(4,4-Difluoro-4-bora-3a,4a,-diaza-s-indacen-3-yl)acetaldehyde: Synthesis and Chemical Properties

A reaction of 3,5-dimethylborondipyrromethene 3 with the DMF dimethylacetal gives rise to monoenamine 4. The latter is converted to the corresponding aldehyde 5. A considerable contribution of the enolic form of the aldehyde allows preparing numerous 3-vinyl substituted borondipyrromethenes and some heterocyclic derivatives. A reaction of the aldehyde 5 with tertiary aliphatic amines and the consecutive Hofmann-type decomposition of the intermediary quaternary salt give rise to the corresponding dialkylaminovinyl derivatives.