Synthesis of Trifluoromethylated 3-(3-Pyrazolyl)indole-N-glycosides and their Cytotoxic Activity against Human Keratinocytes (HaCaT)

The first 3-(3-pyrazolyl)indole-N-glycosides were prepared starting from indole-N-glycosides by conversion with 4-ethoxy-1,1,1-trifluorobut-3-en-2-one and following cyclization with hydrazine. The cytotoxic activity of the products against human keratinocytes (HaCaT) was studied.     

Synthesis of 1,3,5-tricarbonyl derivatives by condensation of 1,3-bis(silyl enol ethers) with acid chlorides

A variety of 1,3,5-tricarbonyl derivatives were prepared by reaction of 1,3-bis(silyl enol ethers) with acid chlorides under mild conditions. This includes reactions of both aromatic and aliphatic acid chlorides and bis(acid chlorides). The yields vary depending on the type of acid chloride employed.     

Novel Small-Molecule Hybrid-Antibacterial Agents against S. aureus and MRSA Strains

Ongoing resistance developments against antibiotics that also affect last-resort antibiotics require novel antibacterial compounds. Strategies to discover such novel structures have been dimerization or hybridization of known antibacterial agents. We found novel antibacterial agents by dimerization of indols and hybridization with carbazoles. They were obtained in a simple one-pot reaction as bisindole tetrahydrocarbazoles. Further oxidation led to bisindole carbazoles with varied substitutions of both the indole and the carbazole scaffold. Both the tetrahydrocarbazoles and the carbazoles have been evaluated in various S. aureus strains, including MRSA strains. Those 5-cyano substituted derivatives showed best activities as determined by MIC values. The tetrahydrocarbazoles partly exceed the activity of the carbazole compounds and thus the activity of the used standard antibiotics. Thus, promising lead compounds could be identified for further studies.     

Synthesis of the first deprotected indigo N-glycosides (blue sugars) by reductive glycosylation of dehydroindigo

The first deprotected indigo N-glycosides (blue sugars) have been prepared by reaction of dehydroindigo with in situ generated rhamnosyl, glucosyl and mannosyl iodide.