Fluorinated phenylalanines: synthesis and pharmaceutical applications

• Laila F. Awad and
• Mohammed Salah Ayoup

Beilstein J. Org. Chem. 2020, 16, 1022–1050, doi:10.3762/bjoc.16.91

• over the last few decades. ᴅ- or ʟ-fluorinated phenylalanines have had considerable industrial and pharmaceutical applications and they have been expanded also to play an important role as potential enzyme inhibitors as well as therapeutic agents and topography imaging of tumor ecosystems using PET

• -difluorophenylalanine derivatives 42a,b in quantitative yields [45] (Scheme 9). The radiolabeled 2-[18F]-fluoro-ʟ-phenylalanine 46 was synthesized as a promising radiopharmaceutical agent for molecular imaging by positron emission tomography (PET). The three-step synthesis of 46 started from [18F]-fluoride exchange in

• imaging [58] (Scheme 21). 1.9. Alkylation and hydrolysis of Ni(II) or Zn(II) complexes The synthesis of a series of fluorinated phenylalanines was achieved by transamination reactions between (R) or (S)-(15-aminomethyl-14-hydroxy-5,5-dimethyl-2,8-dithia[9](2,5)pyridinophanes) 96 and the sodium salt of o

Cation-induced ring-opening and oxidation reaction of photoreluctant spirooxazine–quinolizinium conjugates

• Phil M. Pithan,
• Sören Steup and
• Heiko Ihmels

Beilstein J. Org. Chem. 2020, 16, 904–916, doi:10.3762/bjoc.16.82

• -binding properties to be used as DNA-sensitive fluorescent probes in cell imaging [60][61][62] or as photoswitchable DNA ligands [63]. Therefore, we were interested in a combination of the photochromic properties of the spirooxazine moiety with the advantageous photophysical and biological properties of

Towards triptycene functionalization and triptycene-linked porphyrin arrays

• Gemma M. Locke,
• Keith J. Flanagan and
• Mathias O. Senge

Beilstein J. Org. Chem. 2020, 16, 763–777, doi:10.3762/bjoc.16.70

• biological labelling and are known photostable substitutes for fluorescein, giving them applications in cell imaging [20]. Due to the conjugated π-electron system present in BODIPYs they are more electron rich than porphyrins and possess an intense UV–vis absorption at approximately 400 nm, making them ideal

Synthesis of C₇₀-fragment buckybowls bearing alkoxy substituents

• Yumi Yakiyama,
• Shota Hishikawa and
• Hidehiro Sakurai

Beilstein J. Org. Chem. 2020, 16, 681–690, doi:10.3762/bjoc.16.66

• ; anal. calcd for C29H14O2(H2O)0.4: C, 86.73%; H, 3.71%; found: C, 86.58%; H, 3.50%. Single crystal X-ray analysis The diffraction data for 5a and 5c were collected on a Rigaku FR-E Superbright rotating-anode X-ray source with a Mo-target (λ = 0.71073 Å) equipped with a Rigaku RAXIS VII imaging plate as

Synthesis of triphenylene-fused phosphole oxides via C–H functionalizations

• Md. Shafiqur Rahman and
• Naohiko Yoshikai

Beilstein J. Org. Chem. 2020, 16, 524–529, doi:10.3762/bjoc.16.48

• -containing ladder molecules and their application as fluorescence probes for biological imaging [10][11]. Marinetti extensively studied the synthesis of phosphahelicenes with linear fusion of the phosphole and the carbohelicene units [12], and their applications in asymmetric catalysis [13] and organic light

Photophysics and photochemistry of NIR absorbers derived from cyanines: key to new technologies based on chemistry 4.0

• Bernd Strehmel,
• Christian Schmitz,
• Ceren Kütahya,
• Yulian Pang,
• Anke Drewitz and
• Heinz Mustroph

Beilstein J. Org. Chem. 2020, 16, 415–444, doi:10.3762/bjoc.16.40

• aprotic matrix takes the function of the matrix with absorber embedded. Typically, digital imaging in Computer to Plate technology (CtP) [10][11][12][13][14], curing of liquid coatings [5][15], powder coatings [16][17], laser drying [18][19][20], laser welding [21][22][23][24][25], or laser marking of

