Clickable azide-functionalized bromoarylaldehydes – synthesis and photophysical characterization

• Dominik Göbel,
• Marius Friedrich,
• Enno Lork and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2020, 16, 1683–1692, doi:10.3762/bjoc.16.139

• are highly desirable [16][17][34][35][36][37]. Two approaches are applied to achieve organic phosphors: (1) introduction of nonmetal heavy atoms, such as halogens (Br or I) or functionalities containing lone pairs, in particular carbonyl groups, nitrogen, sulfur, and phosphorus derivatives which

Models of necessity

• Timothy Clark and
• Martin G. Hicks

Beilstein J. Org. Chem. 2020, 16, 1649–1661, doi:10.3762/bjoc.16.137

• interaction between halogens and nucleophiles as repulsive; whereas we now know that halogen-bonding attractions can be as strong as hydrogen bonds. There will be more such examples but it is important to identify the encompassing phenomenon, rather than defining a wealth of apparently unique interactions

Distinctive reactivity of N-benzylidene-[1,1'-biphenyl]-2-amines under photoredox conditions

• Shrikant D. Tambe,
• Kwan Hong Min,
• Naeem Iqbal and
• Eun Jin Cho

Beilstein J. Org. Chem. 2020, 16, 1335–1342, doi:10.3762/bjoc.16.114

• ), ethers (2e), halogens (2i and 2l) [48][49][50], the medicinally important CF3 group (2m), and acetals (2p) were tolerated under these mild reaction conditions. The substitution pattern of the aryl groups, such as ortho (2c, 2e, and 2k), meta (2m and 2p), and para substitution (2b–2d, 2g, 2i, 2l, 2o, and

Copper-based fluorinated reagents for the synthesis of CF₂R-containing molecules (R ≠ F)

• Louise Ruyet and
• Tatiana Besset

Beilstein J. Org. Chem. 2020, 16, 1051–1065, doi:10.3762/bjoc.16.92

• that the PhSO2CF2Cu species might be prepared from difluoromethylphenylsulfone (PhSO2CF2H) and used it to functionalize an array of (hetero)aromatic boronic acids [62] (Scheme 12). The transformation showed a good functional group tolerance (aldehyde, CN, halogens). Note that the synthetic utility of

Rhodium-catalyzed reductive carbonylation of aryl iodides to arylaldehydes with syngas

• Zhenghui Liu,
• Peng Wang,
• Zhenzhong Yan,
• Suqing Chen,
• Dongkun Yu,
• Xinhui Zhao and
• Tiancheng Mu

Beilstein J. Org. Chem. 2020, 16, 645–656, doi:10.3762/bjoc.16.61

• halogens to arylaldehydes have been developed. The homogeneous systems included Pd(OAc)2 with propyl di-tert-butylphosphinite ligand [30], Pd(acac)2 with dppm ligand [31], Pd(OAc)2 with CataCXium A ligand [32], and all of the three systems employed TMEDA as the base and toluene as the solvent. The

Architecture and synthesis of P,N-heterocyclic phosphine ligands

• Wisdom A. Munzeiwa,
• Bernard Omondi and
• Vincent O. Nyamori

Beilstein J. Org. Chem. 2020, 16, 362–383, doi:10.3762/bjoc.16.35

• Preparation of N-heterocyclic phosphines via P–C bond formation Nucleophilic substitution of halogens There are different methods that have been reported for the construction of the P–C bonds. Two approaches are possible using halogenated precursors. The first one is the organometal-halogen-phosphine route

Efficient method for propargylation of aldehydes promoted by allenylboron compounds under microwave irradiation

• Jucleiton J. R. Freitas,
• Queila P. S. B. Freitas,
• Silvia R. C. P. Andrade,
• Juliano C. R. Freitas,
• Roberta A. Oliveira and
• Paulo H. Menezes

Beilstein J. Org. Chem. 2020, 16, 168–174, doi:10.3762/bjoc.16.19

• interesting to note that the nitro group remained intact under the reaction conditions. Usually, this group is sensitive to reduction when alternative methods involving zinc or tin are used [33]. In addition, aldehydes containing halogens also gave the corresponding products 2j–l in moderate yields. These

