Asymmetrische Organokatalyse zu Alpha-Fluorierung von Aldehyden und Ketonen und zur Synthese von Cyclohexencarbaldehyden via Dominoreaktionen

Chiral secondary amines play a crucial role in the fast growing field of organocatalysis. Due to their two activation modes of several carbonyl compounds, namely enamine catalysis (HOMO-raising) and iminiumion catalysis (LUMO-lowering), they are capable to catalyze a broad variety of different reactions, which explains increasing application of these catalysts in organic synthesis. In particular, amine-catalyzed domino reactions can be easily designed by combination of the enamine and iminiumion activation steps to assemble complex structures bearing multiple stereocentres from simple precursors very efficiently. In this work the amine-catalysis was used to open up the first direct organocatalyzed entry to alpha-fluorinated aldehydes and ketones. Furthermore, polyfunctionalized cyclohexene carbaldehydes were synthesized via an organocatalyzed triple cascade creating three new carbon-carbon bonds and up to four new stereocentres with high diastereo- and complete enantiocontrol in one step. This method could be extended by an intramolecular Diels-Alder reaction leading to the tricyclic carbon frameworks in a one-pot operation