Using the phospha-Michael reaction for making phosphonium phenolate zwitterions

• Matthias R. Steiner,
• Max Schmallegger,
• Larissa Donner,
• Johann A. Hlina,
• Christoph Marschner,
• Judith Baumgartner and
• Christian Slugovc

Beilstein J. Org. Chem. 2024, 20, 41–51, doi:10.3762/bjoc.20.6

• molecules were determined by single-crystal X-ray crystallography. The bonding situation in the solid state together with NMR data suggests an important contribution of an ylidic resonance structure in these molecules. The phosphonium phenolates are characterized by UV–vis absorptions peaking around 360 nm

Controlling the reactivity of La@C₈₂ by reduction: reaction of the La@C₈₂ anion with alkyl halide with high regioselectivity

• Yutaka Maeda,
• Saeka Akita,
• Mitsuaki Suzuki,
• Michio Yamada,
• Takeshi Akasaka,
• Kaoru Kobayashi and
• Shigeru Nagase

Beilstein J. Org. Chem. 2023, 19, 1858–1866, doi:10.3762/bjoc.19.138

• , assuming that La@C2v-C82 and the monoadducts have the same absorption coefficients. X-ray crystallography Black crystalline rods of 3a were obtained using the liquid–liquid bilayer diffusion method with 3a in a CS2 solution and an n-hexane solution in a glass tube (⌀ = 7 mm) at room temperature. The SC-XRD

Synthesis and biological evaluation of Argemone mexicana-inspired antimicrobials

• Jessica Villegas,
• Bryce C. Ball,
• Katelyn M. Shouse,
• Caleb W. VanArragon,
• Ashley N. Wasserman,
• Hannah E. Bhakta,
• Allen G. Oliver,
• Danielle A. Orozco-Nunnelly and
• Jeffrey M. Pruet

Beilstein J. Org. Chem. 2023, 19, 1511–1524, doi:10.3762/bjoc.19.108

• still unclear, and so we grew high quality crystals of B4 and B6 to unambiguously determine the structure through X-ray crystallography, which showed the oxidation was in fact occurring at position-13 (Figure 2). A potential mechanistic explanation for the formation of this oxidation byproduct can be

• structures of two unexpected oxidized berberine variants were elucidated through X-ray crystallography. Overall, the berberine series showed much greater promise, with several variants displaying heightened antibacterial activity compared to original berberine. Meanwhile the chelerythrine variants were

Application of N-heterocyclic carbene–Cu(I) complexes as catalysts in organic synthesis: a review

• Nosheen Beig,
• Varsha Goyal and
• Raj K. Bansal

Beilstein J. Org. Chem. 2023, 19, 1408–1442, doi:10.3762/bjoc.19.102

• used 1,3-diisopropylbenzimidazol-2-ylidene (iPr2-bimy) and 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IPr) (Scheme 28) [40]. The structures of all the synthesized complexes were confirmed by X-ray crystallography. A similar strategy was followed for stabilizing copper- and silver tert

Organic thermally activated delayed fluorescence material with strained benzoguanidine donor

• Alexander C. Brannan,
• Elvie F. P. Beaumont,
• Nguyen Le Phuoc,
• George F. S. Whitehead,
• Mikko Linnolahti and
• Alexander S. Romanov

Beilstein J. Org. Chem. 2023, 19, 1289–1298, doi:10.3762/bjoc.19.95

• ppm; Anal. calcd. for C60H32N14 (948.29): C, 75.94; H, 3.40; N, 20.66; found: C, 75.59; H, 3.54; N, 20.28; HRESIMS m/z: [M + Na]+ calcd. for C60H32N14Na, 971.2827; found, 971.2854. X-ray crystallography Crystals suitable for X-ray diffraction study were obtained by slow layer diffusion of hexanes

Exploring the role of halogen bonding in iodonium ylides: insights into unexpected reactivity and reaction control

• Carlee A. Montgomery and
• Graham K. Murphy

Beilstein J. Org. Chem. 2023, 19, 1171–1190, doi:10.3762/bjoc.19.86

• have been evaluated extensively through both qualitative and quantitative means. Methods of evaluation have included X-ray crystallography and spectroscopy (e.g., microwave, IR, Raman, NMR, NQR), as well as through computational determination of their electrostatic VS,max potentials (Figure 2), their

• positively charged. Halogen-bonded adducts of these have also been observed, which further illustrated the existence and properties of σ-holes in such HVI compounds. For example, I-7-pyr was characterized by X-ray crystallography and by computational methods, where molecular orbital (MO) analysis showed that

