Synthesis of enantiomerically pure 4-polyfluoromethyl-4-hydroxy-homoprolines by intramolecular cyclization of 6-amino-5-polyfluoromethyl-hex-2-enoic acids

An effective route to racemic and enantiopure 4-polyfluoromethyl-4-hydroxy-homoprolines was developed based on readily available 2-alkoxyvinyl-polyfluoromethyl ketones. Key step of the synthesis was a diastereoselective heterocyclization of 6-amino-5-polyfluoromethyl-hex-2-enoic acids under acidic conditions. The absolute configuration of the stereogenic centers was determined by X-ray.