Silyl-protective groups influencing the reactivity and selectivity in glycosylations

• Mikael Bols and
• Christian Marcus Pedersen

Beilstein J. Org. Chem. 2017, 13, 93–105, doi:10.3762/bjoc.13.12

• the NMR spectrum of this compound displayed line broadening indicating some conformational inversion, but the X-ray structure of the crystalline compound was in the conventional 1C4 conformation. Yet the compound was clearly very reactive as it selectively could glycosylate the 2-OH of thioglycoside

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

• diastereoselectivity ranging from 5 to 65% de. Electrolyses without a coacid led to diastereomeric homo-coupling products in 21–50% yield with ratios of diastereomers being 1.17:2.00:0.81 to 7.03:2.00. The stereochemistry of the new stereogenic centers was confirmed by X-ray structure analysis and 13C NMR data

Supramolecular frameworks based on [60]fullerene hexakisadducts

• Andreas Kraft,
• Johannes Stangl,
• Ana-Maria Krause,
• Klaus Müller-Buschbaum and
• Florian Beuerle

Beilstein J. Org. Chem. 2017, 13, 1–9, doi:10.3762/bjoc.13.1

• electron microscopy were carried out on activated and non-activated samples of HFF-3. They corroborate the strong anisotropic character of crystalline needles of the X-ray structure determination and do not show changes upon activation (see Figure S13 in Supporting in Information File 1). However, powder X

Organofluorine chemistry: Difluoromethylene motifs spaced 1,3 to each other imparts facial polarity to a cyclohexane ring

• Mathew J. Jones,
• Ricardo Callejo,
• Alexandra M. Z. Slawin,
• Michael Bühl and
• David O'Hagan

Beilstein J. Org. Chem. 2016, 12, 2823–2827, doi:10.3762/bjoc.12.281

• offer new possibilities for the design of performance molecules extending from organic materials research to medicinal chemistry. Selected fluorinated polar alicyclic scaffolds. X-ray structure of compound 4c. The image shows two molecules stacked with the non-fluorine face pointing to an adjacent

Characterization of the synthetic cannabinoid MDMB-CHMCZCA

• Carina Weber,
• Stefan Pusch,
• Dieter Schollmeyer,
• Sascha Münster-Müller,
• Michael Pütz and
• Till Opatz

Beilstein J. Org. Chem. 2016, 12, 2808–2815, doi:10.3762/bjoc.12.279

• was possible by comparison of the experimental and DFT-calculated VCD spectra (Figure 5) with a satisfactory ESI value of 80%. Eventually, the absolute configuration of (S)-3 could be unambiguously determined by X-ray structure analysis of a single crystal, which was obtained by slow cooling of a hot

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

• of the carbene atom appears at δ = 183.9 ppm. Single crystals of the gold complex 9 were obtained by slow evaporation of a concentrated solution of 9 in MeOH and a molecular drawing is shown in Figure 3. The X-ray structure revealed a mixed occupation of the same position with chloride and bromide

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

• formation of sydnone-indolizines 12. Supporting Information Experimental details of synthetic procedures and experimental details of X-ray structure analyses. Crystallographic information files (CIF) for compound 9d and 12c, listing crystal data, experimental and refinement details, and molecular

Synthesis, dynamic NMR characterization and XRD studies of novel N,N’-substituted piperazines for bioorthogonal labeling

• Constantin Mamat,
• Marc Pretze,
• Matthew Gott and
• Martin Köckerling

Beilstein J. Org. Chem. 2016, 12, 2478–2489, doi:10.3762/bjoc.12.242

• showed a Tc of 248 K with a ΔG# of 11.1 kJ/mol [23] whereas piperidine shows a higher ΔG# of 42.3 and N-methylpiperidine a ΔG# = 49.8 kJ/mol [21][28]. X-ray structure analyses of 3a and 4b Single crystals of 3a and 4b were obtained and their molecular structures determined using single crystal X-ray

• from coalescence temperatures Tc which were determined from dynamic 1H NMR measurements. The formation of conformers resulting from the partial double bond was additionally determined and verified using single crystal X-ray structure analysis. The second coalescence point is caused by the reduced

