Metal-free synthesis of phosphinoylchroman-4-ones via a radical phosphinoylation–cyclization cascade mediated by K₂S₂O₈

• Qiang Liu,
• Weibang Lu,
• Guanqun Xie and
• Xiaoxia Wang

Beilstein J. Org. Chem. 2020, 16, 1974–1982, doi:10.3762/bjoc.16.164

• (Table 1, entry 1). The structure of 3aa was unambiguously confirmed by X-ray diffraction analysis of a single crystal (Figure 2) and by NMR spectroscopy (see Supporting Information File 1) [33]. The increase of the amount of K2S2O8 to 3 equiv resulted in the improvement of the yield of 3aa to 52% (Table

• the optimized conditions (Scheme 4). The reaction afforded the desired product 3ba in a good yield of 56%, and the structure was also confirmed by X-ray diffraction (see Supporting Information File 1) [33]. To gain an insight into the reaction mechanism, we carried out some control experiments (Scheme

Synthesis of 3(2)-phosphonylated thiazolo[3,2-a]oxopyrimidines

• Ksenia I. Kaskevich,
• Anastasia A. Babushkina,
• Vladislav V. Gurzhiy,
• Dmitrij M. Egorov,
• Nataly I. Svintsitskaya and
• Albina V. Dogadina

Beilstein J. Org. Chem. 2020, 16, 1947–1954, doi:10.3762/bjoc.16.161

• thiazolopyrimidine-5-ones by reacting 6-methyl-2-thiouracils with bromoethynylketones has been reported by Shishkin and co-workers (Scheme 4) [20]. The authors for the first time proved the structure of the 5-oxo isomer by single crystal X-ray diffraction analysis. The Pd-catalyzed Sonogashira coupling reaction

• those for 3-phenylthiazolo[3,2-a]-5-oxopyrimidine [40]. In addition, the structures of the phosphonylated thiazolopyrimidines 3a and 3d were unambiguously confirmed by single crystal X-ray diffraction data. The presence of the CH3 group at the position 5 of the thiouracil ring changes the reaction

• NMR spectroscopy. In the 13C NMR spectra of the thiazolopyrimidines 6a–c, the O=C–CH=CH fragment is observed by signals of equal intensity at δC 112–113 and 135–136 ppm. However, the unambiguous proof of the structure of thiazolopyrimidine-7-one 6b was obtained by single crystal X-ray diffraction

Selective preparation of tetrasubstituted fluoroalkenes by fluorine-directed oxetane ring-opening reactions

• Clément Q. Fontenelle,
• Thibault Thierry,
• Romain Laporte,
• Emmanuel Pfund and
• Thierry Lequeux

Beilstein J. Org. Chem. 2020, 16, 1936–1946, doi:10.3762/bjoc.16.160

• major isomer were obtained by recrystallization. The X-ray diffraction analysis clearly showed that the bromine atom was located on the carbon trans to the fluorine atom resulting in the major product with the E-geometry (see Supporting Information File 1). It should be noted that longer reaction times

• ]. Pleasingly, when subjecting compound 4 to the previous reaction conditions, a single isomer of bromoalcohol 4d formed (determined by 1H NMR of the crude) and the product was isolated in an excellent yield of 94% (Table 2, entry 3). The geometry of the product was confirmed to be E-4d by X-ray diffraction

On the hydrolysis of diethyl 2-(perfluorophenyl)malonate

• Ilya V. Taydakov and
• Mikhail A. Kiskin

Beilstein J. Org. Chem. 2020, 16, 1863–1868, doi:10.3762/bjoc.16.153

• File 1). The structure of acid 12 in solid form was studied by single crystal X-ray diffraction experiments (Figure 3). The structural parameters were deposited at CCDC (deposit No. 1993963, see Supporting Information File 1 for details). Since basic conditions seem to be unsuitable for the hydrolysis

• Supporting Information File 148: Detailed information about experimental procedures, X-ray diffraction experiments for compound 12 and characterization data for compounds 3 and 12. Acknowledgements Single crystal X-ray diffraction analysis was performed using the equipment at the Centre for Collective Use

Synthesis and highly efficient light-induced rearrangements of diphenylmethylene(2-benzo[b]thienyl)fulgides and fulgimides

