NHC-catalyzed cleavage of vicinal diketones and triketones followed by insertion of enones and ynones

• Ken Takaki,
• Makoto Hino,
• Akira Ohno,
• Kimihiro Komeyama,
• Hiroto Yoshida and
• Hiroshi Fukuoka

Beilstein J. Org. Chem. 2017, 13, 1816–1822, doi:10.3762/bjoc.13.176

• by NMR. Only the major isomer of 4ai crystallized from the mixture and thus Z-stereochemistry of the two aroyl groups (ClC6H4CO and PhCO) was confirmed by X-ray analysis (Figure 1) [20]. Electron-donating substituents of ynones 2 gave slightly better yields than electron-withdrawing ones. The yields

• confirmed by X-ray analysis as shown in Figure 2 [20]. Isolation of 10 prompted us to get the monoacylated Breslow intermediate C also as a stable compound. Treatment of benzil 1d with equimolar amounts of 3 and DIPEA at room temperature, followed by non-aqueous work-up and column chromatography gave

• crystalline product 12 in 92% yield (Scheme 6). Although 12 did not provide single crystals suitable for X-ray analysis, its structure was determined by NMR and elemental analysis. 1H NMR spectra of 12 showed eleven protons in the aromatic region, i.e., two ClC6H4, Me3C6H2, and one particular proton at δ 6.68

Bifunctional organocatalysts for the asymmetric synthesis of axially chiral benzamides

• Ryota Miyaji,
• Yuuki Wada,
• Akira Matsumoto,
• Keisuke Asano and
• Seijiro Matsubara

Beilstein J. Org. Chem. 2017, 13, 1518–1523, doi:10.3762/bjoc.13.151

• determined by X-ray analysis (see the Supporting Information File 1 for details), and the configurations of all other examples were assigned analogously. Once the optimal conditions for the transformation were established, we next proceeded to explore the substrate scope (Scheme 2). The substrate bearing a

A speedy route to sterically encumbered, benzene-fused derivatives of privileged, naturally occurring hexahydropyrrolo[1,2-b]isoquinoline

• Olga Bakulina,
• Alexander Ivanov,
• Vitalii Suslonov,
• Dmitry Dar’in and
• Mikhail Krasavin

Beilstein J. Org. Chem. 2017, 13, 1413–1424, doi:10.3762/bjoc.13.138

• -diastereoselectivity of the CCR is well documented in the literature [33] and is, therefore, unsurprising. However, the stereocontrol achieved in this reaction over 3 stereocenters present in 10l (obtained in 81% yield as a single diastereomer) is certainly quite noteworthy and was confirmed by X-ray analysis (Figure

• for syn-isomers. According to the X-ray analysis, the dihedral angle values in the C11H–C11aH fragment lie within the 165–170° and 55–58° range for anti- and syn-diastereomers, respectively (Supporting Information File 1, Table S1). Thus, for most of the 2H-indolenine-derived compounds (except for 10d

Construction of highly enantioenriched spirocyclopentaneoxindoles containing four consecutive stereocenters via thiourea-catalyzed asymmetric Michael–Henry cascade reactions

• Yonglei Du,
• Jian Li,
• Kerong Chen,
• Chenglin Wu,
• Yu Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2017, 13, 1342–1349, doi:10.3762/bjoc.13.131

• the catalyst d. The absolute configuration of 3g was determined by X-ray analysis (see Supporting Information File 1, Figure S1). Conclusion We have developed a highly efficient and practical strategy for a single step construction of saturated spirocyclopentaneoxindoles containing four consecutive

New tricks of well-known aminoazoles in isocyanide-based multicomponent reactions and antibacterial activity of the compounds synthesized

• Maryna V. Murlykina,
• Maryna N. Kornet,
• Sergey M. Desenko,
• Svetlana V. Shishkina,
• Oleg V. Shishkin,
• Aleksander A. Brazhko,
• Vladimir I. Musatov,
• Erik V. Van der Eycken and
• Valentin A. Chebanov

