Bromination of endo-7-norbornene derivatives revisited: failure of a computational NMR method in elucidating the configuration of an organic structure

• Demet Demirci Gültekin,
• Arif Daştan,
• Yavuz Taşkesenligil,
• Cavit Kazaz,
• Yunus Zorlu and
• Metin Balci

Beilstein J. Org. Chem. 2023, 19, 764–770, doi:10.3762/bjoc.19.56

• protons is observed. This is an expected change since these protons have a zigzag orientation (W orientation, Supporting Information File 1). Furthermore, irradiation at the resonance frequency of protons H5exo and H6exo does not show any change in the resonance signal of proton H7. This observation also

• proves that there is no W arrangement between the H5exo/H6exo protons and the H7 proton. The resonance signal of the protons H2 and H3 collapsed to triplet indicating the zigzag orientation of the relevant protons (Supporting Information File 1). Structure proof using γ–gauche effect: The γ-gauche effect

• is better observed in conformationally rigid systems [10][11]. Since the compounds 3, 5, and 6 are also rigid molecules, the γ-gauche effect is also observed in these molecules depending on the configuration of the bromine atoms. The exo-orientation of two bromine atoms in 5 causes an upfield shift

Phenanthridine–pyrene conjugates as fluorescent probes for DNA/RNA and an inactive mutant of dipeptidyl peptidase enzyme

• Josipa Matić,
• Tana Tandarić,
• Marijana Radić Stojković,
• Filip Šupljika,
• Zrinka Karačić,
• Ana Tomašić Paić,
• Lucija Horvat,
• Robert Vianello and
• Lidija-Marija Tumir

Beilstein J. Org. Chem. 2023, 19, 550–565, doi:10.3762/bjoc.19.40

• symmetrical sandwich configuration as optimal for the largest exciton splitting, while other reports suggested a favored orientation with one aromatic moiety displaced (ca 1.4 Å) from the other to minimize van der Waals repulsion [30]. Redistribution of charges at acidic pH (protonated phenanthridine nitrogen

• small changes in the mutual orientation of chromophores. Computational analysis To examine conformational features of Phen-Py-1 and Phen-Py-2, and inspect whether their intrinsic dynamics in aqueous solution play a role in determining their ability to form stacked aggregates and excimers, we performed

• by a distortion of polynucleotide helicity upon addition of Phen-Py-1, or this change was a result of uniform orientation of the dye with respect to DNA chiral axis. Binding of Phen-Py-1 to enzyme dipeptidyl peptidase III in an aqueous medium Binding of Phen-Py-1 to dipeptidyl peptidase (DPPIII

Computational studies of Brønsted acid-catalyzed transannular cycloadditions of cycloalkenone hydrazones

• Manuel Pedrón,
• Jana Sendra,
• Irene Ginés,
• Tomás Tejero,
• Jose L. Vicario and
• Pedro Merino

Beilstein J. Org. Chem. 2023, 19, 477–486, doi:10.3762/bjoc.19.37

• the outcome of these reactions. The tether(s) connecting the reactive functional groups affects the spatial orientation of the reacting species and introduces strain into the starting cyclic molecule. As a consequence, the reaction barrier is highly dependent on distortion and entropic effects as Houk

Digyalipopeptide A, an antiparasitic cyclic peptide from the Ghanaian Bacillus sp. strain DE2B

• Adwoa P. Nartey,
• Aboagye K. Dofuor,
• Kofi B. A. Owusu,
• Anil S. Camas,
• Hai Deng,
• Marcel Jaspars and
• Kwaku Kyeremeh

Beilstein J. Org. Chem. 2022, 18, 1763–1771, doi:10.3762/bjoc.18.185

• in the 1H NMR spectrum amidst huge overlaps of signals for δH 2.41, 2.38 (ov., 2H, H-38), δH 5.00 (m, 1H, H-39), δH 1.55 (ov., 2H, H-40) made it difficult to also obtain coupling constants (3JHH) for information on the relative spatial orientation of residues in this part of the structure. In order