• Vladimir P. Rybalkin,
• Sofiya Yu. Zmeeva,
• Lidiya L. Popova,
• Valerii V. Tkachev,
• Andrey N. Utenyshev,
• Olga Yu. Karlutova,
• Alexander D. Dubonosov,
• Vladimir A. Bren,
• Sergey M. Aldoshin and
• Vladimir I. Minkin

Beilstein J. Org. Chem. 2020, 16, 1820–1829, doi:10.3762/bjoc.16.149

• -isomers and of products of the photoinduced rearrangement completed by 1,5-H shift reaction, 3a,4-dihydronaphtho[2,3-c]furans(pyrroles) C, were established based on the data of 1H and 13C NMR spectroscopy and X-ray diffraction studies. Keywords: benzo[b]thiophene; fulgide; fulgimide; photorearrangement

• ; X-ray diffraction; Introduction Photochromic compounds are of considerable interest as molecular switches, elements of optical memory and molecular logic devices [1][2][3][4]. Fulgides and fulgimides possessing excellent thermal and photochemical stability, structurally modulated fluorescent

• afford exclusively fulgimides 3Z and 7E, respectively, as the single products (Scheme 2 and Scheme 3). According to IR, 1H and 13C NMR spectroscopy data Z- and E-isomers of fulgide 3 exist in the form of the open isomers O. This was also confirmed by X-ray diffraction study. The molecular structures of

Microwave-assisted efficient one-pot synthesis of N²-(tetrazol-5-yl)-6-aryl/heteroaryl-5,6-dihydro-1,3,5-triazine-2,4-diamines

• Moustafa Sherief Moustafa,
• Ramadan Ahmed Mekheimer,
• Saleh Mohammed Al-Mousawi,
• Mohamed Abd-Elmonem,
• Hesham El-Zorba,
• Afaf Mohamed Abdel Hameed,
• Tahany Mahmoud Mohamed and
• Kamal Usef Sadek

Beilstein J. Org. Chem. 2020, 16, 1706–1712, doi:10.3762/bjoc.16.142

• unequivocally supported by single-crystal X-ray diffraction (Figure 1 and Table 2). A plausible mechanism for the formation of products 4 is postulated in Scheme 3. The dimerization of cyanamide 1 in basic medium to cyanoguanidine 5 and subsequent reaction with 5-aminotetrazole (3) yielded tetrazolylbiguanidine

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

• previous deprotection reactions, fluorene 21 was converted by means of a three-step sequence to the desired azide-functionalized 7-bromofluorene-2-carbaldehyde 5 in 86% yield and an overall yield of 45% (starting from fluorene). The molecular structure of 5 could be verified by X-ray diffraction (XRD, see

Rearrangement of o-(pivaloylaminomethyl)benzaldehydes: an experimental and computational study

• Csilla Hargitai,
• Györgyi Koványi-Lax,
• Tamás Nagy,
• Péter Ábrányi-Balogh,
• András Dancsó,
• Gábor Tóth,
• Judit Halász,
• Angéla Pandur,
• Gyula Simig and
• Balázs Volk

Beilstein J. Org. Chem. 2020, 16, 1636–1648, doi:10.3762/bjoc.16.136

• ) coupled with a Dionex Ultimate 3000 RS HPLC (Sunnyvale, CA, USA) system with a diode array detector. HRMS spectra of the diastereomeric 23a and 23b compounds are shown on page S44 of Supporting Information File 1. Single-crystal X-ray diffraction (SC-XRD) measurements were carried out on a Rigaku R-Axis

Fluorohydration of alkynes via I(I)/I(III) catalysis

• Jessica Neufeld,
• Constantin G. Daniliuc and
• Ryan Gilmour

Beilstein J. Org. Chem. 2020, 16, 1627–1635, doi:10.3762/bjoc.16.135

• established by single crystal X-ray diffraction (Figure 2). Interestingly, a study by Pattison has established that α-fluoroketones preferentially adopt a cis-conformation in polar solvents [54]. In the solid state, a dihedral angle of φ = −3.7° was observed thereby placing the C–F bond in the same plane as

Five-component, one-pot synthesis of an electroactive rotaxane comprising a bisferrocene macrocycle

• Natalie Lagesse,
• Luca Pisciottani,
• Maxime Douarre,
• Pascale Godard,
• Brice Kauffmann,
• Vicente Martí-Centelles and
• Nathan D. McClenaghan

