Synthesis of organic liquid crystals containing selectively fluorinated cyclopropanes

• Zeguo Fang,
• Nawaf Al-Maharik,
• Peer Kirsch,
• Matthias Bremer,
• Alexandra M. Z. Slawin and
• David O’Hagan

Beilstein J. Org. Chem. 2020, 16, 674–680, doi:10.3762/bjoc.16.65

• . Notably for both the axial and equatorial conformers, the orientation of the CF2 group, and therefore its dipole, remains perpendicular to the long molecular axis (requirement for +ve dielectric). A similar result was obtained for stereoisomer 11b (see Supporting Information File 1) again with the first

• axial conformer at ΔG = +1.14 kcal/mol−1 above the ground state equatorial conformer. In this case the orientation of the CF2 group, and therefore the dipole, remains perpendicular to the long molecular axis (requirement for −ve dielectric) for both the axial and equatorial conformers. This analysis

Design and synthesis of diazine-based panobinostat analogues for HDAC8 inhibition

• Sivaraman Balasubramaniam,
• Sajith Vijayan,
• Liam V. Goldman,
• Xavier A. May,
• Kyra Dodson,
• Sweta Adhikari,
• Fatima Rivas,
• Davita L. Watkins and
• Shana V. Stoddard

Beilstein J. Org. Chem. 2020, 16, 628–637, doi:10.3762/bjoc.16.59

• computationally was revealed via experiment to be a better inhibitor than TOI2 and TOI3-rev. The result was observed presumably due to a variation in the binding mode for TOI4 that differs from that of TOI1, TOI2, and TOI3-rev. TOI4 was shown to observe a slightly different orientation of the core heterocyclic

• ring as well as a change in the orientation of the terminal indole ring. It is not clear if this difference in binding mode affected the ability of TOI4 to maintain a higher potency at lower concentrations. However, this observation does raise an interesting question: “Are certain modes of binding more

Synthesis and circularly polarized luminescence properties of BINOL-derived bisbenzofuro[2,3-b:3’,2’-e]pyridines (BBZFPys)

• Ryo Takishima,
• Yuji Nishii,
• Tomoaki Hinoue,
• Yoshitane Imai and
• Masahiro Miura

Beilstein J. Org. Chem. 2020, 16, 325–336, doi:10.3762/bjoc.16.32

• × 10−5 M) and in solid states (dispersed in Fomblin®). ORTEP drawings of 4b and 4c with 50% thermal probability. Hydrogen atoms and solvent molecules are omitted for clarity. Only major orientation of the disordered structure is displayed. The CCDC numbers are 1971471 for (R)-4b and 1971470 for (R)-4c

Formal preparation of regioregular and alternating thiophene–thiophene copolymers bearing different substituents

• Atsunori Mori,
• Keisuke Fujita,
• Chihiro Kubota,
• Toyoko Suzuki,
• Kentaro Okano,
• Takuya Matsumoto,
• Takashi Nishino and
• Masaki Horie

Beilstein J. Org. Chem. 2020, 16, 317–324, doi:10.3762/bjoc.16.31

• head-to-tail (HT) orientation with respect to the substituent at the 3-position are extensively studied to date since they generally show superior performances as materials [1][2][3][4][5][6]. Cross-coupling polymerization catalyzed by a transition metal complex has been recognized as an effective tool

Synthesis of 4-(2-fluorophenyl)-7-methoxycoumarin: experimental and computational evidence for intramolecular and intermolecular C–F···H–C bonds

• Vuyisa Mzozoyana,
• Fanie R. van Heerden and
• Craig Grimmer

Beilstein J. Org. Chem. 2020, 16, 190–199, doi:10.3762/bjoc.16.22

• this F···H interaction. The single crystal X-ray structure and the DFT-optimized structure showed that the fluorinated phenyl ring favors the orientation with the fluorine atom closer to H5 than H3. The X-ray structure also showed the existence of the intermolecular C–F···H–C interaction. Keywords

• a manner that brings the fluorine atom closer to H5 than H3. The same orientation was observed in the DFT-optimized (B3LYP/6-311G) structure. The X-ray data also showed the intermolecular C–F···H–C interactions which, together with other interactions, are resposible for the crystal packing

The use of isoxazoline and isoxazole scaffolding in the design of novel thiourea and amide liquid-crystalline compounds

• Itamar L. Gonçalves,
• Rafaela R. da Rosa,
• Vera L. Eifler-Lima and
• Aloir A. Merlo