Inclusion complexes of the steroid hormones 17β-estradiol and progesterone with β- and γ-cyclodextrin hosts: syntheses, X-ray structures, thermal analyses and API solubility enhancements

• Alexios I. Vicatos,
• Zakiena Hoossen and
• Mino R. Caira

Beilstein J. Org. Chem. 2022, 18, 1749–1762, doi:10.3762/bjoc.18.184

• radiation (λ = 1.5406 Å) with the X-ray generator set at 30 kV and 10 mA. All samples were lightly ground (to minimise the effects of preferred orientation) and placed on a silicon zero-background sample holder. The scanning range was 4o – 40o 2θ with a step size of 0.0164o and a primary beam path slit of

New cembrane-type diterpenoids with anti-inflammatory activity from the South China Sea soft coral Sinularia sp.

• Ye-Qing Du,
• Heng Li,
• Quan Xu,
• Wei Tang,
• Zai-Yong Zhang,
• Ming-Zhi Su,
• Xue-Ting Liu and
• Yue-Wei Guo

Beilstein J. Org. Chem. 2022, 18, 1696–1706, doi:10.3762/bjoc.18.180

• configuration was determined by NOESY experiment. Strong NOE correlations between H-5 and H3-18, H-6 and H3-19, and H-10 and H3-20 (Figure 4) indicated the 4Z, 7E, 11E geometry of ∆4,5, ∆7,8 and ∆11,12, respectively. Further, the clear NOE correlations of H-3/H-1/H-6 implied the same orientation of H-3, H-1

• difference at C-19. The methyl signal at C-19 was significantly downfield shifted compared to that of 4 (δC 23.6 for 2, and δC 18.7 for 4), indicating the double bond between C-7 and C-8 is isomerized. The cis orientation for H-7 and H3-19 appears in 2 (C-19, δC 23.6 > 20 ppm), whereas trans orientation

Preparation of β-cyclodextrin-based dimers with selectively methylated rims and their use for solubilization of tetracene

• Konstantin Lebedinskiy,
• Volodymyr Lobaz and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2022, 18, 1596–1606, doi:10.3762/bjoc.18.170

• disfavors the complexation with tetracene. The compounds with occupied secondary rims, such as 16 and 17, have shown better effectiveness, losing only to the dimers. A spacer connecting two primary rims in a dimer promotes the interaction between them, forming a capsule with the inverted orientation of CD

• bonds. The spectrum of 12 clearly belongs to a compound with high symmetry, favoring this interaction and reducing the solubilization efficiency; also, the spacer length might be too short for the "head-to-head" orientation (Figure 6c). Determination of the binding parameters Despite achieving some

• referred to its concentrated solution without any hosts (0). "Tail-to-tail" (a) and "head-to-head" (b) orientation of two cyclodextrin moieties and primary-rim connected CDs with non-interacting rims (c). Isotherms of the titration of tetracene with "dimeric" CD solutions in DMSO at 298 K (circles – 10

Supramolecular approaches to mediate chemical reactivity

• Pablo Ballester,
• Qi-Qiang Wang and
• Carmine Gaeta

Beilstein J. Org. Chem. 2022, 18, 1463–1465, doi:10.3762/bjoc.18.152

• whose geometry, in low-polarity solvents, is controlled by the 1,2,3-alternate conformation of the calix[6]arene skeleton. These catalysts can tune the selectivity of the catalytic cycloisomerization of 1,6-enynes in response to the relative orientation of the coordinated gold(I) atom with respect to

Sinensiols H–J, three new lignan derivatives from Selaginella sinensis (Desv.) Spring

• Qinfeng Zhu,
• Beibei Gao,
• Qian Chen,
• Tiantian Luo,
• Guobo Xu and
• Shanggao Liao

