N-Glycosides of indigo, indirubin, and isoindigo: blue, red, and yellow sugars and their cancerostatic activity

• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 2840–2869, doi:10.3762/bjoc.20.240

• instead of 1 h). Interestingly, in contrast to N-glycosides 41a–d, only one geometrical isomer was formed. This result is surprising, as the carbohydrate moiety is located far away from the double bond and unlikely exerts a stereochemical effect. As the aldol condensation is irreversible once the double

Synthesis of (−)-halichonic acid and (−)-halichonic acid B

• Keith P. Reber and
• Emma L. Niner

Beilstein J. Org. Chem. 2022, 18, 1629–1635, doi:10.3762/bjoc.18.174

• mobile phase contained approximately 2% triethylamine as a basic additive. However, it is also possible to use crude 7 in the subsequent cyclization step without significantly affecting isolated yields. 1H NMR analysis showed that 7 was formed as a single geometrical isomer; although the imine

Photophysical, photostability, and ROS generation properties of new trifluoromethylated quinoline-phenol Schiff bases

• Inaiá O. Rocha,
• Yuri G. Kappenberg,
• Wilian C. Rosa,
• Clarissa P. Frizzo,
• Nilo Zanatta,
• Marcos A. P. Martins,
• Isadora Tisoco,
• Bernardo A. Iglesias and
• Helio G. Bonacorso

Beilstein J. Org. Chem. 2021, 17, 2799–2811, doi:10.3762/bjoc.17.191

• [22]. Moreover, the E geometrical isomer in the –CH=N- double bond has a higher percentage when in dimethyl sulfoxide-d6 solution. On the other hand, the Z isomer can be stabilized in less polar solvents by an intramolecular hydrogen bond. In the present study, the spectral data were recorded in CDCl3

Cuevaenes C–E: Three new triene carboxylic derivatives from Streptomyces sp. LZ35ΔgdmAI

• Jing-Jing Deng,
• Chun-Hua Lu,
• Yao-Yao Li,
• Shan-Ren Li and
• Yue-Mao Shen

Beilstein J. Org. Chem. 2014, 10, 858–862, doi:10.3762/bjoc.10.82

• ; geometrical isomer; natural products; Streptomyces sp. LZ35; Introduction Cuevaenes are polyketides containing 3-hydroxybenzoic acid (3-HBA). Only 4 naturally occurring cuevaenes are described. Cuevaenes A and B were isolated from Streptomyces sp. HKI 0180 fifteen years ago and display moderate antibacterial

• (J = 15.4 Hz) and the strong NOE correlations from 3-H to 6a-H3, 7-H and19-H, and from 4a-H3 to 5-H. Two conformations were observed in the NOE spectrum of 3 due to the rotation around the C-5/C-6 single bond (Figure 2). Therefore, compound 3 was determined to be the geometrical isomer of 1

Fused bicyclic piperidines and dihydropyridines by dearomatising cyclisation of the enolates of nicotinyl-substituted esters and ketones

• Heloise Brice,
• Jonathan Clayden and
• Stuart D. Hamilton

Beilstein J. Org. Chem. 2010, 6, No. 22, doi:10.3762/bjoc.6.22

• it into a silyl enol ether 9. Silyl enol ethers and ketene acetals are known to add effectively to pyridinium species in an intermolecular manner [42][43][44][45][46]. Thus 7 was converted to silyl enol ether 9 in excellent yield under standard conditions. A single geometrical isomer was obtained