• structure analysis. Crystals of 3a have monoclinic symmetry of the space group C2/c. Crystals of 4b have monoclinic symmetry of the space group P21/n. The C14–C15 distance of 1.188(1) Å and the C13–C14–C15 angle of 178.2(1)° clearly indicate this group to be an alkyne residue, thus enabling the use of the

A direct method for the N-tetraalkylation of azamacrocycles

• Andrew J. Counsell,
• Angus T. Jones,
• Matthew H. Todd and
• Peter J. Rutledge

Beilstein J. Org. Chem. 2016, 12, 2457–2461, doi:10.3762/bjoc.12.239

• via recrystallization or by passing the product through a short silica plug (see Table 1 and Supporting Information File 1 for details). Recrystallisation of 3 from a methanolic solution containing KClO4 yielded large, colourless, crystalline prisms. Single crystal X-ray structure determination

Stereoselective synthesis of fused tetrahydroquinazolines through one-pot double [3 + 2] dipolar cycloadditions followed by [5 + 1] annulation

• Xiaofeng Zhang,
• Kenny Pham,
• Shuai Liu,
• Marc Legris,
• Alex Muthengi,
• Jerry P. Jasinski and
• Wei Zhang

Beilstein J. Org. Chem. 2016, 12, 2204–2210, doi:10.3762/bjoc.12.211

• product 7 under the optimized reaction conditions, see Table 1, entry 5. nd = not detected. X-ray structure of 7h. [5 + 1] Annulation for tetrahydroquinazolines 1. Polycyclic scaffolds derived from [3 + 2] adducts 2. Proposed mechanism for the 2nd [3 + 2] cycloaddition and denitrogenation. One-pot double

New furoisocoumarins and isocoumarins from the mangrove endophytic fungus Aspergillus sp. 085242

• Ze’en Xiao,
• Senhua Chen,
• Runlin Cai,
• Shao’e Lin,
• Kui Hong and
• Zhigang She

Beilstein J. Org. Chem. 2016, 12, 2077–2085, doi:10.3762/bjoc.12.196

• configuration of compound 2 was unambiguously determined by X-ray structure analysis and ECD calculation. Moreover, the absolute configurations of compounds 3–5 were assigned by comparison of their ECD spectra with isocoumarins described in the literature. Asperisocoumarins C and D (3 and 4) were fully

Rapid regio- and multi-coupling reactivity of 2,3-dibromobenzofurans with atom-economic triarylbismuths under palladium catalysis

• Maddali L. N. Rao,
• Jalindar B. Talode and
• Venneti N. Murty

Beilstein J. Org. Chem. 2016, 12, 2065–2076, doi:10.3762/bjoc.12.195

• minor amounts. Evidently, this generalization of bis-coupling reactivity was proved to be operationally simple with high reactivity and yields involving 2 h short reaction time and with sub-stoichiometric loadings of the bismuth reagent. Incidentally, we could also obtain the X-ray structure analysis

• expected to attract easy applications in structural elaborations of medicinally important benzofuran scaffolds. Important benzofuran skeletons. X-ray structure of bis-coupling product 3.1 (CCDC-1425338) [43]. Bis- and tris-couplings. Screening for mono-arylation.a Cross-couplings of 2,3-dibromobenzofurans

Scope and limitations of a DMF bio-alternative within Sonogashira cross-coupling and Cacchi-type annulation

• Kirsty L. Wilson,
• Alan R. Kennedy,
• Jane Murray,
• Ben Greatrex,
• Craig Jamieson and
• Allan J. B. Watson

Beilstein J. Org. Chem. 2016, 12, 2005–2011, doi:10.3762/bjoc.12.187

• Cyrene as a solvent, providing guidance emerging in relation to the thermal and chemical (base) stabilities of this promising green solvent. Cyrene vs. DMF – selected physical properties [31][32]. Aldol products 4a and 4b and single crystal X-ray structure of 4b. The Sonogashira reaction. Cyrene-based

Potent triazine-based dehydrocondensing reagents substituted by an amido group

• Munetaka Kunishima,
• Daiki Kato,
• Nobu Kimura,
• Masanori Kitamura,
• Kohei Yamada and
• Kazuhito Hioki

