Self-assembled coordination thioether silver(I) macrocyclic complexes for homogeneous catalysis

• Zhen Cao,
• Aline Lacoudre,
• Cybille Rossy and
• Brigitte Bibal

Beilstein J. Org. Chem. 2019, 15, 2465–2472, doi:10.3762/bjoc.15.239

• analysis of monocrystals revealed the syn-conformation of 1 (Scheme 1). A variable temperature 1H NMR (VT-NMR, Figures S10–12 in Supporting Information File 1) experiment conducted on syn-1 in the range of –30 to 110 °C in C2D2Cl4 showed the broadening of proton signals, due to the restricted rotation of

• originate from the presence of several species in solution, such as self-aggregates, mixture of conformers, mixture of diastereoisomers or complexes with different stoichiometry. To investigate the possible self-aggregation of complexes 1a–c (7 mM), VT NMR experiments were conducted between –30 °C and 60 °C

• anthracene core (H4). Similar changes on VT NMR were observed for complex 1b and 1c (see Supporting Information File 1, Figures S11 and 12), with chemical shift variations in the range of 0.1 to 0.3 ppm for 1c. The little differences observed on 1H NMR spectra at 60 °C accounted for a slight change in the

Bi-mediated allylation of aldehydes in [bmim][Br]: a mechanistic investigation

• Mrunesh Koli,
• Sucheta Chatterjee,
• Subrata Chattopadhyay and
• Dibakar Goswami

Beilstein J. Org. Chem. 2018, 14, 2198–2203, doi:10.3762/bjoc.14.193

• stoichiometric/near-stoichiometric amounts of reagents. Plausibly, [bmim][Br] activates Bi metal by a charge transfer mechanism. The 1H VT-NMR studies suggested that both the allylating species, allylbismuth dibromide and diallylbismuth bromide, are generated in situ. Keywords: allylation; bismuth; [bmim][Br

• an RTIL. The generality of the protocol was established by subjecting a variety of aldehydes to allylation. Moreover, we have probed the active allylbismuth species generated in situ using 1H VT-NMR, and have proposed a plausible mechanism for its formation. Partial 1H NMR spectra (recorded at two

Calix[6]arene-based atropoisomeric pseudo[2]rotaxanes

• Carmine Gaeta,
• Carmen Talotta and
• Placido Neri

Beilstein J. Org. Chem. 2018, 14, 2112–2124, doi:10.3762/bjoc.14.186

• formation of the two atropoisomeric pseudo[2]rotaxanes 3+1cone and 3+11,2,3-alt. Synthesis of threads 2+ and 3+. Reagents and conditions: a) hexamethyldisilazane, LiClO4, 30 min, 60 °C; b) CH3OH, NaBH4, 2 h, 25 °C; c) TFPBNa, dry MeOH, 25 °C, 18 h. Supporting Information Supporting Information File 408: VT

• NMR studies of hexyloxycalix[6]arene 1, 2D COSY and HSQC spectra of atropoisomeric pseudorotaxanes, details of DFT calculations and atomic coordinates. Acknowledgements The authors acknowledge the Regione Campania (POR CAMPANIA FESR 2007/2013 O.O.2.1, CUP B46D14002660009) for the FT-ICR mass

Design, synthesis and structure of novel G-2 melamine-based dendrimers incorporating 4-(n-octyloxy)aniline as a peripheral unit

• Cristina Morar,
• Pedro Lameiras,
• Attila Bende,
• Gabriel Katona,
• Emese Gál and
• Mircea Darabantu

Beilstein J. Org. Chem. 2018, 14, 1704–1722, doi:10.3762/bjoc.14.145

• macromolecular shape in solution). DFT calculations (in solution), (VT) NMR and IR (KBr) spectroscopy supported these assignments. TEM analysis revealed the ability of the title compounds towards self-assembling into homogeneously packed spherical nano-aggregates. Conclusions: The (non)covalent synthesis and

• quantitative yields (Scheme 4) (Supporting Information File 1, pp. S6–S11; pp. S24–S39, Figures S25–S54). 3 Structural assignments Our research continued with a structural study, implemented by means of DFT calculations, solution (VT) NMR techniques, IR (KBr) spectroscopy and TEM analysis. 3.1 Assignments

• realised by covalent and/or (carboxyl/amino) ionic trimerisations, to recommend two G-1 N-substituted melamine dendrons with piperzine-1,4-diyl (linkers) and 4-(n-octyloxyphenyl)amino (peripheral units), D-Cl and D-N

  NH, as promising scaffolds for future dendritic elaborations. Tandem DFT-(VT) NMR

Dipolar addition to cyclic vinyl sulfones leading to dual conformation tricycles

• Steven S. Y. Wong,
• Michael G. Brant,
• Christopher Barr,
• Allen G. Oliver and
• Jeremy E. Wulff

Beilstein J. Org. Chem. 2013, 9, 1419–1425, doi:10.3762/bjoc.9.159

• -broadening in the NMR spectra was found to depend on the presence of substitution next to the inverting nitrogen center. Keywords: DFT calculations; dipolar addition; fluxional behavior; sulfones; VT NMR; Introduction The 1,3-dipolar cycloaddition [1][2][3] represents a powerful methodology for the

• the regio- and stereochemical outcome of the cycloaddition as that indicated for structure 3. This structural analysis was subsequently confirmed by X-ray crystallographic analysis of 3a (Figure 1) [36]. Further VT NMR studies of 3a in CDCl3 (Figure 2B) revealed a substantial broadening of several key

• and DEPT-135 spectra for all new compounds, VT-NMR data and 2D NMR spectra for 3a, crystallographic data for 3a, and absolute energies and Cartesian coordinates for calculated conformers. Supporting Information File 90: Detailed measurement data. Acknowledgements We gratefully acknowledge the