• plastics [26][27][28][29][30][31] represent some practical examples. Nevertheless, cyanines have held a long history regarding their practical use, which started to use such materials as sensitizers in silver halide photography [32][33][34] until the point when electronic media took their place in imaging

• also enabled the introduction of reactive groups such as -N=C=S facilitating them to function as marker in biological/imaging applications [9]. This reaction occurred with good yields and extended the use of such NIR absorbers in more fields [1][2][7][8][9]. In general, this functionalization resulted

Recent developments in photoredox-catalyzed remote ortho and para C–H bond functionalizations

• Rafia Siddiqui and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 248–280, doi:10.3762/bjoc.16.26

• delivery, medical imaging, etc.). Therefore, functionalization of arenes with this isotope is an important task. Although several reports are available in the literature for these transformations, they suffer from poor reactivity, unreactive starting material, and lower activities of the 18F-labeled

Combination of multicomponent KA² and Pauson–Khand reactions: short synthesis of spirocyclic pyrrolocyclopentenones

• Riccardo Innocenti,
• Elena Lenci,
• Gloria Menchi and
• Andrea Trabocchi

Beilstein J. Org. Chem. 2020, 16, 200–211, doi:10.3762/bjoc.16.23

• Riccardo Innocenti Elena Lenci Gloria Menchi Andrea Trabocchi Department of Chemistry “Ugo Schiff”, University of Florence, Via della Lastruccia 13, 50019 Sesto Fiorentino, Florence, Italy, Interdepartmental Center for Preclinical Development of Molecular Imaging (CISPIM), University of Florence

A combinatorial approach to improving the performance of azoarene photoswitches

• Joaquin Calbo,
• Aditya R. Thawani,
• Rosina S. L. Gibson,
• Andrew J. P. White and
• Matthew J. Fuchter

Beilstein J. Org. Chem. 2019, 15, 2753–2764, doi:10.3762/bjoc.15.266

• including imaging applications [20], photopharmacology [21], supramolecular chemistry [22][23], responsive foams [24], coordination chemistry [25] and DNA nanotechnology [26][27]. Whilst the azopyrazoles have excellent properties for use in a variety of photo-addressable applications, it remains frustrating

Plasma membrane imaging with a fluorescent benzothiadiazole derivative

• Pedro H. P. R. Carvalho,
• Jose R. Correa,
• Karen L. R. Paiva,
• Daniel F. S. Machado,
• Jackson D. Scholten and
• Brenno A. D. Neto

Beilstein J. Org. Chem. 2019, 15, 2644–2654, doi:10.3762/bjoc.15.257

• -soluble and selective bioprobe for plasma membrane imaging. The new compound was efficiently synthesized in a two-step procedure with good yields. The photophysical properties were evaluated and the dye proved to have an excellent photostability in several solvents. DFT calculations were found in

• agreement with the experimental data and helped to understand the stabilizing intramolecular charge-transfer process from the first excited state. The new fluorescent derivative could be applied as selective bioprobe in several cell lines and displayed plasma-membrane affinity during the imaging experiments

• for all tested models. Keywords: benzothiadiazole; bioprobe; cell imaging; fluorescence; mitochondria; molecular architecture; plasma membrane; Introduction The selective staining of plasma membranes is of paramount importance to study cellular processes and events associated with this dynamic

A new approach to silicon rhodamines by Suzuki–Miyaura coupling – scope and limitations

• Thines Kanagasundaram,
• Antje Timmermann,
• Carsten S. Kramer and
• Klaus Kopka

Beilstein J. Org. Chem. 2019, 15, 2569–2576, doi:10.3762/bjoc.15.250

• application in STED (stimulated emission depletion) microscopy, as sensor molecules for, e.g., ions and as fluorophores for the optical imaging of tumors. Different strategies were already employed for their synthesis. Because of just three known literature examples in which Suzuki–Miyaura cross couplings

• intraoperative imaging of cancerous lesions, we were interested in silicon rhodamines due to their fluorescence properties in the biological window (650 nm to 1350 nm). While clinically approved fluorescence dyes like ICG (indocyanine green, Mw = 775 g/mol) have a high molecular weight and could therefore alter

• pharmacokinetic or -dynamic properties of the tumor tracers, silicon rhodamines are relatively small and already examined as fluorophores for the optical imaging of tumors. Using silicon rhodamine SiR700 a more enhanced tumor-to-background ratio in optical imaging could be achieved compared to the cyanine based