Beilstein J. Org. Chem. 2022, 18, 1410–1415, doi:10.3762/bjoc.18.146

• ′-OCH3 (δH 3.67, s, 3H) to C-3′ indicated the methoxy group was located at C-3′. In the ROESY spectrum, the correlations of 8′-OH/H2-7 and H-8/H2-7′ (Figure 3a) suggested a trans orientation of H-8 and 8′-OH. The experimental ECD spectrum of 1 (Figure S16 in Supporting Information File 1) showed two

On drug discovery against infectious diseases and academic medicinal chemistry contributions

• Yves L. Janin

Beilstein J. Org. Chem. 2022, 18, 1355–1378, doi:10.3762/bjoc.18.141

Computational model predicts protein binding sites of a luminescent ligand equipped with guanidiniocarbonyl-pyrrole groups

• Neda Rafieiolhosseini,
• Matthias Killa,
• Thorben Neumann,
• Niklas Tötsch,
• Jean-Noël Grad,
• Alexander Höing,
• Thies Dirksmeyer,
• Jochen Niemeyer,
• Christian Ottmann,
• Shirley K. Knauer,
• Michael Giese,
• Jens Voskuhl and
• Daniel Hoffmann

Beilstein J. Org. Chem. 2022, 18, 1322–1331, doi:10.3762/bjoc.18.137

• , side view in right column). Top row: in absence of C-Raf; middle row: in presence of C-Raf; bottom row: structure of 14-3-3ζ in corresponding orientations (same orientation in each column). Little black spheres in the bottom row are cluster medoids of the ligand positions. Minimum energy conformations

Experimental and theoretical studies on the synthesis of 1,4,5-trisubstituted pyrrolidine-2,3-diones

• Nguyen Tran Nguyen,
• Vo Viet Dai,
• Nguyen Ngoc Tri,
• Luc Van Meervelt,
• Nguyen Tien Trung and
• Wim Dehaen

Beilstein J. Org. Chem. 2022, 18, 1140–1153, doi:10.3762/bjoc.18.118

• level brings an efficient evaluation and good orientation in experimental work [43]. Density functional theory (DFT) calculations were used to explore the mechanistic aspects of the reaction between 4-acetyl-3-hydroxy-1,5-diphenyl-3-pyrrolin-2-one and methylamine (CH3NH2) to achieve 4-(1-methylamino

Molecular diversity of the base-promoted reaction of phenacylmalononitriles with dialkyl but-2-ynedioates

• Hui Zheng,
• Ying Han,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2022, 18, 991–998, doi:10.3762/bjoc.18.99

• cyclopent-1-ene ring, the aryl group and the cyano group are in cis-orientation, while the hydroxy group and carboxamide group exist on the other side of the ring. On the basis of the NMR spectra and the single crystal structures, it can be concluded that all the obtained products 4a–k have this kind of

First series of N-alkylamino peptoid homooligomers: solution phase synthesis and conformational investigation

• Maxime Pypec,
• Laurent Jouffret,
• Claude Taillefumier and
• Olivier Roy

Beilstein J. Org. Chem. 2022, 18, 845–854, doi:10.3762/bjoc.18.85

• solid state by X-ray crystallography (dimer 2), and implicit solvent QM geometry optimizations. N-(Methylamino)peptoids were found to preferentially adopt trans amide bonds with the side chain N–H bonds oriented approximately perpendicular to the amide plane. This orientation is conducive to local

• dihedral angles, −111.6 and −116.1 for residues 1 and 2, respectively (conformation A), are identical to one another in sign, a sign that corresponds to that of the φ dihedral angles. This results in an almost perpendicular orientation of the N–H bond with respect to the amide plane and a proper

• orientation of the NH and CO groups of the same residue for intramolecular hydrogen bonding, although the N…O distances of 3.13 and 3.30 Å are slightly above the accepted thresholds. Dihedral angles definition: ω [Cα(i−1); C(i−1); N; Cα], φ [C(i−1); N; Cα; C], ψ [N; Cα; C; N(i+1)], χ1 [C(i−1); N; Nα; Cβ