Beilstein J. Org. Chem. 2020, 16, 1564–1571, doi:10.3762/bjoc.16.128

• structure of rotaxane 1a was determined by single crystal X-ray diffraction of crystals obtained by slow evaporation of a dichloromethane solution. The analysis of the X-ray solid-state structure of the rotaxane 1a showed a significant difference to Leigh’s rotaxane I [4]. Rotaxane I only presented two

One-pot synthesis of 1,3,5-triazine-2,4-dithione derivatives via three-component reactions

• Gui-Feng Kang and
• Gang Zhang

Beilstein J. Org. Chem. 2020, 16, 1447–1455, doi:10.3762/bjoc.16.120

• structures of 1,3,5-triazine-2,4-dithione derivatives were characterized by spectroscopic techniques as well as by single crystal X-ray diffraction. Keywords: aldehydes; multicomponent reactions; nitrogen heterocycles; thiourea; triazinethiones; Introduction The construction of nitrogen-containing

• structure unambiguously, as a representative example, the structure of 6aa was also confirmed by single crystal X-ray diffraction (XRD) studies after crystallization from ethyl acetate/hexane (Figure 2). CCDC 1991859 (for 6aa) contains the supplementary crystallographic data for this paper. These data are

Highly selective Diels–Alder and Heck arylation reactions in a divergent synthesis of isoindolo- and pyrrolo-fused polycyclic indoles from 2-formylpyrrole

• Carlos H. Escalante,
• Eder I. Martínez-Mora,
• Carlos Espinoza-Hicks,
• Alejandro A. Camacho-Dávila,
• Fernando R. Ramos-Morales,
• Francisco Delgado and
• Joaquín Tamariz

Beilstein J. Org. Chem. 2020, 16, 1320–1334, doi:10.3762/bjoc.16.113

• natural pyrrolizine- and isoindole-containing alkaloids. Structures of 9m (a) and 10m (b) as determined by single-crystal X-ray diffraction crystallography (ellipsoids at the 30% probability level). M06-2X/6-31+G(d,p) Optimized geometry for each of the SCs (a and d), TSs (b and e) and ADs (c and f) of the

• isomer 10m, the irradiation of the singlet of the methyl group of the C-4 acetyl group increased the size of the signals of the protons H-3a and H-8b, which are located on the same side as the acetyl group. The unambiguous assignment of their structures was accomplished by a single-crystal X-ray

• diffraction crystallography of both endo 9m and exo 10m adducts (Figure 2) [43]. In addition, the thermal cycloadditions of 2-vinylpyrroles 8a–j and maleimides 7b,c took place satisfactorily to deliver the expected adducts 9e–p/10e–p, also with high endo diastereoselectivity and good yields (Table 2, entries

Ferrocenyl-substituted tetrahydrothiophenes via formal [3 + 2]-cycloaddition reactions of ferrocenyl thioketones with donor–acceptor cyclopropanes

• Grzegorz Mlostoń,
• Mateusz Kowalczyk,
• André U. Augustin,
• Peter G. Jones and
• Daniel B. Werz

Beilstein J. Org. Chem. 2020, 16, 1288–1295, doi:10.3762/bjoc.16.109

• were formed with complete diastereoselectivity, leading to a single isomer. In order to establish the structure of the isomers, a single crystal obtained for compound 9c was studied by X-ray diffraction analysis which showed, that the Ph(C-2) group and Fc(C-5) substituent were mutually cis-oriented

• the slightly more polar one was isolated and identified as the minor isomer of 9d. In the course of crystallization from hexane the less polar fraction gave single crystals suitable for the X-ray diffraction analysis, which unambiguously confirmed that in this molecule the Ph(C-5) and Fc(C-2) groups

Synthesis, antiinflammatory activity, and molecular docking studies of bisphosphonic esters as potential MMP-8 and MMP-9 inhibitors

• Abimelek Cortes-Pacheco,
• María Adelina Jiménez-Arellanes,
• Francisco José Palacios-Can,
• José Antonio Valcarcel-Gamiño,
• Rodrigo Said Razo-Hernández,
• María del Carmen Juárez-Vázquez,
• Adolfo López-Torres and
• Oscar Abelardo Ramírez-Marroquín

Beilstein J. Org. Chem. 2020, 16, 1277–1287, doi:10.3762/bjoc.16.108

• , angiogenesis, and metastasis in cancer [12][13][14][15], pointing at bisphosphonates as potential treatments for cancer and other inflammation-related diseases. In this respect, MMP inhibition by phosphonates or bisphosphonates has been previously studied through computational or X-ray diffraction analyses to

