Modified N-acyl-homoserine lactones as chemical probes for the elucidation of plant-microbe interactions.

Gram-negative bacteria often use N-acyl-homoserine lactones (AHLs) as signal molecules to monitor their local population densities and to regulate gene-expression in a process called "Quorum Sensing" (QS). This cell-to-cell communication allows bacteria to adapt to environmental changes and to behave as multicellular communities. QS plays a key role in both bacterial virulence towards the host and symbiotic interactions with other organisms. Plants also perceive AHLs and respond to them with changes in gene expression or modifications in development. Herein, we report the synthesis of new AHL-derivatives for the investigation and identification of AHL-interacting proteins. We show that our new compounds are still recognised by different bacteria and that a novel biotin-tagged-AHL derivative interacts with a bacterial AHL receptor.

Pd-catalyzed assembly of spirooxindole natural products: a short synthesis of horsfiline.

The Pd-catalyzed intramolecular alpha-arylation of amides is applied to the synthesis of functionalized spirooxindoles. The substrate scope is evaluated, and the reaction is demonstrated to be useful for the assembly of spirooxindole natural products and derivatives thereof. As an application, a new synthesis of horsfiline 1 is presented, giving the natural product in only 4 steps from commercially available amino acid 12.