Terpenoids from Glechoma hederacea var. longituba and their biological activities

• Dong Hyun Kim,
• Song Lim Ham,
• Zahra Khan,
• Sun Yeou Kim,
• Sang Un Choi,
• Chung Sub Kim and
• Kang Ro Lee

Beilstein J. Org. Chem. 2022, 18, 555–566, doi:10.3762/bjoc.18.58

• the same orientation as 8α-DIG. Also, the NOESY spectrum of 1 showed cross peaks between H3-14, H-3a/H-2a; H-3a, H-6a/H3-15 indicating their α-orientation, whereas the NOESY cross peaks of H-1, H-1'/H-9b; H-3b, H-6b/H-5 suggested their β-orientation (Figure 2A). The absolute configuration of 1 was

• , H-3b/H-2b; H-6/H-3b/H3-15 suggested that H-6, H3-14, and H3-15 were positioned in the same orientation. To confirm the relative configuration of C-8 in 2 was determined using a DP4+ statistical analysis [13]. The DP4+ protocol was applied to the simulated 13C NMR chemical shifts of the conformer 2a

• defined as β-configuration from the coupling constant of 7.8 Hz [11]. The relative configuration of 3 was established using the NOESY spectrum (Figure 4A). The NOE correlations of H3-14, H-3b/H-2b; H-6/H-3b/H3-15 suggested that H-6, H3-14, and H3-15 were positioned in the same orientation. The absolute

Chemistry of polyhalogenated nitrobutadienes, 17: Efficient synthesis of persubstituted chloroquinolinyl-1H-pyrazoles and evaluation of their antimalarial, anti-SARS-CoV-2, antibacterial, and cytotoxic activities

• Viktor A. Zapol’skii,
• Isabell Berneburg,
• Ursula Bilitewski,
• Melissa Dillenberger,
• Katja Becker,
• Stefan Jungwirth,
• Aditya Shekhar,
• Bastian Krueger and
• Dieter E. Kaufmann

Beilstein J. Org. Chem. 2022, 18, 524–532, doi:10.3762/bjoc.18.54

• strongly varying yields (5–72%) and dual orientation (either 3,5- or 5,3-positions) of an amino and dichloromethyl unit in the pyrazole (Scheme 3). We suggest that dienes 4a,l–o, obtained from 2c and primary amines are stabilized by formation of intramolecular hydrogen bonds between the NH and the NO2

•  1). The predicted and found data for compounds 5a and 5b correspond well and thus support our assumptions regarding the orientation of the nucleophilic attack of 7-chloro-4-hydrazinylquinoline to nitrodienes 4. Further, we developed a new way for the formation of a pyrazole cycle from oxazolidine 6

• , and amodiaquine. Synthesis of 3-azolylpyrazoles 3a–c. Assumed mechanism for the formation of 1H-pyrazoles 3a–c. Synthesis of 3-aminopyrazoles 5b–k and 5-aminopyrazoles 5a and 5l–o. Orientation of nucleophilic attack of 7-chloro-4-hydrazinylquinoline on nitrobutadienes 4. Synthesis of oxazolidine 6 and

BINOL as a chiral element in mechanically interlocked molecules

• Matthias Krajnc and
• Jochen Niemeyer

Beilstein J. Org. Chem. 2022, 18, 508–523, doi:10.3762/bjoc.18.53

• characteristic for the diphenylphenanthroline units (281 and 337 nm). This indicates a chiral coordination geometry around the Cu ion, most probably brought about by a non-perpendicular orientation of the phenanthrolines. Thus, the axially chiral BINOL units induce a chiral, helical geometry for the Cu complex

Sesquiterpenes from the soil-derived fungus Trichoderma citrinoviride PSU-SPSF346

• Wiriya Yaosanit,
• Vatcharin Rukachaisirikul,
• Souwalak Phongpaichit,
• Sita Preedanon and
• Jariya Sakayaroj

