electronegativity and a small atomic radius, and the incorporation of fluoroalkyl groups into molecules imparts a variety of features. The trifluoromethyl group, as the most significant common used fluoroalkyl group, could improve molecular properties

Gram-scale preparation of negative-type liquid crystals with a CF₂CF₂-carbocycle unit via an improved short-step synthetic protocol

• Tatsuya Kumon,
• Shohei Hashishita,
• Takumi Kida,
• Shigeyuki Yamada,
• Takashi Ishihara and
• Tsutomu Konno

Beilstein J. Org. Chem. 2018, 14, 148–154, doi:10.3762/bjoc.14.10

• ; tetrafluorinated cyclohexadiene; tetrafluorinated cyclohexane; Introduction Fluorine-containing organic compounds have attracted much attention in various areas, such as the medicinal, agrochemical, and materials science fields [1][2][3], due to the unique characteristics of the fluorine atom [4][5][6]. It is

• well known that fluorine atoms incorporated into organic substances very often lead to intriguing physical as well as chemical properties. Therefore, considerable attention has been devoted to the development of efficient synthetic protocols for fluorine-containing organic compounds. Owing to the

• fascinating molecular properties of organofluorine compounds exerted by the fluorine atom, our research group has devoted sustained effort to the development of novel biologically active fluorinated substances and high-functional fluorinated materials thus far [7][8][9]. Our recent interest inspired by 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

• C–F amination reactions employing water/isopropanol [3] and triols [4][5] as hydrogen-bond donor activators. Through these studies, the authors suggested that multiple donors (even when using a triol) surround the fluorine atom of the benzyl fluoride, thus stabilising the transition state through

• mechanisms operating in these Friedel–Crafts reactions as shown in Figure 4. (A) Coordination of the fluorine atom with the hydrogen bond donor, followed by backside attack of the nucleophile leads to SN2 reaction and inversion of configuration. (B) Hydrogen bond donor coordination to fluorine leads to

Microfluidic radiosynthesis of [¹⁸F]FEMPT, a high affinity PET radiotracer for imaging serotonin receptors

• Thomas Lee Collier,
• Steven H. Liang,
• J. John Mann,
• Neil Vasdev and
• J. S. Dileep Kumar

Beilstein J. Org. Chem. 2017, 13, 2922–2927, doi:10.3762/bjoc.13.285

• Psychiatric Institute, New York, NY, USA 10.3762/bjoc.13.285 Abstract Continuous-flow microfluidics has shown increased applications in radiochemistry over the last decade, particularly for both pre-clinical and clinical production of fluorine-18 labeled radiotracers. The main advantages of microfluidics are

• receptor, [18F]FEMPT (pKi = 9. 79; Ki = 0.16 nM) by microfluidic radiochemistry. [18F]FEMPT was obtained in ≈7% isolated radiochemical yield and in >98% radiochemical and chemical purity. The molar activity of the final product was determined to be >148 GBq/µmol (>4 Ci/µmol). Keywords: agonist; fluorine

• agreement with the known distribution of the 5-HT1AR. Despite the excellent binding profile of [11C]MPT, the slow washout in baboons limits this radiotracer from advancing to human studies. Our recent efforts have focused on the development of fluorine-18 (t½ = 109.7 min) labelled MPT derivatives, as the

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

• Graham Pattison Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK 10.3762/bjoc.13.284 Abstract Fluorine has been shown in many cases to impart specific and predictable effects on molecular conformation. Here it is shown that these conformational effects may

• , fluorine is often involved in introducing unusual properties to organic molecules, whether by its strong inductive effect, interactions of its tightly-held lone pairs or through the strong dipole moment it can induce in molecules [7]. To begin to quantify the effects of α-halogenation on carbonyl

• observed) (Scheme 2). Potential reasons behind the lower than expected reactivity of α-fluoroacetophenone were then considered. It is known that fluorine can dramatically influence the conformational preferences of molecules [8][9], so began by simulating the conformational energy profile of each α