• are well known. For example, the coordination of the P=O oxygen atom in bisphosphonates with a zinc cation in the catalytic site of the MMPs has been characterized, both through X-ray diffraction and molecular docking studies [11][36][37]. Consequently, we propose MMP-8 and MMP-9 as potential

Oxime radicals: generation, properties and application in organic synthesis

• Igor B. Krylov,
• Stanislav A. Paveliev,
• Alexander S. Budnikov and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2020, 16, 1234–1276, doi:10.3762/bjoc.16.107

• C-centered radical 125 by TBN [130]. Intermediate 127 was isolated in 96% yield and its structure was confirmed by a single-crystal X-ray diffraction. Under the action of Et3N, the dimeric nitroso compound 127 was converted into the more stable oxime tautomeric form 123a (Scheme 41). Another

Activated carbon as catalyst support: precursors, preparation, modification and characterization

• Melanie Iwanow,
• Tobias Gärtner,
• Volker Sieber and
• Burkhard König

Beilstein J. Org. Chem. 2020, 16, 1188–1202, doi:10.3762/bjoc.16.104

• phosphorous species in the carbons could be responsible for the examined difference [130]. X-ray diffraction (XRD): X-ray diffraction gives information on the crystallinity or amorphicity of activated carbons. Comparison of resulting XRD patterns with the crystallographic databases clarify that partially

The charge-assisted hydrogen-bonded organic framework (CAHOF) self-assembled from the conjugated acid of tetrakis(4-aminophenyl)methane and 2,6-naphthalenedisulfonate as a new class of recyclable Brønsted acid catalysts

• Svetlana A. Kuznetsova,
• Alexander S. Gak,
• Yulia V. Nelyubina,
• Vladimir A. Larionov,
• Han Li,
• Michael North,
• Vladimir P. Zhereb,
• Alexander F. Smol'yakov,
• Artem O. Dmitrienko,
• Michael G. Medvedev,
• Igor S. Gerasimov,
• Ashot S. Saghyan and
• Yuri N. Belokon

Beilstein J. Org. Chem. 2020, 16, 1124–1134, doi:10.3762/bjoc.16.99

• 2,6-naphthalenedisulfonate (NDS, 2 equivalents) and the tetrahydrochloride salt of tetrakis(4-aminophenyl)methane (TAPM, 1 equivalent) in water gave a novel three-dimensional charge-assisted hydrogen-bonded framework (CAHOF, F-1). The framework F-1 was characterized by X-ray diffraction, TGA

• organic framework F-1. The structure of F-1 was established by single crystal and powder X-ray diffraction, NMR spectroscopy, and elemental analysis. The morphology of F-1 was assessed by SEM, and its stability was determined by TGA. We report the use of F-1 as a heterogeneous, robust, and recoverable

• structure as depicted in Scheme 1. A crystal of the compound was grown by diffusion of water into a solution of F-1 in DMSO. The results of the X-ray diffraction analysis are shown in Figure 1. The single crystal material of F-1 (F-1a phase) was in the monoclinic space group P21/c, with the lattice

Synthesis of esters of diaminotruxillic bis-amino acids by Pd-mediated photocycloaddition of analogs of the Kaede protein chromophore

• Esteban P. Urriolabeitia,
• Pablo Sánchez,
• Alexandra Pop,
• Cristian Silvestru,
• Eduardo Laga,
• Ana I. Jiménez and
• Carlos Cativiela

Beilstein J. Org. Chem. 2020, 16, 1111–1123, doi:10.3762/bjoc.16.98

• emitting diodes (LEDs) were purchased from Topbright. X-ray crystallography Single crystals of 2c and 4a of suitable quality for X-ray diffraction measurements were grown by slow diffusion of n-pentane into CH2Cl2 solutions of the crude product at –18 °C for several weeks. One selected single crystal was

Copper catalysis with redox-active ligands

• Agnideep Das,
• Yufeng Ren,
• Cheriehan Hessin and
• Marine Desage-El Murr

Beilstein J. Org. Chem. 2020, 16, 858–870, doi:10.3762/bjoc.16.77

• resulting copper complexes were synthesized and single crystal X-ray diffraction analysis evidenced the existence of H-bonding inside the coordination sphere of 6 (Scheme 3). The authors reported that the influence of the geometry of the complex on the H-bonding interactions as well as the nature of this