Probing of local polarity in poly(methyl methacrylate) with the charge transfer transition in Nile red

• Aydan Yadigarli,
• Qimeng Song,
• Sergey I. Druzhinin and
• Holger Schönherr

Beilstein J. Org. Chem. 2019, 15, 2552–2562, doi:10.3762/bjoc.15.248

• fluorescence was used to detect a lipid droplet in monkey aortic smooth muscle cells [16], for visualizing different proteins, such as lactoglobulin, casein and albumin [17]. In fluorescence lifetime imaging microscopy τf as a viable contrast parameter was employed to image lipid droplets in living HeLa cells

Targeted photoswitchable imaging of intracellular glutathione by a photochromic glycosheet sensor

• Xianzhi Chai,
• Hai-Hao Han,
• Yi Zang,
• Jia Li,
• Xiao-Peng He,
• Junji Zhang and
• He Tian

Beilstein J. Org. Chem. 2019, 15, 2380–2389, doi:10.3762/bjoc.15.230

• , People’s Republic of China 10.3762/bjoc.15.230 Abstract The development of photochromic fluorescence sensors with dynamic and multiple-signaling is beneficial to the improvement of biosensing/imaging precision. However, elaborate designs with complicated molecular structures are always required to

• photoswitchable imaging of intracellular glutathione (GSH). The photochromic glycosheet manifests significantly turn-on fluorescence and dynamic ON/OFF fluorescence signals in response to GSH, which makes it favorable for intracellular GSH double-check in targeted human hepatoma cell line (HepG2) through the

• recognition between β-D-galactoside and asialoglycoprotein receptor (ASGPr) on cell membranes. The dynamic fluorescence signals and excellent selectivity for detection and imaging of GSH ensure the precise determination of cell states, promoting its potential applications in future disease diagnosis and

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

• the use in multimodal (PET/OI) medical imaging of mitochondria in cancerous cells. Results: A dihalogenated fluorinatable pyridinyl rhodamine could be successfully synthesized with the high yield of 85% by application of a halogen dance (HD) rearrangement. The near-infrared dye shows a quantum yield

• coefficient >0.8). The dye is suitable for live cell STED nanoscopy imaging and shows a nontoxic profile which makes it an appropriate candidate for medical imaging. Conclusions: We present a biocompatible, nontoxic, small molecule near-infrared dye with the option of subsequent radiolabelling and excellent

• optical properties for medical and bioimaging. As a compound with intrinsic mitochondria targeting ability, the radiolabelled analogue can be applied in multimodal (PET/OI) imaging of mitochondria for diagnostic and therapeutic use in, e.g., cancer patients. Keywords: halogen-dance reaction

Fluorescent phosphorus dendrimers excited by two photons: synthesis, two-photon absorption properties and biological uses

• Anne-Marie Caminade,
• Artem Zibarov,
• Eduardo Cueto Diaz,
• Aurélien Hameau,
• Maxime Klausen,
• Kathleen Moineau-Chane Ching,
• Jean-Pierre Majoral,
• Jean-Baptiste Verlhac,
• Olivier Mongin and
• Mireille Blanchard-Desce

Beilstein J. Org. Chem. 2019, 15, 2287–2303, doi:10.3762/bjoc.15.221

• dendrimers have water-solubilizing functions as terminal groups, and fluorophores at the core or in the branches. They have been used as fluorescent tools in biology for different purposes, such as tracers for imaging blood vessels of living animals, for determining the phenotype of cells, for deciphering

• nanocrystals [6]), widely used for imaging live cells, for in vivo imaging and diagnostics [7]. Even if the properties of quantum dots have been compared with those of classical organic fluorophores [8], organic fluorophores having giant TPA properties are far less common [9], although there are noticeable

• use concerned in vivo imaging with some of the dumbbell-like dendrimers. The second generation of the dendrimer shown in Figure 9 was injected to a rat and the two-photon imaging of the vessels of the living rat olfactory bulb could be obtained [56]. The other dumbbell-like dendrimer shown in Scheme 5

Aggregation-induced emission effect on turn-off fluorescent switching of a photochromic diarylethene

• Luna Kono,
• Yuma Nakagawa,
• Ayako Fujimoto,
• Ryo Nishimura,
• Yohei Hattori,
• Toshiki Mutai,
• Nobuhiro Yasuda,
• Kenichi Koizumi,
• Satoshi Yokojima,
• Shinichiro Nakamura and
• Kingo Uchida

