Halide metathesis in overdrive: mechanochemical synthesis of a heterometallic group 1 allyl complex

• Ross F. Koby,
• Nicholas R. Rightmire,
• Nathan D. Schley,
• Timothy P. Hanusa and
• William W. Brennessel

Beilstein J. Org. Chem. 2019, 15, 1856–1863, doi:10.3762/bjoc.15.181

• produced crystals that were yellow-orange; they were highly soluble in C6D6, giving a bright red solution. Single crystal X-ray analysis identified the crystals as the heterometallic complex [KCsA'2] (see below). The 1H NMR spectrum of the products from the 1:1 and 3:1 grinds were identical. It should be

• analogous solvate is obtained, and the resulting crystals are of higher quality than those from toluene. Single crystal X-ray analysis reveals that it has a structure that is qualitatively the same as the toluene solvate, and only the benzene solvate is discussed here. Like the unsolvated complex [KA']∞ [17

Synthesis of pyrrolo[1,2-a]quinolines by formal 1,3-dipolar cycloaddition reactions of quinolinium salts

• Anthony Choi,
• Rebecca M. Morley and
• Iain Coldham

Beilstein J. Org. Chem. 2019, 15, 1480–1484, doi:10.3762/bjoc.15.149

• triethylamine and were pleased to obtain good yields of the adducts 7a–c and 8a,b (Scheme 2). In each case, the products 7a–c and 8a,b were formed as a single regioisomer and stereoisomer. The selectivity in favour of the isomer drawn in Scheme 2 was verified by single crystal X-ray analysis of the adduct 7c

• to undergo reaction with the ylides derived from the salts 4 and 5. In both cases, very good yields of the tetracyclic adducts 9 and 10 were obtained after heating for only 1 h (Scheme 3). The relative stereochemistry of the adduct 9 was determined by single crystal X-ray analysis (Figure 2). To

• with N-methylmaleimide in the presence of triethylamine in methanol to give the desired adducts 15a and 15b as single stereoisomers (Scheme 5). The stereochemistry of product 15a was confirmed by single crystal X-ray analysis (see Supporting Information File 1) and matches the relative configuration of

Selenophene-containing heterotriacenes by a C–Se coupling/cyclization reaction

• Pierre-Olivier Schwartz,
• Sebastian Förtsch,
• Astrid Vogt,
• Elena Mena-Osteritz and
• Peter Bäuerle

Beilstein J. Org. Chem. 2019, 15, 1379–1393, doi:10.3762/bjoc.15.138

• crucial cyclization steps to the stable and soluble fused systems were achieved by copper-catalyzed C–S and C–Se coupling/cyclization reactions. Structures and packing motifs in the solid state were elucidated by single crystal X-ray analysis and XRD powder measurements. Comparison of the optoelectronic

Mechanochemistry of supramolecules

• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2019, 15, 881–900, doi:10.3762/bjoc.15.86

• to be 100% stereospecific under dry mortar and pestle grinding [110]. The hydrogen-bond donor 4,6-dichlororesorcinol was used as the supramolecular catalyst for the transformation in the solid-state. From single crystal X-ray analysis the authors have proved the formation of the 2:2 complex 42 from

Synthesis of 2H-furo[2,3-c]pyrazole ring systems through silver(I) ion-mediated ring-closure reaction

• Vaida Milišiūnaitė,
• Rūta Paulavičiūtė,
• Eglė Arbačiauskienė,
• Vytas Martynaitis,
• Wolfgang Holzer and
• Algirdas Šačkus

Beilstein J. Org. Chem. 2019, 15, 679–684, doi:10.3762/bjoc.15.62

• −127.5 to −128.0 ppm for N-1. The structure of 4d was investigated additionally by single crystal X-ray analysis (Figure 1) [39]. The asymmetric unit of the crystal consists of two molecules 4d(A) and 4d(B) held together by the weak CH···N type hydrogen bonds C19–H···N51 (C···N = 3.470(11) Å, H···N

Annulation of 1H-pyrrole-2,3-diones by thioacetamide: an approach to 5-azaisatins

• Aleksandr I. Kobelev,
• Ekaterina E. Stepanova,
• Maksim V. Dmitriev and
• Andrey N. Maslivets