Chemical synthesis of tripeptide thioesters for the biotechnological incorporation into the myxobacterial secondary metabolite argyrin via mutasynthesis

• David C. B. Siebert,
• Roman Sommer,
• Domen Pogorevc,
• Michael Hoffmann,
• Silke C. Wenzel,
• Rolf Müller and
• Alexander Titz

Beilstein J. Org. Chem. 2019, 15, 2922–2929, doi:10.3762/bjoc.15.286

• ’-methoxy group to halogens or other substituents in different positions led to a loss of antibacterial activity, whereas the 5’-methoxytryptophan regioisomer largely retained activity against P. aeruginosa PAO1. Inspection of the crystal structure of argyrin in complex with the bacterial elongation factor

Acid-catalyzed rearrangements in arenes: interconversions in the quaterphenyl series

• Sarah L. Skraba-Joiner,
• Carter J. Holt and
• Richard P. Johnson

Beilstein J. Org. Chem. 2019, 15, 2655–2663, doi:10.3762/bjoc.15.258

• arenium ions, like many other types of carbocations, often rearrange by 1,2-shifts. This leads to a fascinating collection of rearrangements that can migrate hydrogen, halogens or more complex substituents around the ring and even modify the carbon skeleton. Early reports by Baddeley [18] helped to

Synthesis of a dihalogenated pyridinyl silicon rhodamine for mitochondrial imaging by a halogen dance rearrangement

• Jessica Matthias,
• Thines Kanagasundaram,
• Klaus Kopka and
• Carsten S. Kramer

Beilstein J. Org. Chem. 2019, 15, 2333–2343, doi:10.3762/bjoc.15.226

• explained with rotation restriction around the pyridinyl–xanthene bond and/or with beneficial effects of the halogens on the HOMO energy level. Nevertheless, the pyridinyl SiR 14 performs better due to the addition contributions of the azetidine rings. Next, we examined the targeting ability to mitochondria

• experiments (supported by DFT calculations) on the orbital effects of both halogens and the nitrogen position in the pyridine ring are needed to explain these effects with confidence. In addition, our SiR dye 15 displays photophysical properties (extinction coefficient, quantum yield, lifetime) in the same

Recent advances in transition-metal-catalyzed incorporation of fluorine-containing groups

• Xiaowei Li,
• Xiaolin Shi,
• Xiangqian Li and
• Dayong Shi

Beilstein J. Org. Chem. 2019, 15, 2213–2270, doi:10.3762/bjoc.15.218

• . Keywords: catalysis; C-RF bond; fluorination; fluoroalkylation; transition metals; Introduction Compared with other halogens (Cl, Br, I), fluorine (F) has completely different physical and chemical properties, such as a unique electronic structure, strongest electronegativity, and small atomic radius

1,2,3-Triazolium macrocycles in supramolecular chemistry

• Mastaneh Safarnejad Shad,
• Pulikkal Veettil Santhini and
• Wim Dehaen

Beilstein J. Org. Chem. 2019, 15, 2142–2155, doi:10.3762/bjoc.15.211

• -triazole units to more electrophilic 1,2,3-triazolium units by influencing both hydrogen bonding-like and anion–π interactions. Moreover, halogen bond (XB) and chalcogen bond (ChB) interactions (see Figure 1) also been applied for the selective detection of anions by exchanging C5–H protons with halogens

An overview of the cycloaddition chemistry of fulvenes and emerging applications

• Ellen Swan,
• Kirsten Platts and
• Anton Blencowe

Beilstein J. Org. Chem. 2019, 15, 2113–2132, doi:10.3762/bjoc.15.209

• reaction. This was demonstrated in a study by Gugelchuck et al. [71], where the reaction rate of various p-substituted 6-phenylpentafulvenes with maleimides was investigated. Substituents of an electron-donating nature (e.g., H, halogens) generally increased the reaction rate through stabilisation of the

Friedel–Crafts approach to the one-pot synthesis of methoxy-substituted thioxanthylium salts

• Kenta Tanaka,
• Yuta Tanaka,
• Mami Kishimoto,
• Yujiro Hoshino and
• Kiyoshi Honda

