Fluoreszenzfarbstoffe in der Natur

Cumarines as fluorescent substances are widely spread in living nature and can be found in different genera of plants and fungi. Due to their intensive fluorescence they can be easily observed. This gives the opportunity to make experiments with low costs, low complexity and without using toxic materials.     

Enantioselective N‐Heterocyclic Carbene Catalyzed Bis(enoate) Rauhut–Currier Reaction

While the enantioselective Rauhut–Currier reaction is established with bis(enone) substrates, it is yet to be reported with less electrophilic bis(enoate) substrates. By exploiting high‐nucleophilicity N‐heterocyclic carbenes, it is possible to achieve Rauhut–Currier reactions with these substrates. The reaction is demonstrated with a range of intramolecular reactions (20 examples) and six esterification/RC reaction cascades, which all proceed with high enantioselectivity (most >93:7 er).