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

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

A quadruple cascade protocol for the one-pot synthesis of fully-substituted hexahydroisoindolinones from simple substrates

• Hong-Bo Zhang,
• Yong-Chun Luo,
• Xiu-Qin Hu,
• Yong-Min Liang and
• Peng-Fei Xu

Beilstein J. Org. Chem. 2016, 12, 253–259, doi:10.3762/bjoc.12.27

• 15:1 diastereoselectivity, respectively (Table 2, entries 14 and 15). When substrates with different R2 and R3 were used in this reaction, the corresponding products were obtained in medium yield and diastereoselectivity (Table 2, entries 16–20). The structure of 3p was determined by X-ray analysis

• for all new compounds and X-ray analysis of compound 3. Acknowledgements We are grateful to the NSFC (21172097, 21202070, 21302075 and 21372105), the International S&T Cooperation Program of China (2013DFR70580), the National Natural Science Foundation from Gansu Province of China (no. 1204WCGA015

Interactions of cyclodextrins and their derivatives with toxic organophosphorus compounds

• Sophie Letort,
• Sébastien Balieu,
• William Erb,
• Géraldine Gouhier and
• François Estour

Beilstein J. Org. Chem. 2016, 12, 204–228, doi:10.3762/bjoc.12.23

• phosphate moiety against external nucleophiles attack by impairing the entry of hydroxide ions. X-ray analysis of fenitrothion-TRIMEB and -DIMEB complexes showed that the phosphorothioate groups are close to the primary alcohols of the CDs. As a result of intramolecular hydrogen bonds O-2···HO-3’, the

A journey in bioinspired supramolecular chemistry: from molecular tweezers to small molecules that target myotonic dystrophy

• Steven C. Zimmerman

Beilstein J. Org. Chem. 2016, 12, 125–138, doi:10.3762/bjoc.12.14

• cleft was not only a significant synthetic challenge, I questioned whether the group might not distort the spacer, thereby altering its dimensions. I was able to prepare small quantities (<100 mg) of 6 and 7 and crystallize both for X-ray analysis (Figure 4) [16]. The solid state structure of 6 revealed

New metathesis catalyst bearing chromanyl moieties at the N-heterocyclic carbene ligand

• Agnieszka Hryniewicka,
• Szymon Suchodolski,
• Agnieszka Wojtkielewicz,
• Jacek W. Morzycki and
• Stanisław Witkowski

Beilstein J. Org. Chem. 2015, 11, 2795–2804, doi:10.3762/bjoc.11.300

• solid state at 0 °C for a few weeks (NMR test). Attempts to obtain a monocrystal that would be suitable for X-ray analysis failed. The 1H NMR spectrum confirmed the structure of the catalyst. In the 13C NMR spectrum, some signals were broad and weak, e.g., signals of the quaternary aromatic carbon atoms

Organocatalytic and enantioselective Michael reaction between α-nitroesters and nitroalkenes. Syn/anti-selectivity control using catalysts with the same absolute backbone chirality

• Jose I. Martínez,
• Uxue Uria,
• Maria Muñiz,
• Efraím Reyes,
• Luisa Carrillo and
• Jose L. Vicario

Beilstein J. Org. Chem. 2015, 11, 2577–2583, doi:10.3762/bjoc.11.277

• nitroalkenes were not suitable substrates for the reaction, probably due to their tendency to polymerize under the reaction conditions. The absolute configuration was determined by X-ray analysis of products anti-3a and syn-3o for which suitable crystals could be obtained (Figure 1). The crystallographic

2-Hetaryl-1,3-tropolones based on five-membered nitrogen heterocycles: synthesis, structure and properties

• Yury A. Sayapin,
• Inna O. Tupaeva,
• Alexandra A. Kolodina,
• Eugeny A. Gusakov,
• Vitaly N. Komissarov,
• Igor V. Dorogan,
• Nadezhda I. Makarova,
• Anatoly V. Metelitsa,
• Valery V. Tkachev,
• Sergey M. Aldoshin and
• Vladimir I. Minkin

Beilstein J. Org. Chem. 2015, 11, 2179–2188, doi:10.3762/bjoc.11.236

• diffraction. 2-(2-Benzoxa(thia)zolyl)-6-alkoxycarbonylphenols display intense green fluorescence with anomalous Stokes shifts caused by the excited state intramolecular proton transfer (ESIPT) effects. Keywords: β-tropolones; fluorescence; intramolecular hydrogen bond; tautomerism; X-ray analysis

• . Unfortunately, we were unable to obtain crystals of 2-(benzoxazol-2-yl)-1,3-tropolones suitable for X-ray analysis. In the independent parts of the elementary unit cells of 5g and 6e two molecules are located slightly differing in their structural details (Figures S1 and S2 in Supporting Information File 1

Photoinduced 1,2,3,4-tetrahydropyridine ring conversions

• Baiba Turovska,
• Henning Lund,
• Viesturs Lūsis,
• Anna Lielpētere,
• Edvards Liepiņš,
• Sergejs Beljakovs,
• Inguna Goba and
• Jānis Stradiņš

Beilstein J. Org. Chem. 2015, 11, 2166–2170, doi:10.3762/bjoc.11.234

• mmol) [17][18] in chloroform (25 mL). Crystals suitable for X-ray analysis were obtained after evaporation of the chloroform by a stream of dioxygen; elemental analysis, 1H, 13C NMR spectra and X-ray analysis confirmed the structure of hydroperoxide 2 (Figure 2) as the only product of the reaction