Beilstein J. Org. Chem. 2019, 15, 2105–2112, doi:10.3762/bjoc.15.208

• excellent yields (3f–h). The benzoyl chlorides bearing a variety of halogens were suitable for this reaction (3i–n). Although naphthalene is a sterically large group, the reaction proceeded smoothly (3o). The diaryl sulfide with ethoxy substituents furnished the corresponding product in moderate yield (3p

Vicinal difunctionalization of alkenes by four-component radical cascade reaction of xanthogenates, alkenes, CO, and sulfonyl oxime ethers

• Shuhei Sumino,
• Takahide Fukuyama,
• Mika Sasano,
• Ilhyong Ryu,
• Antoine Jacquet,
• Frédéric Robert and
• Yannick Landais

Beilstein J. Org. Chem. 2019, 15, 1822–1828, doi:10.3762/bjoc.15.176

• % yield, respectively. The conditions were shown to be compatible with the presence of nitriles, ethers and halogens. Alkenes having a tert-butyldimethylsilyl ether such as 6-siloxy-1-hexene 2c thus participated to the reaction to give 5e in 57% yield. Alkenes having a chlorine atom, as in 2d, were also

A golden opportunity: benzofuranone modifications of aurones and their influence on optical properties, toxicity, and potential as dyes

• Joza Schmitt and
• Scott T. Handy

Beilstein J. Org. Chem. 2019, 15, 1781–1785, doi:10.3762/bjoc.15.171

• the halogens, however, location is fairly important, with the 6 or 7 position being much less toxic (similar to tartrazine) and dramatically better than the unsubstituted base compound 1, with the unexpected exception of 7-bromo compound 10. Whether this trend is general or not for aurone compounds is

• displays a significant blue shift by roughly 40 nm. With respect to toxicity, halogens were the least toxic substituents, displaying the lowest cytotoxicity when at the 6- or 7-positions. Hydroxylation or substitution at the 4-position invariably lead to higher cytotoxicity, though often times no worse

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

Insertion of [1.1.1]propellane into aromatic disulfides

• Robin M. Bär,
• Gregor Heinrich,
• Martin Nieger,
• Olaf Fuhr and
• Stefan Bräse

Beilstein J. Org. Chem. 2019, 15, 1172–1180, doi:10.3762/bjoc.15.114

• product (with up to 98% yield) or a mixture of BCP and [2]staffane can be obtained. The reaction tolerates functional groups such as halogens, alkyl and methoxy groups. The separation of the corresponding BCP and [2]staffane products is challenging but possible by column chromatography and preparative TLC

Strong hyperconjugative interactions limit solvent and substituent influence on conformational equilibrium: the case of cis-2-halocyclohexylamines

• Camila B. Francisco,
• Cleverton S. Fernandes,
• Ulisses Z. de Melo,
• Roberto Rittner,
• Gisele F. Gauze and
• Ernani A. Basso

Beilstein J. Org. Chem. 2019, 15, 818–829, doi:10.3762/bjoc.15.79

• cause some effect on the conformational equilibrium. Freitas and co-workers have demonstred this effect on trans-1,2-dihalocyclohexanes [12], where the diequatorial repulsion between the bulky halogens make the diaxial conformer more stable. Similarly, in trans-2-halocyclohexanols the OH–X interaction

• halogens, as mentioned before, the pronounced ea preference observed in our case led us to investigate the specific effects that may be responsible for this behavior. Delocalization, electrostatic and steric interactions In order to determine which effects are responsible for the stabilization of each

• most stable rotamer in each conformation (see Supporting Information File 2 for full numerical data). In the PCA (Figure 6), two principal components described 94% of the results. The PC1 is able to differentiate the variables according to the halogens, while the PC2 distinguish the two conformations

Metal-free C–H mercaptalization of benzothiazoles and benzoxazoles using 1,3-propanedithiol as thiol source