Beilstein J. Org. Chem. 2019, 15, 364–370, doi:10.3762/bjoc.15.32

• precipitates. The precipitates were isolated and analyzed. We established that they were formed by pyrrolo[3,2-c]pyridine-2,3-diones 4 (Scheme 3). The structure of compounds 4 was unequivocally confirmed by a single crystal X-ray analysis (CCDC 1877232). We assume that the formation of compounds 4 occurred

Nucleoside macrocycles formed by intramolecular click reaction: efficient cyclization of pyrimidine nucleosides decorated with 5'-azido residues and 5-octadiynyl side chains

• Jiang Liu,
• Peter Leonard,
• Sebastian L. Müller,
• Constantin Daniliuc and
• Frank Seela

Beilstein J. Org. Chem. 2018, 14, 2404–2410, doi:10.3762/bjoc.14.217

• new lead for a diversity of molecules. From the cyclic molecule a single crystal X-ray analysis was obtained. The sugar conformation was studied in solution and in solid state. Results and Discussion The octadiynyl derivative 1 of dC [32][33][34][35] was the starting material for the synthesis of 5

Some mechanistic aspects regarding the Suzuki–Miyaura reaction between selected ortho-substituted phenylboronic acids and 3,4,5-tribromo-2,6-dimethylpyridine

• Piotr Pomarański,
• Piotr Roszkowski,
• Jan K. Maurin,
• Armand Budzianowski and
• Zbigniew Czarnocki

Beilstein J. Org. Chem. 2018, 14, 2384–2393, doi:10.3762/bjoc.14.214

• determined on the basis of HT NMR and thermal epimerisation experiments. The structure of most presented atropisomeric derivatives of 2,6-dimethylpyridine was confirmed by single-crystal X-ray analysis. Racemic chiral, differently substituted atropisomers were also examined by 1H NMR spectroscopy in the

• chromatography using a specialist high-purity grade silica gel type H (10–40 µm). The structure of (syn)-10 was also confirmed by the single-crystal X-ray analysis (see Supporting Information File 1 for details). We also carried out a series of the cross-coupling reactions using 3,4-dibromo-5-(2-methoxyphenyl

Synthesis of 1,4-imino-L-lyxitols modified at C-5 and their evaluation as inhibitors of GH38 α-mannosidases

• Maroš Bella,
• Sergej Šesták,
• Ján Moncoľ,
• Miroslav Koóš and
• Monika Poláková

Beilstein J. Org. Chem. 2018, 14, 2156–2162, doi:10.3762/bjoc.14.189

• absolute configuration of carbamate 20 was confirmed by single-crystal X-ray analysis (Figure 2) [36]. Basic hydrolysis of carbamate 20 with 10% NaOH in refluxing EtOH provided aminoalcohol 21 which was subsequently N-benzylated with the corresponding benzyl bromides to yield pyrrolidines 22. Final

Synthesis of new tricyclic 5,6-dihydro-4H-benzo[b][1,2,4]triazolo[1,5-d][1,4]diazepine derivatives by [3⁺ + 2]-cycloaddition/rearrangement reactions

• Lin-bo Luan,
• Zi-jie Song,
• Zhi-ming Li and
• Quan-rui Wang

Beilstein J. Org. Chem. 2018, 14, 1826–1833, doi:10.3762/bjoc.14.155

• -jian Lin for structural confirmation of 10k and 13e by single-crystal X-ray analysis.

Synthesis of spirocyclic scaffolds using hypervalent iodine reagents

• Fateh V. Singh,
• Priyanka B. Kole,
• Saeesh R. Mangaonkar and
• Samata E. Shetgaonkar

Beilstein J. Org. Chem. 2018, 14, 1778–1805, doi:10.3762/bjoc.14.152

• ). Furthermore, the absolute configuration of 88 was assigned by its single crystal X-ray analysis. 3.3. Application of spirolactams in natural product synthesis In 2001, Ciufolini and co-workers [103] employed PIDA (15) as an electrophile during the synthesis of naturally occurring tricyclic azaspirane

An unusual thionyl chloride-promoted C−C bond formation to obtain 4,4'-bipyrazolones