Halogen-containing thiazole orange analogues – new fluorogenic DNA stains

• Aleksey A. Vasilev,
• Meglena I. Kandinska,
• Stanimir S. Stoyanov,
• Stanislava B. Yordanova,
• David Sucunza,
• Juan J. Vaquero,
• Obis D. Castaño,
• Stanislav Baluschev and
• Silvia E. Angelova

Beilstein J. Org. Chem. 2017, 13, 2902–2914, doi:10.3762/bjoc.13.283

• spectra and is in contrast to the by Armitage et al. observed influence of the replacement of hydrogen with fluorine atom in the benzothiazole ring [43]. Photostability The photostability of all dyes in the series was evaluated in acetonitrile with irradiation at 254 nm with a mercury lamp in equal

The synthesis of the 2,3-difluorobutan-1,4-diol diastereomers

• Robert Szpera,
• Nadia Kovalenko,
• Kalaiselvi Natarajan,
• Nina Paillard and
• Bruno Linclau

Beilstein J. Org. Chem. 2017, 13, 2883–2887, doi:10.3762/bjoc.13.280

• Robert Szpera Nadia Kovalenko Kalaiselvi Natarajan Nina Paillard Bruno Linclau Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, United Kingdom 10.3762/bjoc.13.280 Abstract The diastereoselective synthesis of fluorinated building blocks that contain chiral fluorine

• opening; fluorinated building block; vicinal difluoride; Introduction The introduction of fluorine in organic compounds usually results in the modification of a range of chemical, physical and biological properties [1]. Fluorine incorporation is therefore a common strategy to optimise the properties of

• drugs/agrochemicals, as well as materials [2][3][4][5][6]. Many methods exist for the stereoselective introduction of the C–F group [7][8][9][10][11]. An alternative and often time-efficient approach is the use of fluorinated building blocks, where fluorine is introduced as part of a carbon containing

Position-dependent impact of hexafluoroleucine and trifluoroisoleucine on protease digestion

• Susanne Huhmann,
• Anne-Katrin Stegemann,
• Kristin Folmert,
• Damian Klemczak,
• Johann Moschner,
• Michelle Kube and
• Beate Koksch

Beilstein J. Org. Chem. 2017, 13, 2869–2882, doi:10.3762/bjoc.13.279

• towards proteolysis by α-chymotrypsin, pepsin, proteinase K, and elastase was studied, and this process was followed by an FL-RP-HPLC assay in combination with mass spectrometry. In a few cases, we observed an exceptional increase in proteolytic stability upon introduction of the fluorine substituents

• , backbone-extended or chemically modified amino acids [1]. In this regard, the incorporation of fluorine into amino acids has become a promising strategy. Fluorine’s unique properties, namely low polarizability, a strong inductive effect, and high electronegativity, as well as its small size, result in

• observed that the introduction of fluorine atoms into the Abu side chain can significantly improve or dramatically reduce resistance to hydrolysis by different enzymes and human blood plasma, depending upon the fluorine content of the side chain, the position of the substitution relative to the cleavage

The use of 4,4,4-trifluorothreonine to stabilize extended peptide structures and mimic β-strands

• Yaochun Xu,
• Isabelle Correia,
• Tap Ha-Duong,
• Nadjib Kihal,
• Jean-Louis Soulier,
• Julia Kaffy,
• Benoît Crousse,
• Olivier Lequin and
• Sandrine Ongeri

Beilstein J. Org. Chem. 2017, 13, 2842–2853, doi:10.3762/bjoc.13.276

• CF3-threonine containing pentapeptides interact with the amyloid peptide Aβ1-42 in order to reduce the protein–protein interactions mediating its aggregation process. Keywords: aggregation; beta-sheet; fluorine; peptide; unnatural amino acid; Introduction It is estimated that 20% of administered

• drugs contain fluorine atoms or fluoroalkyl groups, representing 150 fluorinated molecules, and this trend is expected to increase to about 30% in the early future as a new generation of fluorinated compounds is currently in Phase II−III clinical trials [1]. In parallel, pharmaceutical peptides are

• that the presence of fluorine atoms probably increased the interaction of pentapeptides with Aβ1-42 and their inhibitory effect on Aβ1-42 aggregation. Conclusion We synthesized eight pentapeptides 1a–4a and 1b–4b having the sequence RHN-Ala-Val-X-Val-Leu-OMe, where the central residue X is L-serine, L