Beilstein J. Org. Chem. 2017, 13, 1050–1063, doi:10.3762/bjoc.13.104

• analysis (Figure 3). In the case of compounds 9 the presence of NOE between the signals of the methyl group and the CH group in the isoxazole moiety allowed to distinguish closely located signals of two CH groups (Figure 4). Ultimately, the structure of compounds 9 was proven by an X-ray analysis of

• correlations between the signals of NH protons and corresponding carbon atoms (through two and three bonds, Figure 2) allowed final distinguishing the shifts of three NH groups signals in 1H NMR spectra. However, the final assignment of the structure A for heterocycles 4 was made with the help of X-ray

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

Dimerization reactions of aryl selenophen-2-yl-substituted thiocarbonyl S-methanides as diradical processes: a computational study

• Michael L. McKee,
• Grzegorz Mlostoń,
• Katarzyna Urbaniak and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2017, 13, 410–416, doi:10.3762/bjoc.13.44

• , substituents located in 4-position of the phenyl ring influence the yield of 9 formed in a competitive reaction with the formal [2 + 3]-cycloaddition of 8 with the starting thioketone 10 leading to the sterically crowded 1,3-dithiolane 11. The structure of the dimer 9, confirmed by an X-ray analysis [13

The synthesis of α-aryl-α-aminophosphonates and α-aryl-α-aminophosphine oxides by the microwave-assisted Pudovik reaction

• Erika Bálint,
• Ádám Tajti,
• Anna Ádám,
• István Csontos,
• Konstantin Karaghiosoff,
• Mátyás Czugler,
• Péter Ábrányi-Balogh and
• György Keglevich

Beilstein J. Org. Chem. 2017, 13, 76–86, doi:10.3762/bjoc.13.10

• isolated and characterized. Except six compounds, these were new compounds. Furthermore, the reactivity was mapped, and the mechanism was evaluated by B3LYP/6-31G (d,p) calculations. The crystal structure of two α-aminophosphonates was studied by X-ray analysis suggesting centrosymmetric dimers. IR spectra

Diastereoselective anodic hetero- and homo-coupling of menthol-, 8-methylmenthol- and 8-phenylmenthol-2-alkylmalonates

• Matthias C. Letzel,
• Hans J. Schäfer and
• Roland Fröhlich

Beilstein J. Org. Chem. 2017, 13, 33–42, doi:10.3762/bjoc.13.5

• diastereomers of 23–25 were obtained from crystal structure analyses and the correlation of the 13C NMR data. According to an X-ray analysis the minor diastereomer 23b has the configuration (S) at the new formed stereogenic center (Figure 2) [23]. The configuration of the new stereogenic centers in compounds 24

• diastereomers 28a and 29a was determined by X-ray analysis (Figure 4 [23] and Figure 5 [23], hydrogen atoms are left out, except those formed at the new stereogenic centers). The new stereogenic centers in both cases have (2’R,3’R)-configuration. For the diastereomers 26b, 27b, 28b and 29b a set of 1H and 13C

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

• ) chloride at reflux temperature resulted in the formation of the nickel complex [Ni(7)2] (12, Scheme 2). Single crystals were obtained by slow evaporation of 12 from EtOAc/MeOH. The X-ray analysis shows two independent nickel complexes which are connected via hydrogen bonds to two water molecules (Figure 5

Thiazol-4-one derivatives from the reaction of monosubstituted thioureas with maleimides: structures and factors determining the selectivity and tautomeric equilibrium in solution

• Alena S. Pankova,
• Pavel R. Golubev,
• Alexander F. Khlebnikov,
• Alexander Yu. Ivanov and
• Mikhail A. Kuznetsov

Beilstein J. Org. Chem. 2016, 12, 2563–2569, doi:10.3762/bjoc.12.251

• nitrogen atom at δ ≈ 235 ppm, which is obviously the C=N atom of this form. No correlations were found for the proton signal at δ 11.68 ppm of 3b-I as mentioned for 3a-I. However, X-ray analysis indicated this proton in the crystal structure of 3b (Figure 1) [27] and there are two partially occupied