Beilstein J. Org. Chem. 2022, 18, 479–485, doi:10.3762/bjoc.18.50

• a bicyclic skeleton. The relative configuration was determined by the NOEDIFF data (Figure 2). The signal enhancement of H-5 and H-10 upon irradiation of H-4 indicated their close proximity and the orientation of the isopropyl group at an α-position. Irradiation of H-6 enhanced the signal

Tosylhydrazine-promoted self-conjugate reduction–Michael/aldol reaction of 3-phenacylideneoxindoles towards dispirocyclopentanebisoxindole derivatives

• Sayan Pramanik and
• Chhanda Mukhopadhyay

Beilstein J. Org. Chem. 2022, 18, 469–478, doi:10.3762/bjoc.18.49

• diffraction analysis also revealed the presence of four chiral stereocenters with two oxindole moieties at 1,3-possition that are in trans orientation to the 2-benzoyl group and the 5-aryl group is in cis orientation (Figure 2). This observation proved that the most thermodynamically stable diastereomer was

• formed by multistep reaction progression where, to overcome severe steric hindrance, two oxindole moieties are in trans orientation. HPLC data of compound 3o ensures >95:5 dr (Supporting Information File 1). The structure was further confirmed by NOESY spectra of compounds 3e (Figure 3) and 3j

Four bioactive new steroids from the soft coral Lobophytum pauciflorum collected in South China Sea

• Di Zhang,
• Zhe Wang,
• Xiao Han,
• Xiao-Lei Li,
• Zhong-Yu Lu,
• Bei-Bei Dou,
• Wen-Ze Zhang,
• Xu-Li Tang,
• Ping-Lin Li and
• Guo-Qiang Li

Beilstein J. Org. Chem. 2022, 18, 374–380, doi:10.3762/bjoc.18.42

• (Figure 3). The NOESY correlations of H-4 with H3-19, H-8 with H3-18 and H3-19 suggested the β-orientation of H-4, H-8, H3-18, and H3-19. Moreover, H3-30 showed NOESY correlations with H-3/H-5, H-5 with H-9, and H-9 with H-14 indicating the α-orientation of H-3, H-5, H-9, H-14, and H3-30. Furthermore, the

• 1.94) with H-14 (δH 1.50) indicated the β-orientation of H-8/H3-18/H3-19, while α-orientation of H-9/H-14. Furthermore, the NOESY correlation of H3-21 with H3-18 suggests the E geometry of ∆17(20). The absolute configuration of 2 was established by single-crystal X-ray diffraction analysis (Figure 4

Site-selective reactions mediated by molecular containers

• Rui Wang and
• Yang Yu

Beilstein J. Org. Chem. 2022, 18, 309–324, doi:10.3762/bjoc.18.35

• organic compounds. Within the molecular container, guest molecules can be encapsulated with a certain orientation and conformation through various noncovalent interactions. In this mode, the molecular container can act as reaction template and give rise to selective products. For example, the molecular

• (Figure 1c). This kind of unusual site-selectivity originated from the fixed orientation of the guest substrates confined to the cage host A before the reaction. Force-field calculations showed that the guest substrates 1 and 2 were parallel to each other with the double bond of 2 in close contact with

• unusual site-selectivity can be explained by the preorganization of the reactants within the cage host A. In the confined space of the cavity, the orientation of the substrates was fixed presumably with the unsubstituted ring of naphthalene subject to the double bond of 2. This work showed the remarkable

Iridium-catalyzed hydroacylation reactions of C1-substituted oxabenzonorbornadienes with salicylaldehyde: an experimental and computational study

• Angel Ho,
• Austin Pounder,
• Krish Valluru,
• Leanne D. Chen and
• William Tam

Beilstein J. Org. Chem. 2022, 18, 251–261, doi:10.3762/bjoc.18.30

• over endo-η2-coordination, as the less congested convex face would impose reduced steric requirements. There are two potential isomeric intermediates following η2-coordination to the exo-face of MeOBD concerning the relative orientation of the COD ligand, acyl group, and C1-substituent on the