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

• that CF3SO2Cl reacts under reductive conditions while CF3SO2Na requires oxidative conditions. Electrophilic chlorination is obviously the exclusive preserve of CF3SO2Cl that has been exploited with emphasis in enantioselective chlorination. Keywords: chlorination; fluorine; sulfur

• l’Enseignement Supérieur” for a doctoral fellowship. H.G. thanks Normandy University for a postdoctoral grant. The French Fluorine Network (GIS Fluor) is also acknowledged.

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation. Part 1: Use of CF₃SO₂Na

• Hélène Guyon,
• Hélène Chachignon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2764–2799, doi:10.3762/bjoc.13.272

• reactions, the versatility of these two reagents is presented in other reactions such as sulfonylation and chlorination. This first part is dedicated to sodium trifluoromethanesulfinate. Keywords: fluorine; sulfur; trifluoromethylation; trifluoromethylsulfenylation; trifluoromethylsulfonylation

Ring-size-selective construction of fluorine-containing carbocycles via intramolecular iodoarylation of 1,1-difluoro-1-alkenes

• Takeshi Fujita,
• Ryo Kinoshita,
• Tsuyoshi Takanohashi,
• Naoto Suzuki and
• Junji Ichikawa

Beilstein J. Org. Chem. 2017, 13, 2682–2689, doi:10.3762/bjoc.13.266

• site-selective intramolecular iodoarylation by the appropriate cationic iodine species. Iodoarylation of 2-(2-aryl-3,3-difluoroallyl)biaryls proceeded via regioselective carbon–carbon bond formation at the carbon atoms in β-position to the fluorine substituents, thereby constructing dibenzo-fused six

• -membered carbocycles bearing a difluoroiodomethyl group. In contrast, 2-(3,3-difluoroallyl)biaryls underwent a similar cyclization at the α-carbon atoms to afford ring-difluorinated seven-membered carbocycles. Keywords: alkenes; carbocycles; cyclization; electrophilic activation; fluorine; iodine

• carbocycles that are promising candidates for pharmaceuticals, agrochemicals, and functional materials. In contrast, the cationic cyclization of 1,1-difluoro-1-alkenes using electrophilic reagents (under acidic conditions) has been quite limited because of their low electron densities caused by fluorine

Recent progress in the racemic and enantioselective synthesis of monofluoroalkene-based dipeptide isosteres

• Myriam Drouin and
• Jean-François Paquin

Beilstein J. Org. Chem. 2017, 13, 2637–2658, doi:10.3762/bjoc.13.262

• tertiary and quaternary structures. To have a good amide bond isostere, these different aspects should be reproduced, which is mostly the case with the monofluoroalkene moiety [8]. The monofluoroalkene is a rigid molecule as it possesses a double bond. Furthermore, the fluorine atom bears a partial

• negative charge, with a dipole moment of 1.4 D. Finally, the monofluoroalkene has the ability to accept a hydrogen bond through the fluorine atom [9]. Geometrically, the monofluoroalkene is quite similar to the amide bond. The C=O bond of the amide is 1.228 Å, compared to 1.376 Å for the C–F bond, and the

Electrophilic trifluoromethylselenolation of terminal alkynes with Se-(trifluoromethyl) 4-methylbenzenesulfonoselenoate

• Clément Ghiazza,
• Anis Tlili and
• Thierry Billard

Beilstein J. Org. Chem. 2017, 13, 2626–2630, doi:10.3762/bjoc.13.260

• Research for financial support. The French Fluorine Network is also acknowledged for its support. We thank Dr. Erwann Jeanneau (Centre de Diffractométrie Henri Longchambon) for collecting the crystallographic data and solving the structure of 3a.