• . Strikingly, combination of these unique steric and electronic features results in a distorted pentacoordinated sphere exhibiting a newly occupied coordination site, as confirmed by single crystal X-ray diffraction analysis. This particular geometry results in enhanced catalytic reactivity and is clearly

One-pot synthesis of dicyclopenta-fused peropyrene via a fourfold alkyne annulation

• Ji Ma,
• Yubin Fu,
• Junzhi Liu and
• Xinliang Feng

Beilstein J. Org. Chem. 2020, 16, 791–797, doi:10.3762/bjoc.16.72

• -diphenylpyrene is the key step. The single crystal X-ray diffraction analysis revealed a twisted structure of 1 due to the steric hindrance at the bay positions. From the bond length analysis and DFT calculations, CP-PAH 1 consists of the aromatic peropyrene core with two slightly antiaromatic peri-fused five

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

• the tight packing observed for the homo π-stacking. Similarly, a mixture between the homo and hetero π-stacking would cause a more amorphous crystal and would be the least likely to form in a solid state a crystal suitable for determination by X-ray diffraction. The driving force for this crystal

• for C102H88N4O4Si2Zn, 1552.5636; found, 1552.5616. Crystal structure determinations Crystals were grown following the protocol developed by Hope by dissolving the compound in CH2Cl2 and layering with a MeOH for liquid–liquid diffusion [52]. Single crystal X-ray diffraction data for all compounds were

Efficient synthesis of dipeptide analogues of α-fluorinated β-aminophosphonates

• Marcin Kaźmierczak and
• Henryk Koroniak

Beilstein J. Org. Chem. 2020, 16, 756–762, doi:10.3762/bjoc.16.69

• at room temperature. What is more, we attempted to crystallize at least one derivative to confirm the absolute stereochemistry of the obtained compounds. In order to obtain a single crystal suitable for X-ray diffraction studies, various crystallization techniques were tested [37][38

• developing systems, and products were detected by inspection under UV light (254 nm) and with a solution of potassium permanganate. Merck Kieselgel 60 (0.063–0.200 μm), Merck Kieselgel 60 (0.040–0.063 μm), and Merck Kieselgel 60 (0.015–0.004 μm), were used for column chromatography. X-ray diffraction data

• . Supporting Information File 12: CIF file of 14c. Acknowledgements Marcin Kaźmierczak and Henryk Koroniak would like to thank Prof. Maciej Kubicki for X-ray diffraction analysis. Funding Marcin Kaźmierczak would like to thank the National Science Centre for financial support under grant 2018/02/X/ST5/02867

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

• for Scientific Research on Innovative Area “π Space Figuration” from MEXT (No. JP26102002), and JSPS KAKENHI (19H00912). The X-ray diffraction study of 5b with synchrotron radiation was performed at the Pohang Accelerator Laboratory (Beamline 2D) supported by POSTECH.

Direct borylation of terrylene and quaterrylene

• Haruka Kano,
• Keiji Uehara,
• Kyohei Matsuo,
• Hironobu Hayashi,
• Hiroko Yamada and
• Naoki Aratani

Beilstein J. Org. Chem. 2020, 16, 621–627, doi:10.3762/bjoc.16.58

• direct borylation of C–H bonds in terrylene in 56% yield. The product is soluble in common organic solvents and could be purified without column chromatography. Single crystal X-ray diffraction analysis revealed that the terrylene core is not disturbed by the substituents and is perfectly flat. The

• singlet peaks at 8.58, 8.37 and 8.23 ppm due to aromatic protons. The structure of TB4 was unambiguously revealed by single crystal X-ray diffraction analysis (Figure 2). The crystals suitable for X-ray diffraction were obtained by vapor diffusion of hexane into a solution of TB4 in CH2Cl2. The terrylene

Regioselectively α- and β-alkynylated BODIPY dyes via gold(I)-catalyzed direct C–H functionalization and their photophysical properties

• Takahide Shimada,
• Shigeki Mori,
• Masatoshi Ishida and
• Hiroyuki Furuta

Beilstein J. Org. Chem. 2020, 16, 587–595, doi:10.3762/bjoc.16.53

• of TIPS-ethynyl-substituted BODIPY derivatives 3–6 were characterized by 1H and 19F NMR spectroscopy, high-resolution mass spectrometry, and X-ray crystallographic analysis. The solid-state structures of the diethynyl-substituted BODIPYs were unambiguously elucidated by X-ray diffraction analysis (3a