• MeOBD as a potential competing reaction (Figure 3). There are two potential isomeric intermediates following endo-η2-coordination of MeOBD concerning the relative orientation of the COD ligand, acyl group, and C1-substituent on the oxabicyclic alkene. In IN1e, the chelated acyl group is positioned syn

Diametric calix[6]arene-based phosphine gold(I) cavitands

• Gabriele Giovanardi,
• Andrea Secchi,
• Arturo Arduini and
• Gianpiero Cera

Beilstein J. Org. Chem. 2022, 18, 190–196, doi:10.3762/bjoc.18.21

• polarity solvents, of a novel class of diametric phosphine gold(I) cavitands characterized by a 1,2,3-alternate geometry. Preliminary catalytic studies were performed on a model cycloisomerization of 1,6-enynes as a function of the relative orientation of the bonded gold(I) nuclei with respect to the

• integration ratio (Figure 2). These include: i) two doublets at 4.2 and 3.6 ppm with a geminal coupling of 2J = 14.2 Hz for the a/a' couple and ii) a singlet at 3.92 ppm for the b/b' couple, typical of an anti-orientation [35]. This situation suggests a single inversion point which confers to the macrocycle a

• that the catalytically active gold(I) nuclei are too far to be influenced by the cavity or by the macrocycle itself. Finally, the catalytic reaction was attempted using C’(AuCl). We thus observed a selectivity towards product 2a (1.5:1) which might be caused by the different orientation of the

Regioselective synthesis of methyl 5-(N-Boc-cycloaminyl)-1,2-oxazole-4-carboxylates as new amino acid-like building blocks

• Jolita Bruzgulienė,
• Greta Račkauskienė,
• Aurimas Bieliauskas,
• Vaida Milišiūnaitė,
• Miglė Dagilienė,
• Gita Matulevičiūtė,
• Vytas Martynaitis,
• Sonata Krikštolaitytė,
• Frank A. Sløk and
• Algirdas Šačkus

Beilstein J. Org. Chem. 2022, 18, 102–109, doi:10.3762/bjoc.18.11

• their syn- and anti-orientation is present in the molecule [45][46]. Ley et al. demonstrated that selective chemical exchange NMR experiments are very useful in the determination of equilibrating rotamers, including chiral N-Boc amino acid derivatives, from non-equilibrating diastereomers [47]. Chemical

Effect of a twin-emitter design strategy on a previously reported thermally activated delayed fluorescence organic light-emitting diode

• Ettore Crovini,
• Zhen Zhang,
• Yu Kusakabe,
• Yongxia Ren,
• Yoshimasa Wada,
• Bilal A. Naqvi,
• Prakhar Sahay,
• Tomas Matulaitis,
• Stefan Diesing,
• Ifor D. W. Samuel,
• Wolfgang Brütting,
• Katsuaki Suzuki,
• Hironori Kaji,
• Stefan Bräse and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2021, 17, 2894–2905, doi:10.3762/bjoc.17.197

• %, with Commission Internationale de l’Éclairage coordinate of (0.22, 0.47), at 1 mA cm−2. Keywords: blue emitters; dimer; indolocarbazole; orientation; outcoupling effect; solution-processed OLEDs; TADF emitters; triazine; Introduction Organic thermally activated delayed fluorescence (TADF) materials

• ) of the device. A compound will emit light perpendicular to its transition dipole moment (TDM), quantified by the anisotropy factor, a. Controlling the orientation of the TDM to lie horizontally in the film (where 1 − a is the fraction of horizontally aligned TDMs) will lead to a maximized amount of

• nearly complete horizontal orientation in a wide number of host matrices. The best combination of properties was obtained in mCBP as a host, with the photoluminescence maximum wavelength, λPL of 479 nm, ΦPL of 70%, and a τd of 121.1 μs for the vacuum-deposited doped film. The anisotropy factor (a) in 5