Spatial arrangements of cyclodextrin host–guest complexes in solution studied by ¹³C NMR and molecular modelling

• Konstantin Lebedinskiy,
• Ivan Barvík,
• Zdeněk Tošner,
• Ivana Císařová,
• Jindřich Jindřich and
• Radim Hrdina

Beilstein J. Org. Chem. 2024, 20, 331–335, doi:10.3762/bjoc.20.33

• ). Having established the method, we chose various cyclic compounds (noradamantane, adamantane, cyclohexane derivatives) with desired symmetry and measured NMR spectra of these guest molecules (2–8) in α-cyclodextrin and cyclodextrins with a larger cavity (β-CD and γ-CD, Figure 4). In all cases, the 1H NMR

Strong hyperconjugative interactions limit solvent and substituent influence on conformational equilibrium: the case of cis-2-halocyclohexylamines

• Camila B. Francisco,
• Cleverton S. Fernandes,
• Ulisses Z. de Melo,
• Roberto Rittner,
• Gisele F. Gauze and
• Ernani A. Basso

Beilstein J. Org. Chem. 2019, 15, 818–829, doi:10.3762/bjoc.15.79

• preference for the ea conformer in cis-2-halocyclohexylamines, being strong enough to restrain the shift in the equilibrium due to other factors such as steric repulsion or solvent effects. Keywords: conformational equilibrium; cyclohexane derivatives; dynamic NMR; hyperconjugation; principal component

• halogen size. Instead, the equilibrium is influenced by solute–solvent hydrogen bonding with the hydroxy group. Besides the classical effects, interactions such as hyperconjugation has been pointed out as relevant in several studies involving cyclohexane derivatives [4][12][15][16][17][18][19][20]. Since

Gram-scale preparation of negative-type liquid crystals with a CF₂CF₂-carbocycle unit via an improved short-step synthetic protocol

• Tatsuya Kumon,
• Shohei Hashishita,
• Takumi Kida,
• Shigeyuki Yamada,
• Takashi Ishihara and
• Tsutomu Konno

Beilstein J. Org. Chem. 2018, 14, 148–154, doi:10.3762/bjoc.14.10

• determined to be the cis-isomer in both cases. Conclusion In summary, we demonstrated the efficient short-step, gram-scale preparation of tetrafluorinated cyclohexadiene or cyclohexane derivatives, which are very promising negative-type LC molecules, starting from commercially available dimethyl 2,2,3,3

• -tetrafluorosuccinate (7). A total of only five or six steps were required for the synthesis of the cyclohexadiene or cyclohexane derivatives, respectively. It should also be noted that the present reaction pathways did not require specific techniques or sensitive reagents, and gram-scale preparation was successfully

(Thio)urea-mediated synthesis of functionalized six-membered rings with multiple chiral centers

• Giorgos Koutoulogenis,
• Nikolaos Kaplaneris and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2016, 12, 462–495, doi:10.3762/bjoc.12.48

Topochemical control of the photodimerization of aromatic compounds by γ-cyclodextrin thioethers in aqueous solution

• Hai Ming Wang and
• Gerhard Wenz

Beilstein J. Org. Chem. 2013, 9, 1858–1866, doi:10.3762/bjoc.9.217

• , which are able to solubilize hydrophobic, nearly insoluble guest molecules, such as camptothecin [20], 1,4-dihydroxyanthraquinone [21], betulin [22], benzene and cyclohexane derivatives [23], and even C60 [24] in water. Furthermore, their respective γ-CD thioethers form highly water-soluble 1:2

Space filling of β-cyclodextrin and β-cyclodextrin derivatives by volatile hydrophobic guests

• Sophie Fourmentin,
• Anca Ciobanu,
• David Landy and
• Gerhard Wenz

Beilstein J. Org. Chem. 2013, 9, 1185–1191, doi:10.3762/bjoc.9.133

• VOCs. To demonstrate their versatility, two homologous series of volatile hydrophobic benzene and cyclohexane derivatives were chosen. These guests do not contain any hydrophilic substituents, therefore no attractive or repulsive polar interaction had to be taken into account. Since static headspace

• corresponding cyclohexane derivatives showed indeed a slope similar to the benzene derivatives, but free enthalpies more negative by ΔΔG°= 2 kJ mol−1, which was attributed to the larger diameter of cyclohexane compared to benzene filling the β-CD cavity more completely. For taking the space filling of the CD

• positions of β-CD. Our binding data are well described by the space filling of the cavity, as defined either by the number of carbons n, the molecular volume of the guest VG or by molecular modeling. Experimental Materials Benzene and cyclohexane derivatives were purchased from Aldrich, β-CD and

Asymmetric desymmetrization of meso-diols by C₂-symmetric chiral 4-pyrrolidinopyridines

• Hartmut Schedel,
• Keizo Kan,
• Yoshihiro Ueda,
• Kenji Mishiro,
• Keisuke Yoshida,
• Takumi Furuta and
• Takeo Kawabata

Beilstein J. Org. Chem. 2012, 8, 1778–1787, doi:10.3762/bjoc.8.203

• molecular modeling study. It is also anticipated that an axial-OH may be the better hydrogen-bond donor than an equatorial-OH, according to the reported higher acidity of the axial hydroxy groups of cyclohexane derivatives [39]. An alternative model for the transition-state assembly is shown in Figure 3

Donor-acceptor substituted phenylethynyltriphenylenes – excited state intramolecular charge transfer, solvatochromic absorption and fluorescence emission

• Ritesh Nandy and
• Sethuraman Sankararaman

Beilstein J. Org. Chem. 2010, 6, 992–1001, doi:10.3762/bjoc.6.112

• Stokes shift of nearly 130 nm (7828 cm−1) in DMSO in comparison to that observed in cyclohexane. Derivatives bearing carbonyl substituents (1d–e) showed large Stokes shift in polar protic solvents such as ethanol and isopropyl alcohol, presumeably due to the hydrogen bonding stabilization of the excited

An expedient synthesis of 5-n-alkylresorcinols and novel 5-n-alkylresorcinol haptens

• Kirsti Parikka and
• Kristiina Wähälä

Beilstein J. Org. Chem. 2009, 5, No. 22, doi:10.3762/bjoc.5.22

• -dimethoxybenzaldehyde (18–48% yields whenever reported) [22][23][24][25][26]. Additional synthetic methods have been developed for shorter chain AR (cyclohexane derivatives in 61–66% yield [27]. A recent Wittig approach utilises the ozonolysis product of a pentadecylresorcinol (C15