Generation of potent antibacterial compounds through enzymatic and chemical modifications of the trans-δ-viniferin scaffold

Stilbene dimers are well-known for their diverse biological activities. In particular, previous studies have demonstrated the high antibacterial potential of a series of trans-δ-viniferin-related compounds against gram-positive bacteria such as Staphylococcus aureus. The trans-δ-viniferin scaffold has multiple chemical functions and can therefore be modified in various ways to generate derivatives. Here we report the synthesis of 40 derivatives obtained by light isomerization, O-methylation, halogenation and dimerization of other stilbene monomers. The antibacterial activities of all generated trans-δ-viniferin derivatives were evaluated against S. aureus and information on their structure-activity relationships (SAR) was obtained using a linear regression model. Our results show how several parameters, such as the O-methylation pattern and the presence of halogen atoms at specific positions, can determine the antibacterial activity. Taken together, these results can serve as a starting point for further SAR investigations.

9,9-Bis[4-(N-aryl)phenyl]methylidene-xanthylidene Derivatives Displaying Mechano-, Crystallo-, and Thermochromism

Tetraphenylethylene (TPE) derivatives bearing a xanthene moiety are of interest because they have novel optical properties. 9,9-Bis[4-(N,N-diphenylamino)phenyl] and 9,9-bis[4-(9-carbazolyl)-phenyl]methylidene-xanthylidenes 3 and 4 were synthesized using Suzuki-Miyaura coupling of 9,9-dibromomethylidene-xanthylidene with the corresponding boronic acids. Diphenylamino derivative 3 exhibits mechanochromism and mechanofluorochromism (MC and MFC) reflected in absorption and fluorescence color changes. In contrast, carbazolyl derivative 4 displays thermo- and crystallo-chromism in addition to MC and MFC in the solid state. Powder X-ray diffraction and single crystal X-ray crystallographic analysis reveal that the solid state photophysical properties of these substances are governed by conformational changes rather by the creation of planar π-conjugation extended geometries.

Iridium-Catalyzed Aerobic Coupling of Salicylaldehydes with Alkynes: A Remarkable Switch of Oxacyclic Product

The iridium(III)/copper(II)-catalyzed dehydrogenative coupling of salicylaldehydes with internal alkynes proceeds efficiently under atmospheric oxygen through aldehyde C-H bond cleavage and decarbonylation. A variety of benzofuran derivatives can be synthesized by the environmentally benign procedure. DFT calculations suggest that this unique transformation involves the facile deinsertion of CO in the key metallacycle intermediate, which is in marked contrast to the corresponding rhodium(III) catalysis that leads to CO-retentive chromone derivatives.

Further insight into the photochemical behavior of 3-aryl-N-(arylsulfonyl)propiolamides: tunable synthetic route to phenanthrenes

Reported herein is further insight into the photochemical behaviour of 3-aryl-N-(arylsulfonyl)-propiolamides, which provides a straightforward way to access meaningful phenanthrenes.