Beilstein J. Org. Chem. 2020, 16, 175–184, doi:10.3762/bjoc.16.20

• behavior displayed SmA mesophase. A similar liquid crystal behavior can be seen in amides 19 and 21 where the isomers differ only in the relative orientation of the isoxazoline ring to the amide group, while the amide group in 19 can resonate to the nitrogen atom in the isoxazoline ring, 21 does not. All

Potent hemithioindigo-based antimitotics photocontrol the microtubule cytoskeleton in cellulo

• Alexander Sailer,
• Franziska Ermer,
• Yvonne Kraus,
• Rebekkah Bingham,
• Ferdinand H. Lutter,
• Julia Ahlfeld and
• Oliver Thorn-Seshold

Beilstein J. Org. Chem. 2020, 16, 125–134, doi:10.3762/bjoc.16.14

• match. Mainly, we assumed that re-orientation of the substituent pattern on one or both rings (e.g., re-orientation of the archetypal 3,4,5-trimethoxyphenyl south ring pattern to a 4,5,6-trimethoxyaryl pattern) might be needed to occupy a similar space. A wealth of CDIs have been reported, including

Reversible photoswitching of the DNA-binding properties of styrylquinolizinium derivatives through photochromic [2 + 2] cycloaddition and cycloreversion

• Sarah Kölsch,
• Heiko Ihmels,
• Jochen Mattay,
• Norbert Sewald and
• Brian O. Patrick

Beilstein J. Org. Chem. 2020, 16, 111–124, doi:10.3762/bjoc.16.13

• the differential absorption of linearly polarized light, which was polarized parallel and perpendicular to a reference axis, respectively, thus indicating the orientation of the transition moment of the chromophores relative to the electric field vector of the light [75]. The LD spectrum of DNA-bound

• an aggregation of the molecules along the DNA backbone at very high ligand concentrations. Nevertheless, the CD and LD spectroscopic data revealed at least some specific binding interactions of 4b with DNA that caused a distinct orientation of the aromatic units relative to the host DNA. In

Halogen-bonding-induced diverse aggregation of 4,5-diiodo-1,2,3-triazolium salts with different anions

• Xingyu Xu,
• Shiqing Huang,
• Zengyu Zhang,
• Lei Cao and
• Xiaoyu Yan

Beilstein J. Org. Chem. 2020, 16, 78–87, doi:10.3762/bjoc.16.10

• ], diiodoacetylene [15] and iodo/bromoethynyl moieties [16] have revealed that the XB-donors interacting with XB-acceptors (a nucleophilic region) are in approximately linear orientation. Besides, linearity, tunability and hydrophobicity (features of the XB ) are widely applied in crystal engineering, supramolecular

Synthesis of C-glycosyl phosphonate derivatives of 4-amino-4-deoxy-α-ʟ-arabinose

• Lukáš Kerner and
• Paul Kosma

Beilstein J. Org. Chem. 2020, 16, 9–14, doi:10.3762/bjoc.16.2

• orientation of the anomeric hydroxy group was proven by NOESY correlations between the H-2 proton and both geminal protons of the CH2P unit. A strong NOE was also observed for the upfield-shifted doublet of doublets at 1.71 ppm of the methylene group, which had an additional NOE correlation with the broad

• purification (Scheme 2). The equatorial arrangement of the C-glycosyl linkage was supported from the large value of the coupling constant J1,2 (9.5 Hz), indicating a 1,2-trans orientation of the respective protons. The monomethyl phosphonate ester 9 was then subjected to alkylation reactions in order to allow

Regioselectivity of glycosylation reactions of galactose acceptors: an experimental and theoretical study

• Enrique A. Del Vigo,
• Carlos A. Stortz and
• Carla Marino

Beilstein J. Org. Chem. 2019, 15, 2982–2989, doi:10.3762/bjoc.15.294

• regioselectivities were achieved in favor of the 1→3 products due to the equatorial orientation of the OH-3 group. A molecular modeling approach endorsed this general trend of favoring O-3 substitution, although it showed some failures to explain subtler factors governing the difference in regioselectivity between

Chemical tuning of photoswitchable azobenzenes: a photopharmacological case study using nicotinic transmission

• Lorenzo Sansalone,
• Jun Zhao,
• Matthew T. Richers and
• Graham C. R. Ellis-Davies

Beilstein J. Org. Chem. 2019, 15, 2812–2821, doi:10.3762/bjoc.15.274

• maintains the near-ideal chemical properties of Hecht’s 4FAB chromophores [12][13] (see below). The final synthetic challenge was the installation of a maleimide onto chromophore 2. The original AB photoswitchable probes which were cross-linked to cysteine mutants had amides with a reverse orientation [19

Emission solvatochromic, solid-state and aggregation-induced emissive α-pyrones and emission-tuneable 1H-pyridines by Michael addition–cyclocondensation sequences