Regioselective decarboxylative addition of malonic acid and its mono(thio)esters to 4-trifluoromethylpyrimidin-2(1H)-ones

• Sergii V. Melnykov,
• Andrii S. Pataman,
• Yurii V. Dmytriv,
• Svitlana V. Shishkina,
• Mykhailo V. Vovk and
• Volodymyr A. Sukach

Beilstein J. Org. Chem. 2017, 13, 2617–2625, doi:10.3762/bjoc.13.259

• modern drug discovery and development area [9][10]. As a result of intensive research efforts over the last decades, efficient fluorination and fluoroalkylation methods have emerged to prepare previously challenging molecules decorated with fluorine atoms or fluorinated groups which make them practically

• useful [11][12][13][14]. A building-block approach remains an alternative strategy to the synthesis of fluorine-containing compounds. This complementary method takes advantage of specific reagents featuring original fluorinated motives and/or functional groups which affords more complex derivatives via

Palladium-catalyzed Heck-type reaction of secondary trifluoromethylated alkyl bromides

• Tao Fan,
• Wei-Dong Meng and
• Xingang Zhang

Beilstein J. Org. Chem. 2017, 13, 2610–2616, doi:10.3762/bjoc.13.258

• applications of fluorinated compounds in life and materials science, developing efficient and straightforward methods for the synthesis of fluorinated compounds has become more and more important. Although great achievements have been made in the introduction of fluorine atom(s) into organic molecules over the

Diastereoselective Mannich reactions of pseudo-C₂-symmetric glutarimide with activated imines

• Tatsuya Ishikawa,
• Tomoko Kawasaki-Takasuka,
• Toshio Kubota and
• Takashi Yamazaki

Beilstein J. Org. Chem. 2017, 13, 2473–2477, doi:10.3762/bjoc.13.244

• . Crystallographic analysis of the major diastereomer of 3a (some hydrogen atoms are omitted for clarity). Each color represents the following atoms: gray, carbon; white, hydrogen; blue, nitrogen; red, oxygen; green, fluorine; yellow, sulfur. Explanation of the construction of the main stereoisomers. Optimization of

Hydrolysis, polarity, and conformational impact of C-terminal partially fluorinated ethyl esters in peptide models

• Vladimir Kubyshkin and
• Nediljko Budisa

Beilstein J. Org. Chem. 2017, 13, 2442–2457, doi:10.3762/bjoc.13.241

• nucleus. Fluorination of molecular scaffolds can also selectively influence a molecule’s polarity, conformational preferences and chemical reactivity, properties that can be exploited for various chemical applications. A powerful route for incorporating fluorine atoms in biomolecules is last-stage

• undergo variable hydrolysis in biologically relevant buffers. The hydrolytic stability can be tailored over a broad pH range by varying the number of fluorine atoms in the ester moiety or by introducing adjacent charges in the peptide sequence. Keywords: conformation; ester bond; hydrolysis; peptides

• ; polarity; Introduction Fluorine is a rare element in natural biochemical settings [1]. Notwithstanding several prominent fluoro-organic metabolites in nature [2][3], fluorine is virtually absent from natural biopolymers such as proteins and nucleic acids. Therefore, organofluorine groups lack a natural

Fluorination of some highly functionalized cycloalkanes: chemoselectivity and substrate dependence

• Attila Márió Remete,
• Melinda Nonn,
• Santos Fustero,
• Matti Haukka,
• Ferenc Fülöp and
• Loránd Kiss

Beilstein J. Org. Chem. 2017, 13, 2364–2371, doi:10.3762/bjoc.13.233

• -amino ester stereo- and regioisomers, derived from unsaturated cyclic β-amino acids is described. The nucleophilic fluorinations involving hydroxy–fluorine exchange of some highly functionalized alicyclic diol derivatives have been carried out in view of selective fluorination, investigating substrate

• dependence, neighboring group assistance and chemodifferentiation. Keywords: amino acids; chemoselectivity; fluorine; functionalization; stereoisomers; Introduction Fluorinated molecules exert an ever-increasing impact in medicinal chemistry thanks to their valuable biological properties. Numerous drugs

• introduced to the market nowadays contain fluorine, and their number is expected to continuously increase in years to come [1][2]. Therefore, there is a high demand in synthetic organic and medicinal chemistry for both, the synthesis of novel fluorinated biomolecules and the development of selective and