Beilstein J. Org. Chem. 2016, 12, 1897–1903, doi:10.3762/bjoc.12.179

• intermediate 7 (Scheme 2). Single-crystal X-ray structure analysis, two-dimensional NMR spectroscopy, or derivatization of I–VI was performed to unambiguously determine their structures, i.e., whether the N- or O-substituted derivative was prepared from the amido anion (Supporting Information File 1). To

• esterification of 3-phenylpropanoic acid (1a) in neat MeOH were studied (Figure 3). Although X was shown to exist as a dihydrate by elemental analysis and single-crystal X-ray structure analysis, the yield of methyl 3-phenylpropanoate was quantitative. The rate of esterification with X was faster than that with

Experimental and theoretical investigations on the high-electron donor character of pyrido-annelated N-heterocyclic carbenes

• Michael Nonnenmacher,
• Dominik M. Buck and
• Doris Kunz

Beilstein J. Org. Chem. 2016, 12, 1884–1896, doi:10.3762/bjoc.12.178

• heptafulvalene) as well as the very low N–C–N angle by X-ray structure analysis [41]. Weiss proposed this carbene to have a “built-in umpolung” [39] ability which means that there could be a participation of the dicationic bisylidene resonance form as it is usually described for carbodiphosphoranes [49] and

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

• compound 2a was formed from the corresponding O-allyl compound via CR. Based on the X-ray structure of 1a and the above observations, it is clear that the allyl groups in 2a are in endo configuration which can be explained as follows. Since the stereocenters are unaffected during the RCM sequence it is

• evident that the allyl groups present in 2a should be in endo configuration. To confirm the configuration of the allyl groups, the X-ray structure of previously reported oxa-bowl/propellane hybrid (15) [38] was also recorded and it is in agreement with the above findings (Figure 3). These results

Catalytic Chan–Lam coupling using a ‘tube-in-tube’ reactor to deliver molecular oxygen as an oxidant

• Carl J. Mallia,
• Paul M. Burton,
• Alexander M. R. Smith,
• Gary C. Walter and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2016, 12, 1598–1607, doi:10.3762/bjoc.12.156

• has enabled this work to be undertaken. Furthermore, we are grateful to Dr A. Batsanov (Durham University, Department of Chemistry) for solving the X-ray structure.

Dinuclear thiazolylidene copper complex as highly active catalyst for azid–alkyne cycloadditions

• Anne L. Schöffler,
• Ata Makarem,
• Frank Rominger and
• Bernd F. Straub

Beilstein J. Org. Chem. 2016, 12, 1566–1572, doi:10.3762/bjoc.12.151

• vacuo to give the colourless product 1b (1.50 g, 2.75 mmol, 76%). Single crystals of salt 1b that were suitable for an X-ray structure analysis were obtained from acetone/diethyl ether. 1H NMR (400.33 MHz, acetone-d6, 295.0 K) δ 9.88 (s, 2H, NCHS), 5.42 (s, 4H, CH2), 2.68 (s, 6H, NCCH3), 2.66 (s, 6H

• (100.0) [M − 2Cu – Oac − PF6 + CH3O]+, 397.0392 (17.7), 599.0698 (69.9); calculated for [M − 2Cu – Oac − PF6 + CH3O]+: 283.0949, found: 283.0935. IR (ATR) ν = 1594 (w), 1555 (m), 1447 (m), 1397 (w), 1328 (w), 835 (s), 691 (m) cm−1; mp 175 °C dec. Ball-and-stick model [42][43] of a single crystal X-ray

• structure of hexafluorophosphate salt 1b (CCDC 1472789). Color code: black carbon, grey hydrogen, yellow sulfur, blue nitrogen, magenta phosphorus, green fluorine. Time-conversion-diagram of the CuAAC reaction of benzyl azide with either phenylacetylene or ethyl propiolate in the presence of copper complex

Flow carbonylation of sterically hindered ortho-substituted iodoarenes

• Carl J. Mallia,
• Gary C. Walter and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2016, 12, 1503–1511, doi:10.3762/bjoc.12.147