Beilstein J. Org. Chem. 2019, 15, 2204–2212, doi:10.3762/bjoc.15.217

• , diarylethene derivatives with photoswitchable fluorescent properties were prepared. They are applicable for fluorescence imaging including bio-imaging. On the other hand, a new system called “excited state intramolecular proton transfer (ESIPT)” is reported. In the system, absorption and emission bands are

• , fluorescence switching for molecular level recording [4], multiple-fluorescence for logic circuits [5] as well as biological applications [6] and super-resolution microscopy for bio-imaging [7][8]. The fluorescence switching in solid state is attracting much attention from both scientific and technological

Synthesis and properties of sulfur-functionalized triarylmethylium, acridinium and triangulenium dyes

• Marco Santella,
• Eduardo Della Pia,
• Jakob Kryger Sørensen and
• Bo W. Laursen

Beilstein J. Org. Chem. 2019, 15, 2133–2141, doi:10.3762/bjoc.15.210

• , synthesis and studies of organic fluorescent dyes have witnessed a revival in recent years, in particular due to their applications in imaging and biomedical assays and analytical techniques [1][2][3][4][5]. The desire to detect minute amounts of dye, ideally single molecules [6][7], in complex biological

Archangelolide: A sesquiterpene lactone with immunobiological potential from Laserpitium archangelica

• Silvie Rimpelová,
• Michal Jurášek,
• Lucie Peterková,
• Jiří Bejček,
• Vojtěch Spiwok,
• Miloš Majdl,
• Michal Jirásko,
• Miloš Buděšínský,
• Juraj Harmatha,
• Eva Kmoníčková,
• Pavel Drašar and
• Tomáš Ruml

Beilstein J. Org. Chem. 2019, 15, 1933–1944, doi:10.3762/bjoc.15.189

• these compounds for further work including synthetic modifications using azide–alkyne Huisgen cycloaddition. We previously showed the preparation of fluorescent trilobolide conjugates [8] that retained the activity of the parental compounds and proved to be useful for live-cell imaging. In this article

• tested cancer cell lines nor in primary cells. To explain the reason for different cytotoxicity of compound 1 compared to compound 2 and thapsigargin, we prepared its fluorescent derivative for live-cell imaging studies, which determined its intracellular localization in endoplasmic reticulum and

• study U-2 OS and MRC-5 cells (1·105 cells per well) were seeded on 35 mm glass bottom dishes for live-cell imaging (MatTek Corporation, USA) and left to adhere for 24 h. Then, the cells were washed with phosphate-buffered saline (PBS) and incubated with compound 5 or dansyl amide fluorophore (0.1–2.0 µM

Identification of optimal fluorescent probes for G-quadruplex nucleic acids through systematic exploration of mono- and distyryl dye libraries

• Xiao Xie,
• Michela Zuffo,
• Marie-Paule Teulade-Fichou and
• Anton Granzhan

Beilstein J. Org. Chem. 2019, 15, 1872–1889, doi:10.3762/bjoc.15.183

• (up to 150 nm) and, in certain cases, structural selectivity with respect to one or another G4 folding topology. These dyes can be considered as promising G4-responsive sensors for in vitro or imaging applications. As a possible application, we implemented a simple two-dye fluorimetric assay allowing

• ][21][22][23]. Also, there have been promising reports on cellular imaging of G4-DNA [24][25][26][27][28][29] and G4-RNA [30][31][32][33] structures using small-molecule probes. A large number of fluorescent probes for G4-DNA and RNA have thus emerged in the last years, as summarized in several recent

• , 17a and 18a (Figure 9), were chosen for fluorescence quantum yield and brightness measurements, in order to assess their potential for imaging applications. The quantum yield of dyes was measured in the 1.2–3 µM concentration range, in the absence or in the presence of an excess of two G4-DNA analytes

Nanopatterns of arylene–alkynylene squares on graphite: self-sorting and intercalation

• Tristan J. Keller,
• Joshua Bahr,
• Kristin Gratzfeld,
• Nina Schönfelder,
• Marcin A. Majewski,
• Marcin Stępień,
• Sigurd Höger and
• Stefan-S. Jester