• Gernot A. Eller,
• Gytė Vilkauskaitė,
• Algirdas Šačkus,
• Vytas Martynaitis,
• Ashenafi Damtew Mamuye,
• Vittorio Pace and
• Wolfgang Holzer

Beilstein J. Org. Chem. 2018, 14, 1287–1292, doi:10.3762/bjoc.14.110

• racemic mixture or the meso-form came into consideration. The single crystal X-ray analysis disclosed that the molecule of the newly obtained compound 3a consists of two pyrazolone residues, which are directly connected to each other by a single covalent carbon–carbon bond between the asymmetric sp3

Oxidative cycloaddition of hydroxamic acids with dienes or guaiacols mediated by iodine(III) reagents

• Hisato Shimizu,
• Akira Yoshimura,
• Keiichi Noguchi,
• Victor N. Nemykin,
• Viktor V. Zhdankin and
• Akio Saito

Beilstein J. Org. Chem. 2018, 14, 531–536, doi:10.3762/bjoc.14.39

• -alkylammonium periodates. To our delight, the sole use of DIB in a mixed solvent of DCM and methanol gave the endo-cycloadduct 6aa as a single regioisomer in 84% yield starting from hydroxamic acid 1a and guaiacol (5a, Scheme 2). The structure of 6aa was determined by single crystal X-ray analysis [24]. It

• X-ray analysis [24]. Next, we investigated the oxidative cycloaddition reactions of hydroxamic acids 1a–c with various dienes 2 under the optimal conditions (Table 2). Similarly to the benzoyl derivative 1a, the carbamate analogues 1b (R1 = OBn) and 1c (R1 = Ot-Bu) reacted with 1,3-cyclohexadiene

• test this hypothesis, the oxazine 3aa was treated with TfOH in DCM at 40 °C for 18 h and afforded 4 quantitatively. Furthermore, the TfOH-mediated formation of nitrone from such HDA adducts has been reported [23]. It should be mentioned that the structures of 3aa and 4 were determined by single crystal

Pyrene–nucleobase conjugates: synthesis, oligonucleotide binding and confocal bioimaging studies

• Artur Jabłoński,
• Yannic Fritz,
• Hans-Achim Wagenknecht,
• Rafał Czerwieniec,
• Tytus Bernaś,
• Damian Trzybiński,
• Krzysztof Woźniak and
• Konrad Kowalski

Beilstein J. Org. Chem. 2017, 13, 2521–2534, doi:10.3762/bjoc.13.249

• pyrenyl–thymine 2 was confirmed by single-crystal X-ray analysis. Crystal structure Crystals of 2 suitable for X-ray diffraction analysis were obtained by slow diffusion of pentane into a chloroform solution of 2. The oak ridge thermal-ellipsoid plot (ORTEP) with the atom labelling scheme is shown in

Nucleophilic and electrophilic cyclization of N-alkyne-substituted pyrrole derivatives: Synthesis of pyrrolopyrazinone, pyrrolotriazinone, and pyrrolooxazinone moieties

• Işıl Yenice,
• Sinan Basceken and
• Metin Balci

Beilstein J. Org. Chem. 2017, 13, 825–834, doi:10.3762/bjoc.13.83

• ) as expected. Finally, the structure of 12c was further confirmed by single-crystal X-ray analysis (Figure 5) [32]. The compound 13c could have the structure 16. However, in a structure like 16 one would expect a correlation between the methylene protons and the pyrrole ring carbon atoms. As we were

• single-crystal X-ray analysis (Figure 7) [32]. The following reaction mechanism was proposed for the formation of 19c (Scheme 6). The reaction starts with the π-activation of the triple bond by iodine to form the intermediate 20, which undergoes an intramolecular addition of the ester oxygen atom to the

From betaines to anionic N-heterocyclic carbenes. Borane, gold, rhodium, and nickel complexes starting from an imidazoliumphenolate and its carbene tautomer

• Ming Liu,
• Jan C. Namyslo,
• Martin Nieger,
• Mika Polamo and
• Andreas Schmidt