• Natascha Breuer,
• Irina Gruber,
• Christoph Janiak and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2019, 15, 2684–2703, doi:10.3762/bjoc.15.262

• excited state [59]. Plotting Stokes shifts Δν̃ against the orientation polarizabilities Δƒ of the respective solvents (Lippert plot) [60] gives a reasonable linear correlation with a moderate fit of r2 = 0.970 (Figure 13). The orientation polarizabilities Δƒ were calculated according to Equation 1 where

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

• polarization (rearrangement of atomic bonds and valence angles) a certain dipolar orientation degree of freedom take place in PMMA within the lifetime of excited state of NR. The restriction of the orientational relaxation causes an inhomogeneous broadening of the fluorescence spectrum of NR and its excitation

Self-assembled coordination thioether silver(I) macrocyclic complexes for homogeneous catalysis

• Zhen Cao,
• Aline Lacoudre,
• Cybille Rossy and
• Brigitte Bibal

Beilstein J. Org. Chem. 2019, 15, 2465–2472, doi:10.3762/bjoc.15.239

• bis-alkylaryl thioether ligand to control the directionality and spatial orientation of its coordination to silver(I). Besides, 9,10-diphenylanthracenes (DPA) with ortho-substituted 9- and 10-aryl groups can exist as syn- or anti-atropisomers whose rotational barrier [46][47] ranges from 21 (ortho-H

Sugar-derived oxazolone pseudotetrapeptide as γ-turn inducer and anion-selective transporter

• Sachin S. Burade,
• Sushil V. Pawar,
• Tanmoy Saha,
• Navanath Kumbhar,
• Amol S. Kotmale,
• Manzoor Ahmad,
• Pinaki Talukdar and
• Dilip D. Dhavale

Beilstein J. Org. Chem. 2019, 15, 2419–2427, doi:10.3762/bjoc.15.234

• presence of oxazolone ring in 2b. Conformational study of 2a The downfield shift of amide NH protons δ > 7.5 ppm in 2a suggested the possible involvement of intramolecular hydrogen bonding [25]. The observed NOESY cross peaks of NH(I)↔NH2 indicated closer proximity and orientation on the same side (Figure

•  2). This is likely to involve (I)NH···NH2 weak intramolecular hydrogen bonding. The amide NH(II) showed strong cross peaks with H-2, H-5 of ring C, H-4 of ring B and weak cross peaks with H-1, H-6 of ring C indicating closer proximity and orientation of these protons on the same side. Appearance of

• strong NOE between NH(II)↔H-4 and weak NOE between NH(II)↔H-2 of ring B indicated the orientation of NH(II) towards the carbonyl group of ring A with the formation of intramolecular hydrogen bonding in a seven-membered ring leading to the γ-turn conformation (Figure 2). The involvement of amide NHs in

In water multicomponent synthesis of low-molecular-mass 4,7-dihydrotetrazolo[1,5-a]pyrimidines

• Irina G. Tkachenko,
• Sergey A. Komykhov,
• Vladimir I. Musatov,
• Svitlana V. Shishkina,
• Viktoriya V. Dyakonenko,
• Vladimir N. Shvets,
• Mikhail V. Diachkov,
• Valentyn A. Chebanov and
• Sergey M. Desenko

Beilstein J. Org. Chem. 2019, 15, 2390–2397, doi:10.3762/bjoc.15.231

• for both isomers (4.4 Hz for A and 11.2 Hz for B) are indicative of different relative orientations of these protons and suggested that these protons in isomer B have trans-orientation, whereas those in isomer A have cis-orientation. Further, NOE between methyl and hydroxy groups for B isomer and a

• merely weak NOE for those groups in isomer A further allowed to propose a cis-orientation of these substituents for isomer B and the opposite one for A (Scheme 4). Antioxidant properties of 9, 11, 14 Among the methods for the antioxidant activity (AOA) estimation, using 1,1-diphenyl-2-picrylhydrazyl

Excited state dynamics for visible-light sensitization of a photochromic benzil-subsituted phenoxyl-imidazolyl radical complex

• Yoichi Kobayashi,
• Yukie Mamiya,
• Katsuya Mutoh,
• Hikaru Sotome,
• Masafumi Koga,
• Hiroshi Miyasaka and
• Jiro Abe

Beilstein J. Org. Chem. 2019, 15, 2369–2379, doi:10.3762/bjoc.15.229

• constant of 38 ps. Although the clear mechanism is not yet elucidated at the present stage of the investigation, the reason for the two relaxation pathways (energy transfer and ISC) from the S1 state of the benzil unit of Benzil-PIC might be due to the difference in the mutual orientation of benzil and PIC