• Yan Xiao,
• Bing Jing,
• Xiaoxia Liu,
• Hongyu Xue and
• Yajun Liu

Beilstein J. Org. Chem. 2019, 15, 279–284, doi:10.3762/bjoc.15.24

• groups as well as halogens are well tolerated under the developed reaction conditions. Benzoxazoles were also successfully converted to the corresponding thiols. The relatively lower yields can be attributed to the partial decomposition of benzoxazoles caused by KOH at high temperature. In order to get

Oxidative radical ring-opening/cyclization of cyclopropane derivatives

• Yu Liu,
• Qiao-Lin Wang,
• Zan Chen,
• Cong-Shan Zhou,
• Bi-Quan Xiong,
• Pan-Liang Zhang,
• Chang-An Yang and
• Quan Zhou

Beilstein J. Org. Chem. 2019, 15, 256–278, doi:10.3762/bjoc.15.23

• , Scheme 9) [62]. In this transformation, many substituted MCPs 1 with alkyl groups, Ts-protected amino groups, or halogens were tolerated well and gave the desired products 31 in good yields. Moreover, the product 31a could go through a further oxidation to afford two different products in the presence of

Organometallic vs organic photoredox catalysts for photocuring reactions in the visible region

• Aude-Héloise Bonardi,
• Frédéric Dumur,
• Guillaume Noirbent,
• Jacques Lalevée and
• Didier Gigmes

Beilstein J. Org. Chem. 2018, 14, 3025–3046, doi:10.3762/bjoc.14.282

• ]. Its absorption extends from UV until 450 nm and can thus be activated at 405 nm with a blue light. Eventually, the peripheral carbazoles can be substituted with halogens. This increases the rate of RISC, and red-shifts the absorption spectrum [81]. For example, with a bromo atom on the peripheral

Pd-Catalyzed microwave-assisted synthesis of phosphonated 13α-estrones as potential OATP2B1, 17β-HSD1 and/or STS inhibitors

• Rebeka Jójárt,
• Szabolcs Pécsy,
• György Keglevich,
• Mihály Szécsi,
• Réka Rigó,
• Csilla Özvegy-Laczka,
• Gábor Kecskeméti and
• Erzsébet Mernyák

Beilstein J. Org. Chem. 2018, 14, 2838–2845, doi:10.3762/bjoc.14.262

• inhibitory activity of natural estrone derivatives was the introduction of large halogens and phenethynyl or phenethyl functions onto C-2 of estrone. Their most potent compounds displayed nanomolar inhibitory activities. Our related previous work included the synthesis and in vitro 17β-HSD1 determination of

• similar derivatives of the hormonally inactive 13α-estrane core [21][22][23]. We found that 2- and/or 4-substitution with large halogens (Br or I) lead to submicromolar inhibitors irrespective of the position and number of the introduced halogens. In the case of phenethynyl- or phenethyl-13α-estrones

An overview on recent advances in the synthesis of sulfonated organic materials, sulfonated silica materials, and sulfonated carbon materials and their catalytic applications in chemical processes

• Hashem Sharghi,
• Pezhman Shiri and
• Mahdi Aberi

Beilstein J. Org. Chem. 2018, 14, 2745–2770, doi:10.3762/bjoc.14.253

• -withdrawing substitutions 7 with 4-hydroxycoumarin (34b) at 70 °C within short reaction times. All aromatic aldehydes 7 reacted with 4-hydroxycoumarin (34b) to form bis-coumarins bearing electron-donating groups, electron-withdrawing groups, and halogens 72 in very short reaction times and in high yields. In

Microwave-assisted synthesis of biologically relevant steroidal 17-exo-pyrazol-5'-ones from a norpregnene precursor by a side-chain elongation/heterocyclization sequence

• Gergő Mótyán,
• László Mérai,
• Márton Attila Kiss,
• Zsuzsanna Schelz,
• Izabella Sinka,
• István Zupkó and
• Éva Frank

Beilstein J. Org. Chem. 2018, 14, 2589–2596, doi:10.3762/bjoc.14.236

• on the reaction rates. The ring-closure of 4 with 5d–g containing electron-donating groups (Table 1, entries 1–4) took place within shorter reaction times (5–10 min) compared to phenylhydrazine (5b). On the other hand the presence of electron-withdrawing halogens on the aromatic ring of 5 (Table 1