Beilstein J. Org. Chem. 2016, 12, 2673–2681, doi:10.3762/bjoc.12.264

• (crystallographic numbering, cf. Figure 2: C9) is clearly detectable at δ = 9.22 ppm in DMSO-d6, while the boron and fluorine atoms give resonance frequencies at δ = −3.45 ppm, and δ = −133.91, −159.97, −165.18 ppm in the 11B NMR and 19F NMR spectra, respectively. A single crystal X-ray analysis of the borane

• ), 6.72 ppm, and 5.81 ppm, respectively. Single crystals of [Rh(7)3] (11) were obtained by slow evaporation of a concentrated solution of 11 in a mixture of EtOAc and MeOH. The single crystal X-ray analysis proved that three anionic N-heterocyclic carbenes 7 serve as bidentate ligands, respectively

Bridgehead vicinal diallylation of norbornene derivatives and extension to propellane derivatives via ring-closing metathesis

• Sambasivarao Kotha and
• Rama Gunta

Beilstein J. Org. Chem. 2016, 12, 1877–1883, doi:10.3762/bjoc.12.177

• exo configuration. Thus, in the final compound 1a the newly formed 6-membered ring during RCM is supposed to be in the exo configuration. To our surprise, single-crystal X-ray analysis of 1a revealed that the 6-membered ring (C28–C30–C31–C32–C33–C27) formed via RCM is in endo configuration as depicted

Molecular weight control in organochromium olefin polymerization catalysis by hemilabile ligand–metal interactions

• Stefan Mark,
• Hubert Wadepohl and
• Markus Enders

Beilstein J. Org. Chem. 2016, 12, 1372–1379, doi:10.3762/bjoc.12.131

• 21% (3) to 81% (6). The ligand L3 as well as the pre-catalysts 4–8 were studied by single crystal X-ray analysis. A selection of molecular structures is presented in Figure 1 and details of the structure determination are presented in Table S1 (see Supporting Information File 1). Due to the rigid and

Copper-catalyzed [3 + 2] cycloaddition of (phenylethynyl)di-p-tolylstibane with organic azides

• Mizuki Yamada,
• Mio Matsumura,
• Yuki Uchida,
• Masatoshi Kawahata,
• Yuki Murata,
• Naoki Kakusawa,
• Kentaro Yamaguchi and
• Shuji Yasuike

Beilstein J. Org. Chem. 2016, 12, 1309–1313, doi:10.3762/bjoc.12.123

• yields. The CuAAC reaction of 1 with aryl azides such as 4-methylphenyl and 4-cyanophenyl azide gave a complex mixture, presumably due to the steric hindrance introduced by the aryl groups. The regiochemistry of 5-stibanotriazole 3a was elucidated by 1H NMR and confirmed by single-crystal X-ray analysis

Antibacterial structure–activity relationship studies of several tricyclic sulfur-containing flavonoids

• Lucian G. Bahrin,
• Henning Hopf,
• Peter G. Jones,
• Laura G. Sarbu,
• Cornelia Babii,
• Alina C. Mihai,
• Marius Stefan and
• Lucian M. Birsa

Beilstein J. Org. Chem. 2016, 12, 1065–1071, doi:10.3762/bjoc.12.100

• and 4f crystals suitable for single crystal X-ray analysis were obtained and the results are discussed in the X-ray analysis section. The acid-catalyzed cyclocondensation of flavanones 4a–m afforded the tricyclic flavonoids 5a–m in good yields [23] (Scheme 1). The formation of the 1,3-dithiolium ring

Scope and mechanism of the highly stereoselective metal-mediated domino aldol reactions of enolates with aldehydes

• M. Emin Cinar,
• Bernward Engelen,
• Martin Panthöfer,
• Hans-Jörg Deiseroth,
• Jens Schlirf and
• Michael Schmittel

Beilstein J. Org. Chem. 2016, 12, 813–824, doi:10.3762/bjoc.12.80

• transformations with five- (1g) and seven- (1i) membered rings failed most likely due to strain. The structure of product 7h, which precipitated from the crude mixture in crystalline form, was solved by single crystal X-ray analysis. The crystals are in the space group P21/c. It forms "fibers" with alternating

Synthesis and in vitro cytotoxicity of acetylated 3-fluoro, 4-fluoro and 3,4-difluoro analogs of D-glucosamine and D-galactosamine