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

• based on F2 using SHELXL–2016 [60] integrated in the WinGX program package [61]. All hydrogen atoms were included in calculated positions, with SHELXL–2016 defaults. Fluorine atoms of trifloromethyl groups in 5–8 were disordered and have been refined with fixed occupancy ratio of 0.60/0.40 in 5 and 8

• , 0.70/0.30 in 6, and 0.68/0.32 in 7. Geometric restraint on some of the C–F distances and restraint on anisotropic displacement parameters of some fluorine atoms in 5–8 were applied in the refinement. The PLATON [62] and Mercury [63] programs were used for structure analysis and molecular and crystal

• the atom-numbering scheme. Displacement ellipsoids for non-hydrogen atoms are drawn at the 30% probability level. Only the major component of disordered fluorine atoms is presented. (b) Overlap of molecules 5–8 showing almost identical molecular conformation. Color code: 5 green, 6 orange, 7 purple, 8

Homologated amino acids with three vicinal fluorines positioned along the backbone: development of a stereoselective synthesis

• Raju Cheerlavancha,
• Ahmed Ahmed,
• Yun Cheuk Leung,
• Aggie Lawer,
• Qing-Quan Liu,
• Marina Cagnes,
• Hee-Chan Jang,
• Xiang-Guo Hu and
• Luke Hunter

Beilstein J. Org. Chem. 2017, 13, 2316–2325, doi:10.3762/bjoc.13.228

• diastereoisomers of this fluorinated δ-amino acid adopt distinct conformations in solution, suggesting that these molecules might have value as shape-controlled building blocks for future applications in peptide science. Keywords: amino acids; conformation; deoxyfluorination; fluorine; stereochemistry

• amino acid unit in a natural peptide without changing the overall length of the peptide [16]. The presence of three vicinal fluorine atoms on the amino acid backbone of 6 gives rise to eight possible stereoisomeric forms, which presents a synthetic challenge of stereocontrol. As an initial contribution

• stereoisomer. Then, if the carbon chain of 8 could be extended by one atom to give the homologated aldehyde 9, fluorination could be repeated and the cycle could continue until the desired number of fluorine atoms was installed. This hypothetical approach had several attractions, including (i) the flexibility

Comparative profiling of well-defined copper reagents and precursors for the trifluoromethylation of aryl iodides

• Peter T. Kaplan,
• Jessica A. Lloyd,
• Mason T. Chin and
• David A. Vicic

Beilstein J. Org. Chem. 2017, 13, 2297–2303, doi:10.3762/bjoc.13.225

• employed directly or generated in situ from precursors by published reports. Relative reactivities were also found to highly dependent on the nature of the iodoarenes. Keywords: benchmarking; copper; fluorine; fluoroalkylation; trifluoromethylation; Introduction Selectively fluorinated molecules that

• as the major fluorine-containing product. Because our group has developed the NHC-based copper reagents for trifluoromethylation reactions [10][11], we were interested in comparing the effects of electronics and sterics of the aryl halides using the NHC-based systems A1 and A2 with the phen system B2

Synthesis and application of trifluoroethoxy-substituted phthalocyanines and subphthalocyanines

• Satoru Mori and
• Norio Shibata

Beilstein J. Org. Chem. 2017, 13, 2273–2296, doi:10.3762/bjoc.13.224

• by the strong electronegativity of fluorine. Therefore, it is expected that trifluoroethoxy-substituted phthalocyanines can be applied to new industrial fields. This review summarizes the synthesis and application of trifluoroethoxy-substituted phthalocyanine and subphthalocyanine derivatives

• . Keywords: aggregation; fluorine; phthalocyanine; subphthalocyanine; trifluoroethoxy; Introduction Phthalocyanines [1][2][3] are analogues of porphyrin condensed with four isoindoline units via a nitrogen atom and exhibit a deep blue color due to their wide 18π electron conjugation. Among them, the most

• treatment method [17] and other applications. Incidentally, fluorine is one of the elements that is expected to improve the state-of-the-art science technology [18]. Fluorine is located at the top right of the periodic table of elements excluding the noble gas elements of group 18. The size of fluorine is