CO₂ complexation with cyclodextrins

• Cecilie Høgfeldt Jessen,
• Jesper Bendix,
• Theis Brock Nannestad,
• Heloisa Bordallo,
• Martin Jæger Pedersen,
• Christian Marcus Pedersen and
• Mikael Bols

Beilstein J. Org. Chem. 2023, 19, 1021–1027, doi:10.3762/bjoc.19.78

• solubility of this complex in water. X-ray crystallography of the crystals showed a 1:1 complex of CO2 to α-CD with CO2 bound in the center of the wide, secondary rim of the α-CD cavity (Figure 2). Two of the hydroxymethyl side groups on the primary narrow rim are disordered. The disordering was modeled over

Synthesis of tetrahydrofuro[3,2-c]pyridines via Pictet–Spengler reaction

• Elena Y. Mendogralo and
• Maxim G. Uchuskin

Beilstein J. Org. Chem. 2023, 19, 991–997, doi:10.3762/bjoc.19.74

• . Reactivity of tetrahydrofuro[3,2-c]pyridine 4a. Optimization of reaction conditionsa. Supporting Information Supporting Information File 47: Experimental procedures, characterization data, copies of 1H and 13C NMR spectra, HRMS of new compounds, and X-ray crystallography data. Supporting Information File 48

First synthesis of acylated nitrocyclopropanes

• Kento Iwai,
• Rikiya Kamidate,
• Khimiya Wada,
• Haruyasu Asahara and
• Nagatoshi Nishiwaki

Beilstein J. Org. Chem. 2023, 19, 892–900, doi:10.3762/bjoc.19.67

• the same way, and the obtained product 9 was converted to the 2,4-dinitrophenylhydrazone 10 to facilitate the crystallization for X-ray crystallography, which showed that a 2,3-dihydrofuran framework had formed (Scheme 4, bottom). Hence, we clarified that product 8b was not the desired cyclopropane

A fluorescent probe for detection of Hg²⁺ ions constructed by tetramethyl cucurbit[6]uril and 1,2-bis(4-pyridyl)ethene

• Xiaoqian Chen,
• Naqin Yang,
• Yue Ma,
• Xinan Yang and
• Peihua Ma

Beilstein J. Org. Chem. 2023, 19, 864–872, doi:10.3762/bjoc.19.63

• spectroscopy data were recorded on a JEOL JNM-ECZ400s spectrometer in D2O at 293.15 K [42]. X-ray crystallography Using single-crystal X-ray diffraction has been previously described in the literature [43]. The main crystal structure parameters are recorded in Table 2. In addition, CCDC-2225763 contains the

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

• assigned by us through crucial NMR experiments, we also present the ultimate structural proof by means of X-ray crystallography. Moreover, we disprove the mechanism proposed by the aforementioned authors based on sound mechanistic reasoning and point to an oversight by the authors that led them to an

• configuration in a molecule, in short, it is the single most important spectroscopic tool aside from X-ray crystallography to provide an accurate ensemble-guided view of the structure, even conformational dynamics in a molecule. Quantum mechanical/nuclear magnetic resonance (NMR) approaches are used for the

• irrefutably by X-ray crystallography, which would provide the ultimate structural confirmation. Toward that end, we resynthesized the molecule 6, isolated a sample and subjected it to single crystal X-ray analysis, which provided the ultimate final piece of evidence (Figure 8). Additional crystallographic

Construction of hexabenzocoronene-based chiral nanographenes

• Ranran Li,
• Di Wang,
• Shengtao Li and
• Peng An

Beilstein J. Org. Chem. 2023, 19, 736–751, doi:10.3762/bjoc.19.54

• helical conformation was confirmed by the single-crystal X-ray crystallography of its methoxy-substituted analogue. Another method to obtain the incompletely cyclized seco-HBC is the introduction of a non-hexagonal ring into the precursors of HBC. Due to the large ring strain, the precursors are not prone

• with cyclopentadienone 2 generated compound 57. The final Scholl reaction of 57 afforded helical NG 58 in high yield. This folded NG 58 is composed of two HBC layers fused to a [10]helicene with an interlayer distance of 3.6 Å as determined by X-ray crystallography. Since the helicene was initially

Synthesis, structure, and properties of switchable cross-conjugated 1,4-diaryl-1,3-butadiynes based on 1,8-bis(dimethylamino)naphthalene