• -substituent directly over an axial site (Figure 1). The ortho-substituent therefore acts as a steric buttress hindering the approach of the incoming carbon monoxide thus slowing down the rate of the reaction. An X-ray structure of trans-bromo(o-tolyl)bis(triphenylphosphine)palladium(II) complex was reported

• that the sterics at the 5-position are not affecting the yield with a large group at the 5-position of substrate 30 [42] (see X-ray structure of substrate 33, Figure 5) actually leading to a better yield than obtained for product 27 which contains the smaller ethoxy group at the 5-position. The lowest

• of X-ray structure; C) ball and stick representation of X-ray structure showing the tolyl group only; D) topside view of X-ray structure [18]. Reverse “tube-in-tube” reactor. Phosphine ligands used for the ortho-carbonylation reaction. X-ray structure of substrate 33. Comparison of plug flow reactor

Modular synthesis of the pyrimidine core of the manzacidins by divergent Tsuji–Trost coupling

• Sebastian Bretzke,
• Stephan Scheeff,
• Felicitas Vollmeyer,
• Friederike Eberhagen,
• Frank Rominger and
• Dirk Menche

Beilstein J. Org. Chem. 2016, 12, 1111–1121, doi:10.3762/bjoc.12.107

• an X-ray structure of tert-butylsulfinylamine 28 was obtained. Remarkably, these types of substances have not been broadly evaluated by X-ray structural analysis which adds to the importance of this general evaluation. Next, we focused on further homologation towards a suitably functionalized urea

• . Modular concept for manzacidin synthesis based on a Tsuji–Trost coupling of joint intermediate 5. X-ray structure of 39. General concept for heterocycles synthesis based on a nucleophilic addition and Tsuji–Trost coupling. Synthesis of homoallylic alcohol 12 by multi-component reactions. Preparation of

Towards the total synthesis of keramaphidin B

• Pavol Jakubec,
• Alistair J. M. Farley and
• Darren J. Dixon

Beilstein J. Org. Chem. 2016, 12, 1096–1100, doi:10.3762/bjoc.12.104

• single X-ray crystal diffraction data of 14. Acknowledgements This work was supported by the EPSRC (Leadership Fellowship to D.J.D., Post-Doctoral Fellowship to P.J. and Doctoral Training Grant [EP/M50659X/1] to A.J.M.F.). We also thank Matt Rattley, Jinchao Yang for X-ray structure determination and

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

• , 2.0 equiv). a2 wt % Brij 35 in water instead of EtOAc. Representative results in EtOAc. Conducted at rt in EtOAc with 10 mol % Pd(OAc)2, HBF4 (1 equiv), arylurea (1, 0.25 mmol), BQ (3 equiv) and acrylate (2, 2.0 equiv). X-ray structure of palladacycle 6 with thermal ellipsoids at the 50% probability

Synthesis of 2,1-benzisoxazole-3(1H)-ones by base-mediated photochemical N–O bond-forming cyclization of 2-azidobenzoic acids

• Daria Yu. Dzhons and
• Andrei V. Budruev

Beilstein J. Org. Chem. 2016, 12, 874–881, doi:10.3762/bjoc.12.86

• : 37717). In addition, the structure was confirmed by the alternative synthesis of 2a through the heterocyclization of 2-nitrobenzoic acid [28][29] and X-ray structure analysis [33]. The authors observed that the yields of both 2a and 3a increased with increasing amount of water as nucleophilic solvent in

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

• irreversible formation of the aldol condensation product 6ac, which is obtained in 73% yield in presence of AlCl3, on expense of 5a. The X-ray structure of racemic 5a (from ethanol) could not be solved due to the presence of a solid racemate in the orthorhombic space group P212121 (no. 19). Three axial hydroxy

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

• currently underway. The X-ray structure of compound 4i. A proposed transition state for the asymmetric Henry reaction. The strategy to construct chiral 3-substituted-3-hydroxy-1H-pyrrol-2(3H)-ones. Screening of the catalysts and solvents.a Further optimization of conditions.a Scope of the reaction.a