Beilstein J. Org. Chem. 2019, 15, 1848–1855, doi:10.3762/bjoc.15.180

• ), (f), (i), (l) 1b; c = 1 × 10−6 M, VS = −0.4 V, It = 26 pA; a = (5.6 ± 0.2) nm, b = (4.0 ± 0.2) nm, γ(a,b) = (74 ± 2)°; γ(a,d1) = (5 ± 1)°; γ(b,d2) = (9 ± 1)°; α◊ = (88 ± 4)°. All samples were thermally annealed for 20 s at 80 °C prior to imaging. All image sizes are 15.4 × 15.4 nm2. The red lines

Synthesis, photophysical and electrochemical properties of pyridine, pyrazine and triazine-based (D–π–)₂A fluorescent dyes

• Keiichi Imato,
• Toshiaki Enoki,
• Koji Uenaka and
• Yousuke Ooyama

Beilstein J. Org. Chem. 2019, 15, 1712–1721, doi:10.3762/bjoc.15.167

• solvents are fairly large (Table 1). Thus, the fact indicates that the (D–π–)2A fluorescent dyes have advantageous characteristics as emitters for OLEDs and fluorescence probes for biological imaging. It is well accepted that the dipole–dipole interactions between the fluorescent dye and the solvent

Complexation of a guanidinium-modified calixarene with diverse dyes and investigation of the corresponding photophysical response

• Yu-Ying Wang,
• Yong Kong,
• Zhe Zheng,
• Wen-Chao Geng,
• Zi-Yi Zhao,
• Hongwei Sun and
• Dong-Sheng Guo

Beilstein J. Org. Chem. 2019, 15, 1394–1406, doi:10.3762/bjoc.15.139

• photoactivity of photosensitizers (PSs) were annihilated by the complexation of guanidinium-modified calix[5]arene pentadodecyl ether while reactivated by adenosine triphosphate (a cancer biomarker) displacement. This novel supramolecular phototheranostics strategy realized both tumor-selective imaging and

• discussed. The established toolbox of reporter pairs is expected to shed light on applications in the areas of IDA and STA methodologies, and the obtained fundamental insights are prerequisite for future applications in imaging, lasing, activatable phototheranostics, manufacturing organic luminescent

• systemic delivery; “super”-quenching minimizes the imaging background and phototoxicity to normal tissues [27]. The complexation of GC5A with ICT dyes 1,8-ANS and 2,6-TNS are considered involving ICT processes in their photophysics [40][41] because of their intramolecular electron-donating and electron

Formation of an unexpected 3,3-diphenyl-3H-indazole through a facile intramolecular [2 + 3] cycloaddition of the diazo intermediate

• Andrew T. King,
• Hugh G. Hiscocks,
• Lidia Matesic,
• Mohan Bhadbhade,
• Roger Bishop and
• Alison T. Ung

Beilstein J. Org. Chem. 2019, 15, 1347–1354, doi:10.3762/bjoc.15.134

• body. Synthons are becoming more prevalent in imaging modalities like positron emission tomography (PET) as there is a greater need to further investigate lesions, and disease tissues on the molecular level. However, issues with the stability of sulfonyl fluorides have been reported in the literature

Efficient resolution of racemic crown-shaped cyclotriveratrylene derivatives and isolation and characterization of the intermediate saddle isomer

• Sven Götz,
• Andreas Schneider and
• Arne Lützen

Beilstein J. Org. Chem. 2019, 15, 1339–1346, doi:10.3762/bjoc.15.133

• are Xe inclusion complexes that are of special interest as they help to establish laser-polarized 129Xe NMR spectroscopy for the imaging in biological systems [22][23][24][25]. For the formation of Xe cryptophane complexes, cryptophane-1.1.1 has proven to be a very suitable host as it still shows the

Synthesis of dipolar molecular rotors as linkers for metal-organic frameworks

• Sebastian Hamer,
• Fynn Röhricht,
• Marius Jakoby,
• Ian A. Howard,
• Xianghui Zhang,
• Christian Näther and
• Rainer Herges

Beilstein J. Org. Chem. 2019, 15, 1331–1338, doi:10.3762/bjoc.15.132

• fabrication of an array of dipolar rotors with a ferroelectric ground state and a Curie temperature above room temperature [30]. Such materials would have a number of exciting optical and electronic properties and applications such as signal processing and imaging. Phase transition from a stochastic to an