• Supporting Information File 324: Experimental procedures, characterization data and copies of the 1H, 13C and 2D NMR spectra; X-ray analysis data for thiazolidine 3b. Acknowledgements The work was supported by a grant of the President of Russian Federation (no. MK-5965.2016.3). NMR, HRMS, and XRD analyses

Sydnone C-4 heteroarylation with an indolizine ring via Chichibabin indolizine synthesis

• Florin Albota,
• Mino R. Caira,
• Constantin Draghici,
• Florea Dumitrascu and
• Denisa E. Dumitrescu

Beilstein J. Org. Chem. 2016, 12, 2503–2510, doi:10.3762/bjoc.12.245

• latter compounds were also transformed to sydnone-indolizines connected through a keto group at the C-4 position by refluxing them in 1,2-epoxybutane with an activated alkyne. The structures of the new compounds were assigned by FTIR, NMR spectroscopy and X-ray analysis. Keywords: biheteroaryl

Radical polymerization by a supramolecular catalyst: cyclodextrin with a RAFT reagent

• Kohei Koyanagi,
• Yoshinori Takashima,
• Takashi Nakamura,
• Hiroyasu Yamaguchi and
• Akira Harada

Beilstein J. Org. Chem. 2016, 12, 2495–2502, doi:10.3762/bjoc.12.244

• transfer agent (CTA) that has α-cyclodextrin (α-CD) as a host molecule (α-CD-CTA). Prior to the polymerization of N,N-dimethylacrylamide (DMA), we investigated the complex formation of α-CD with DMA. Single X-ray analysis demonstrated that α-CD includes DMA inside its cavity. When DMA was polymerized in

Construction of bis-, tris- and tetrahydrazones by addition of azoalkenes to amines and ammonia

• Artem N. Semakin,
• Aleksandr O. Kokuev,
• Yulia V. Nelyubina,
• Alexey Yu. Sukhorukov,
• Petr A. Zhmurov,
• Sema L. Ioffe and
• Vladimir A. Tartakovsky

Beilstein J. Org. Chem. 2016, 12, 2471–2477, doi:10.3762/bjoc.12.241

• ]. Tetraazaadamantane with this substitution pattern is a promising platform for the design of supramolecular recognizing systems and for the construction of new molecular cage architectures. The formation of the 1,4,6,10-tetraazaadamantane cage was unambiguously confirmed by X-ray analysis of the crystal solvate of

Combined experimental and theoretical studies of regio- and stereoselectivity in reactions of β-isoxazolyl- and β-imidazolyl enamines with nitrile oxides

• Ilya V. Efimov,
• Marsel Z. Shafikov,
• Nikolai A. Beliaev,
• Natalia N. Volkova,
• Tetyana V. Beryozkina,
• Wim Dehaen,
• Zhijin Fan,
• Viktoria V. Grishko,
• Gert Lubec,
• Pavel A. Slepukhin and
• Vasiliy A. Bakulev

Beilstein J. Org. Chem. 2016, 12, 2390–2401, doi:10.3762/bjoc.12.233

• aromatic 4-imidazolylisoxazoles 4b,d,e–g. Probably isoxazolines 3a–c are more stable than other compounds of type 3 under column purification conditions. The 3,4-disubstituted isoxazole structures of compounds 4a–p were confirmed by the combination of mass spectrometry, NMR spectroscopy, and X-ray analysis

High performance p-type molecular electron donors for OPV applications via alkylthiophene catenation chromophore extension

• Paul B. Geraghty,
• Calvin Lee,
• Jegadesan Subbiah,
• Wallace W. H. Wong,
• James L. Banal,
• Mohammed A. Jameel,
• Trevor A. Smith and
• David J. Jones

Beilstein J. Org. Chem. 2016, 12, 2298–2314, doi:10.3762/bjoc.12.223

• as-cast film emission. Detailed variable temperature X-ray analysis of BQR thin films is currently underway to better understand these changes. CV and PESA: The electrochemical properties of the BXR series of materials have been examined by cyclic voltammetry (CV), photoelectron spectroscopy in air