• units including the structural isomers (isomer A and isomer B). As was discussed above, the energy transfer is due to the overlap of the wave function of the both units, of which mechanism might be sensitive to the difference in the mutual orientation. Effect of triplet–triplet energy transfer Ultrafast

Perspective isomorphs – a new classification of molecular structures based on artistic and chemical concepts

• Jannis Neumann,
• Ansgar Schnurr and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2019, 15, 2319–2326, doi:10.3762/bjoc.15.224

• equivalent from one standpoint in a specific orientation. We termed such a group of such molecules perspective isomorphs. The general concept is outlined together with a nomenclature system. Furthermore, this concept has been visualized by artistic representations of molecules. The concept of perspective

• molecules (sub-nm) such direct observations of chemical compounds by the human eye are not possible. This results in a different understanding of the spatial relations of these objects and the observer. Because a molecule’s interaction with its environment differs depending on its position and orientation

• ] between molecules or specific parts within molecules, are highly dependent on the orientation of the interacting entities. In contrast, considerations of space on a supramolecular scale [7][8] or even the integration of an actual human viewer are mostly excluded in models of chemical concepts. The

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

• , thanks to through-space interactions. Modelling suggested that changing the relative orientation/distance of the chromophores would allow cooperative TPA enhancement to be achieved [51]. Thus, multistilbazole molecular structures of different topologies and number of dipolar chromophores, including small

• changes in the topology, relative orientation, and packing of the fluorophores [62]. Another example of fluorophores at two levels concerned the branches and the surface, as depicted in Figure 8. The fluorophore of the branches is the one shown in Figure 6, and the fluorophore of the surface is the one

Harnessing enzyme plasticity for the synthesis of oxygenated sesquiterpenoids

• Melodi Demiray,
• David J. Miller and
• Rudolf K. Allemann

Beilstein J. Org. Chem. 2019, 15, 2184–2190, doi:10.3762/bjoc.15.215

• previously [29]. However, the presence of monocyclic products indicates that this second ring closure does not occur with 12-methoxy-FDP (12). It is suggested that the 12-methoxy group enforces an orientation of the distal 10,11-double bond that is not conducive to the second ring closure. Subsequent

Azologization and repurposing of a hetero-stilbene-based kinase inhibitor: towards the design of photoswitchable sirtuin inhibitors

• Christoph W. Grathwol,
• Nathalie Wössner,
• Sören Swyter,
• Adam C. Smith,
• Enrico Tapavicza,
• Robert K. Hofstetter,
• Anja Bodtke,
• Manfred Jung and
• Andreas Link

Beilstein J. Org. Chem. 2019, 15, 2170–2183, doi:10.3762/bjoc.15.214

• derivatives very fast and thus disable photoisomerization [63]. However, in our enzyme assay no such reducing agents were present, which is why we assume that the photoswitchable diazeno group should still be intact in the enzyme assay mixture. Even if the change in space orientation does not alter binding

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

• effective molarity and the favorable orientation of the substrates inside the cavity [61]. Thus, a nanometer-sized macrocyclic receptor based on a photoactive porphyrin unit and anion-binding pyridinium and 1,2,3-triazolium units 15 was reported by Li and co-workers This receptor was synthesized via well

Multiple threading of a triple-calix[6]arene host

• Veronica Iuliano,
• Roberta Ciao,
• Emanuele Vignola,
• Carmen Talotta,
• Patrizia Iannece,
• Margherita De Rosa,
• Annunziata Soriente,
• Carmine Gaeta and
• Placido Neri

Beilstein J. Org. Chem. 2019, 15, 2092–2104, doi:10.3762/bjoc.15.207

• evidences for the formation of the (4+)36 pseudo[4]rotaxanes was obtained by a 1H NMR study (Figure 8d). A careful analysis of the ArCH2Ar region of these spectra evidenced again a syn orientation of the aromatic rings of calix[6]-wheels corresponding to a cone conformation, which was also confirmed by the

α-Photooxygenation of chiral aldehydes with singlet oxygen

• Dominika J. Walaszek,
• Magdalena Jawiczuk,
• Jakub Durka,
• Olga Drapała and
• Dorota Gryko

Beilstein J. Org. Chem. 2019, 15, 2076–2084, doi:10.3762/bjoc.15.205

• fragments of molecule) in the antiperiplanar orientation as a result of steric repulsion, the absolute configuration at position 2 was assigned as (2R) in both compounds syn-6 and anti’-6 (Figure 1a). The absolute configuration of the second stereocenter at C3 with the phenyl substituent was determined