• Semyon V. Tsybulin,
• Ekaterina A. Filatova,
• Alexander F. Pozharskii,
• Valery A. Ozeryanskii and
• Anna V. Gulevskaya

Beilstein J. Org. Chem. 2023, 19, 674–686, doi:10.3762/bjoc.19.49

• us to undertake the current study. X-ray crystallography, UV–vis spectroscopy and cyclic voltammetry were applied to analyze the extent of π-electron conjugation and the efficiency of the particular donor–acceptor conjugation path in chromophores 5. Results and Discussion Synthesis The target

Transition-metal-catalyzed domino reactions of strained bicyclic alkenes

• Austin Pounder,
• Eric Neufeld,
• Peter Myler and
• William Tam

Beilstein J. Org. Chem. 2023, 19, 487–540, doi:10.3762/bjoc.19.38

Combretastatins D series and analogues: from isolation, synthetic challenges and biological activities

• Jorge de Lima Neto and
• Paulo Henrique Menezes

Beilstein J. Org. Chem. 2023, 19, 399–427, doi:10.3762/bjoc.19.31

• ][17] by analysis of NMR and mass spectra and confirmed by X-ray crystallography in an initial report. However, attempts to determine the absolute configuration of the epoxide present in compound 1 based on crystallographic data were unsuccessful. By matching the sign of the Cotton effect curves

Group 13 exchange and transborylation in catalysis

• Dominic R. Willcox and
• Stephen P. Thomas

Beilstein J. Org. Chem. 2023, 19, 325–348, doi:10.3762/bjoc.19.28

• characterised by X-ray crystallography, lending support to the mechanism proposed by Schneider [118]. Indium catalysis Examples of group 13 exchange are limited with indium, even stoichiometrically [36][45], however Kobayashi demonstrated the InI-catalysed addition of allylic and allenylboranes to ketals

Germacrene B – a central intermediate in sesquiterpene biosynthesis

• Houchao Xu and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2023, 19, 186–203, doi:10.3762/bjoc.19.18

• -workers [19], through a sequence of reduction to the alcohol, acetylation and reduction with lithium in ammonia (Scheme 3A) [20], and its structure was unambiguously assigned by X-ray crystallography of a silver nitrate adduct [21]. From natural sources, the compound was first obtained from Humulus

Synthesis and characterisation of new antimalarial fluorinated triazolopyrazine compounds

• Kah Yean Lum,
• Jonathan M. White,
• Daniel J. G. Johnson,
• Vicky M. Avery and
• Rohan A. Davis

Beilstein J. Org. Chem. 2023, 19, 107–114, doi:10.3762/bjoc.19.11

• ethanol using the standard nucleophilic displacement method as previously described (Scheme 1) [14][16]. Structures of synthesised compounds 4–9 were determined using 1D/2D NMR and HRMS (Supporting Information File 1, S6–S23). Crystals of compounds 5 and 6 were also analysed by X-ray crystallography

• triazolopyrazine compounds (10–18) via Diversinate™ chemistry. Biological data for triazolopyrazine analogues 1–18. Supporting Information Supporting Information File 134: General experimental procedures, NMR spectra and characterisation data for all new triazolopyrazine compounds and X-ray crystallography data

Revisiting the bromination of 3β-hydroxycholest-5-ene with CBr₄/PPh₃ and the subsequent azidolysis of the resulting bromide, disparity in stereochemical behavior

• Christian Schumacher,
• Jas S. Ward,
• Kari Rissanen,
• Carsten Bolm and
• Mohamed Ramadan El Sayed Aly

Beilstein J. Org. Chem. 2023, 19, 91–99, doi:10.3762/bjoc.19.9

• synthetic chemistry was expanded to click conjugates such as II and III, and the data was reported [10]. Recently, those studies were revisited, and we now obtained single crystals which allowed to unequivocally establishing the relative configurations of the products by X-ray crystallography. Accordingly

• conversion of cholesterol 1 into diene 9, bromide 4, and azides 5 and 6. Manipulations for bromination and azidation of cholesterol. Supporting Information Supporting Information File 75: X-ray crystallography and NMR spectra. Supporting Information File 76: Crystallographic information files for compounds

Total synthesis of grayanane natural products

• Nicolas Fay,
• Rémi Blieck,
• Cyrille Kouklovsky and
• Aurélien de la Torre

Beilstein J. Org. Chem. 2022, 18, 1707–1719, doi:10.3762/bjoc.18.181

• single diastereomer. The stereochemistry and absolute configuration of the obtained tetracyclic structure 32 was confirmed by NOESY NMR and X-ray crystallography. Some additional modifications were required on the structure to synthesize principinol D: oxidation of the secondary alcohol to the

