α-Ketoglutaric acid in Ugi reactions and Ugi/aza-Wittig tandem reactions

• Vladyslav O. Honcharov,
• Yana I. Sakhno,
• Olena H. Shvets,
• Vyacheslav E. Saraev,
• Svitlana V. Shishkina,
• Tetyana V. Shcherbakova and
• Valentyn A. Chebanov

Beilstein J. Org. Chem. 2025, 21, 2021–2029, doi:10.3762/bjoc.21.157

• compared to compounds 5, which can be clearly seen in the spectrum of compound 8h with both substituted ortho-positions of the amine moiety. In our opinion, this indicates the presence of rotamerism [59][60] caused by the restricted rotation of the sterically hindered amide group. The 1H NMR spectra of

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

• solution, for example, asymmetric vs propeller (C3-symmetric) [30][36][45][46], “dendritic choreography” [47], “open-gates closed-gates” frontier rotamerism [31] and “in out” axial chirality [33]. In addition, in the targeted G-2 dendrimers (Figure 1), different connections of branches around the core

• solution, the reaction conditions were found mandatory to the high solvation of the G-0 and G-1 dendrons exhibiting a major (anti–anti) (parallel) rotamerism of the peripheral 4-(n-octyloxy)phenyl units about the C(s-triazine)–N(exocyclic) partial double bonds. The final iterative synthetic step was

• . The structural variety of the covalent dendritic elaboration around the m-trivalent cores (1,4-phenylene over piperazin-1,4-diyl adjacent linkers, propeller over asymmetric rotamerism of the angular over linear connectivity) modulated the degree of nano-aggregation. Experimental General All reagents

Conformational equilibrium in supramolecular chemistry: Dibutyltriuret case

• Karina Mroczyńska,
• Małgorzata Kaczorowska,
• Erkki Kolehmainen,
• Ireneusz Grubecki,
• Marek Pietrzak and
• Borys Ośmiałowski

Beilstein J. Org. Chem. 2015, 11, 2105–2116, doi:10.3762/bjoc.11.227

• ; hydrogen bonding; NMR; rotamerism; supramolecular chemistry; Introduction The hydrogen bond (HB) is one of the most common non-covalent interactions. Since it stabilizes, for example, the double helix of DNA and influences peptide folding it is quite reasonable to assume that HBing is crucial for

• interactions [41] that act diagonally between neighbouring hydrogen bonding sites. The breakage of single intramolecular hydrogen bonding upon association leading to rotamerism was our motivation to search for more complex systems than previously reported [2][9][10]. Since the amide group is common in

• ) separate curves overlap. One of these exhibits a decrease of the chemical shift in the beginning of titration with relatively small CIS value and reaches its plateau relatively fast. The said decrease of the chemical shift may only be caused by the rotamerism and change of intra- to intermolecular hydrogen