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

A T-shape diphosphinoborane palladium(0) complex

• Patrick Steinhoff and
• Michael E. Tauchert

Beilstein J. Org. Chem. 2016, 12, 1573–1576, doi:10.3762/bjoc.12.152

• (CyDPBPh)Pd(0) 9, which was characterized by X-ray analysis. Keywords: ambiphilic ligand; coordination chemistry; diphosphinoborane; organometallics; palladium; Introduction The amplification of traditional bidentate chelating L2-type ligands with a tethered borane functionality (e.g., Bourissou’s

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

• new broad absorption band at around 1040 cm−1 is attributed to the tetrafluoroborate anion. ESIMS confirms the structure of the positive molecular fragment of each tricyclic flavonoid ([M − BF4]+). Single crystals suitable for X-ray analysis were obtained for 5a and 5b and the results are presented in

Cationic Pd(II)-catalyzed C–H activation/cross-coupling reactions at room temperature: synthetic and mechanistic studies

• Takashi Nishikata,
• Alexander R. Abela,
• Shenlin Huang and
• Bruce H. Lipshutz

Beilstein J. Org. Chem. 2016, 12, 1040–1064, doi:10.3762/bjoc.12.99

• intermediate, characterized by X-ray analysis. Roles of various additives in the stepwise process have also been studied. Keywords: arylation; cationic palladium; C–H functionalization; green chemistry; olefination; Introduction Transition metal-catalyzed, direct functionalization of aryl C–H bonds has made

• ][18][19][20][21][22], e.g., HBF4 was found to be critical for generation of biaryl 3h in good yield. The structure of the ortho-arylated product was confirmed by X-ray analysis. While similar reactions, in addition to requiring high temperatures, have typically employed strong acids such as TFA as the

• acetonitrile, as confirmed by NMR. The facile formation of this species supports the intermediacy of a palladacycle in the catalytic cycle. The structure of the isolated palladacycle was confirmed by X-ray analysis [216]. An ORTEP plot for palladacycle 6 is shown in Figure 7. The molecular structure consists

Reactions of N,3-diarylpropiolamides with arenes under superelectrophilic activation: synthesis of 4,4-diaryl-3,4-dihydroquinolin-2(1H)-ones and their derivatives

• Larisa Yu. Gurskaya,
• Diana S. Belyanskaya,
• Dmitry S. Ryabukhin,
• Denis I. Nilov,
• Irina A. Boyarskaya and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2016, 12, 950–956, doi:10.3762/bjoc.12.93

• , and 4a,b were determined by means of 1H, 13C, 19F NMR, HRMS methods (see Supporting Information File 1), and X-ray analysis in case of compound 2f (Figure 1). We found that the best conditions for the synthesis of dihydroquinolines 2 from amides 1 and arenes were as follows: TfOH, room temperature

A modular approach to neutral P,N-ligands: synthesis and coordination chemistry

• Vladislav Vasilenko,
• Torsten Roth,
• Clemens K. Blasius,
• Sebastian N. Intorp,
• Hubert Wadepohl and
• Lutz H. Gade

Beilstein J. Org. Chem. 2016, 12, 846–853, doi:10.3762/bjoc.12.83

• [2a-Rh(cod)]BF4, [2b-Rh(cod)]BF4, of the corresponding iridium complexes and of complexes [5-Rh(cod)]BF4, [5-Ir(cod)]OTf and [7-Rh(cod)]BF4 suitable for X-ray analysis by layering solutions of the complexes in dichloromethane with toluene and pentane. Instructive examples of the structural properties

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

• achieved by using chiral column chromatography (Chiralpak AD, Daicel) followed by recrystallization from H2O/MeOH (1:4) providing the appropriate crystal for X-ray analysis. Accordingly, the enantiopure crystal of 5a was unambiguously assigned to a tetrahydro-2H-pyran-2,4-diol structure with all phenyl and

• 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