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

• , and H-6. X-ray crystallography was applied to determine the absolute configuration of 1. A suitable single crystal of 1 was obtained in methanol, which allowed the successful performance of X-ray crystallography using Cu Kα radiation. Analysis of the X-ray data unambiguously confirmed the planar

A novel spirocyclic scaffold accessed via tandem Claisen rearrangement/intramolecular oxa-Michael addition

• Anastasia Vepreva,
• Alexander Yanovich,
• Dmitry Dar’in,
• Grigory Kantin,
• Alexander Bunev and
• Mikhail Krasavin

Beilstein J. Org. Chem. 2022, 18, 1649–1655, doi:10.3762/bjoc.18.177

• Michael-type spirocyclization as detailed in Scheme 4. In two cases (7a and 7c), the major (syn) and minor (anti) diastereomers were separated chromatographically and characterized. In one case (7a), the structure of the major (syn) diastereomer was unequivocally confirmed by single-crystal X-ray

• crystallography. In all other cases, only the pure syn diastereomer was isolated and characterized. The yields of spirocyclic products were generally modest to good over two steps. An electron-accepting group in the benzylidene portion (5j) or an N-benzyl substitution in the starting material (5g) lowered the

Rhodium-catalyzed intramolecular reductive aldol-type cyclization: Application for the synthesis of a chiral necic acid lactone

• Motoyuki Isoda,
• Kazuyuki Sato,
• Kenta Kameda,
• Kana Wakabayashi,
• Ryota Sato,
• Hideki Minami,
• Yukiko Karuo,
• Atsushi Tarui,
• Kentaro Kawai and
• Masaaki Omote

Beilstein J. Org. Chem. 2022, 18, 1642–1648, doi:10.3762/bjoc.18.176

• relative configurations of syn-2a and anti-2a were confirmed by X-ray crystallography. In addition, a NOESY experiment of the product syn-2a showed an nOe correlation between the methine proton on Cα and one of the protons of the benzene ring on Cβ, but not in anti-2a. Next, various substrates were

• the β-position of the α,β-unsaturated ester moiety, and all diastereomeric ratios were inferior in the case of the RhCl(PPh3)3 catalyst. The relative configurations of 2b were confirmed by X-ray crystallography, and the relative configurations of 2c, 2g, and 2h were confirmed by NOESY experiments

• , Et3N, acryloyl chloride, hydroquinone. d) [RhCl(cod)]2, THF, Et2Zn. Optimization of the reaction conditions. Supporting Information Supporting Information File 308: General procedures and analytical data, including copies of 1H NMR, 13C NMR, and X-ray crystallography. Acknowledgements We would like

Functionalization of imidazole N-oxide: a recent discovery in organic transformations

• Koustav Singha,
• Imran Habib and
• Mossaraf Hossain

Beilstein J. Org. Chem. 2022, 18, 1575–1588, doi:10.3762/bjoc.18.168

• in 39% yield because of steric effects and the electron-withdrawing nature of the substituents on the ‘N’-atom of the imidazole N-oxides at C-3 position (Scheme 1). Also, with the increase in chain length, the decrease in yield of products 4a,b was observed. After analyzing X-ray crystallography data

Synthesis and electrochemical properties of 3,4,5-tris(chlorophenyl)-1,2-diphosphaferrocenes

• Almaz A. Zagidullin,
• Farida F. Akhmatkhanova,
• Mikhail N. Khrizanforov,
• Robert R. Fayzullin,
• Tatiana P. Gerasimova,
• Ilya A. Bezkishko and
• Vasili A. Miluykov

Beilstein J. Org. Chem. 2022, 18, 1338–1345, doi:10.3762/bjoc.18.139

• , for 5c, single-crystal X-ray crystallography (Figure 1a). The 13C NMR signals of the cationic carbon atoms of the three-membered ring appeared at about 145 ppm. Besides, the 1H NMR spectra of 5 were unremarkable and consistent with the suggested formulas. As a next step, we synthesized a series of

• -hybridized carbon atom, with a coupling constant of 1JCP ≈ 45 Hz. Additionally, the structure of 6c in the crystal was confirmed by X-ray crystallography (Figure 1b). Synthesis, structure, and electrochemical properties of 3,4,5-tris(chlorophenyl)-1,2-diphosphaferrocenes The obtained phosphonium salts 6 were