Organocatalytic Fluorogenic Synthesis of Chromenes.

Two fluorescent derivatives of 2-amino-3-carbonitrile-4H-chromene were synthesized by means of a fluorogenic Michael addition of dimedone to dicyano alkene labeled BODIPY derivatives. Different organocatalysts were used in different conditions to obtain compounds 3 and 4 in good yield (up to 65% and 85%) and moderate enantiomeric excess (51% and 41% ee, respectively). This work provides the first example of an enantioselective organocatalytic conversion combined with fluorogenesis.