(Pseudo)amide-linked oligosaccharide mimetics: molecular recognition and supramolecular properties

• José L. Jiménez Blanco,
• Fernando Ortega-Caballero,
• Carmen Ortiz Mellet and
• José M. García Fernández

Beilstein J. Org. Chem. 2010, 6, No. 20, doi:10.3762/bjoc.6.20

• ] that were found to form rigid secondary structures predetermined by the linkage position as evidenced from CD and NMR measurements. Moreover, conformational analysis by molecular modelling calculation on the β(1→2)-linked decamer 9 supported a helical arrangement, stabilised by a intramolecular

• and co-workers undertook the synthesis of carbopeptoids based on the oxetane template (Figure 7) [46][47][48]. Conformational analysis was carried out for two oxetane β-SAA hexamers with the 6-deoxy-L-altro and D-arabino configurations by means of detailed NMR and IR studies in combination with

• acid. Following the same objective, Xie’s group prepared orthogonally protected cyclic homo-oligomers with two to four SAA units that can be selectively or fully deprotected to afford macrocycles that can undergo further functionalisation (Figure 11) [55]. Conformational analysis by molecular modelling

[3.3]Dithia-bridged cyclophanes featuring a thienothiophene ring: synthesis, structures and conformational analysis

• Sabir H. Mashraqui,
• Yogesh Sanghvikar,
• Shailesh Ghadhigaonkar,
• Sukeerthi Kumar,
• Auke Meetsma and
• Elise Trân Huu Dâu

Beilstein J. Org. Chem. 2009, 5, No. 74, doi:10.3762/bjoc.5.74

• case of 11, also by single crystal X-ray crystallography. Conformational analysis by variable temperature NMR suggests that cyclophanes 7, 9 and 11 exhibit conformationally rigid bridges and rings at least up to 130 °C. Energy minimization of 11 revealed anti-11 to be the most stable conformation

• conformational analysis of thienothiophenophanes 7, 9 and 11 The 1H NMR (300 MHz) spectrum of dithia-cyclophane 7 revealed two AB spin systems (4H each) in the range of δ 3.21–4.30 due to the geminal couplings of the bridged –CH2- protons. A singlet centered at δ 2.31 accounted for the C3/C4 methyl groups. The

• former slightly displaced from the center of the latter. In order to evaluate the energy minimized conformations for 11, we performed the conformational analysis by random search Monte Carlo method [33] and optimized by PRCG Conjugated Gradient molecular mechanics minimization using the Macromodel

Ring strain and total syntheses of modified macrocycles of the isoplagiochin type

• Andreas Speicher,
• Timo Backes,
• Kerstin Hesidens and
• Jürgen Kolz

Beilstein J. Org. Chem. 2009, 5, No. 71, doi:10.3762/bjoc.5.71

• conformational analysis and MD investigations clearly confirmed the biaryl axis A to be configurationally stable at room temperature due to the second (more flexible) biaryl axis B, an (even more flexible) helical stilbene unit C and their combination with the ring-strain of the entire molecule. By experimental

Mitomycins syntheses: a recent update

• Jean-Christophe Andrez

Beilstein J. Org. Chem. 2009, 5, No. 33, doi:10.3762/bjoc.5.33

A stable enol from a 6-substituted benzanthrone and its unexpected behaviour under acidic conditions

• Marc Debeaux,
• Kai Brandhorst,
• Peter G. Jones,
• Henning Hopf,
• Jörg Grunenberg,
• Wolfgang Kowalsky and
• Hans-Hermann Johannes

Beilstein J. Org. Chem. 2009, 5, No. 31, doi:10.3762/bjoc.5.31

• the relevant molecules 4, 7 and 9–18 were obtained by first applying an extended conformational analysis using the OPLS2005 force field [12] together with a Monte Carlo torsional sampling as implemented in the Macromodel 9.5 program [13]. Each lowest energy conformation of 4, 7 and 9–18, respectively

A convenient allylsilane- N-acyliminium route toward indolizidine and quinolizidine alkaloids

• Roland Remuson

Beilstein J. Org. Chem. 2007, 3, No. 32, doi:10.1186/1860-5397-3-32

• synthesis of the four racemic diastereomers of this indolizidine and a conformational analysis of these diastereomers has been discussed. [36][37] Its identification as (5R,7S,9R)-5,7dimethylindolizidine has been firmly established. [38] We describe here the first asymmetric synthesis of this alkaloid; [39

A superior P-H phosphonite: Asymmetric allylic substitutions with fenchol- based palladium catalysts

• Bernd Goldfuss,
• Thomas Löschmann,
• Tina Kop-Weiershausen,
• Jörg Neudörfl and
• Frank Rominger

Beilstein J. Org. Chem. 2006, 2, No. 7, doi:10.1186/1860-5397-2-7

• the NH3 model nucleophile corresponds to the experimental R-alkylation product. The two most stable ONIOM(B3LYP/SDD(+ECP) (Pd) /6-31G* (C, H, O, N, P) : UFF) optimized transition structures with BIFOP-H, due to systematic conformational analysis (60° rotations at P-Pd). ZPE (unscaled) corrected total