• Štěpán Horník,
• Lucie Červenková Šťastná,
• Petra Cuřínová,
• Jan Sýkora,
• Kateřina Káňová,
• Roman Hrstka,
• Ivana Císařová,
• Martin Dračínský and
• Jindřich Karban

Beilstein J. Org. Chem. 2016, 12, 750–759, doi:10.3762/bjoc.12.75

• on reaction of 12 with DAST furnished orthoester 25 instead of the desired 4-fluoro derivative. The structure of orthoester 25 was confirmed by single crystal X-ray analysis. The formation of 25 resulted from an intramolecular displacement of the unstable alkoxysulfur intermediate 23 with the oxygen

• fluorohydrin 26 with DAST in benzene under heating afforded, as the main product, 3,4-difluoro-D-gluco analog 28 (46%), and the rearranged 2,6-anhydro compound 29 (12%) as a side product. Products 28 and 29 can be separated by careful chromatography and their structures were verified by single crystal X-ray

• analysis. Since fluorination of 12 with DAST failed to introduce fluorine at C-4β due to formation of orthoester 25, the reaction of 1,6:2,3-dianhydro-β-D-talopyranose 14 with DAST was utilized to give 1,6:2,3-dianhydro-4-deoxy-4-fluoro-β-D-talopyranose (30) with retention of the configuration at C-4 [39

Organocatalytic asymmetric Henry reaction of 1H-pyrrole-2,3-diones with bifunctional amine-thiourea catalysts bearing multiple hydrogen-bond donors

• Ming-Liang Zhang,
• Deng-Feng Yue,
• Zhen-Hua Wang,
• Yuan Luo,
• Xiao-Ying Xu,
• Xiao-Mei Zhang and
• Wei-Cheng Yuan

Beilstein J. Org. Chem. 2016, 12, 295–300, doi:10.3762/bjoc.12.31

• ). The absolute configuration of the major isomer 4i was unambiguously determined to be S by single-crystal X-ray analysis (Figure 1) [38]. The configurations of the other products were assigned by analogy. On the basis of our experimental results and the related reports about the bifunctional activation

• Supporting Information Supporting Information File 39: General procedure, analytical data and spectra of all compounds, methods for conversion. Supporting Information File 40: Single-crystal X-ray analysis of 4i. Acknowledgements We are grateful for financial support from the National Natural Science

Grubbs–Hoveyda type catalysts bearing a dicationic N-heterocyclic carbene for biphasic olefin metathesis reactions in ionic liquids

• Maximilian Koy,
• Hagen J. Altmann,
• Benjamin Autenrieth,
• Wolfgang Frey and
• Michael R. Buchmeiser

Beilstein J. Org. Chem. 2015, 11, 1632–1638, doi:10.3762/bjoc.11.178

• solvent (toluene) and the ionic liquid (IL) 1-butyl-2,3-dimethylimidazolium tetrafluoroborate [BDMIM+][BF4−]. The structure of Ru-2 was confirmed by single crystal X-ray analysis. Keywords: biphasic catalysis; ionic initiators; recycling; ROMP; ruthenium; Introduction Ionic metathesis catalysts offer

• gave the dicationic ruthenium alkylidene Ru-2 in 90% isolated yield (Scheme 1). This is to the best of our knowledge the first example of a ruthenium alkylidene bearing an NHC ligand with permanent dicationic charge. Crystals of Ru-2 suitable for single-crystal X-ray analysis were obtained from DMF

Towards inhibitors of glycosyltransferases: A novel approach to the synthesis of 3-acetamido-3-deoxy-D-psicofuranose derivatives

• Maroš Bella,
• Miroslav Koóš and
• Chun-Hung Lin

Beilstein J. Org. Chem. 2015, 11, 1547–1552, doi:10.3762/bjoc.11.170

• single-crystal X-ray analysis. However, removal of the pivaloyl group from derivative 10 afforded 3-acetamido-3-deoxy-1,2-O-isopropylidene-α-D-psicofuranose (12) which, after crystallization (EtOAc/hexane 1:2), afforded crystals suitable for X-ray analysis. This unambiguously confirmed the α