The asymmetric synthesis of α-heterofunctionalized αand β-amino acid derivatives has been a heavily investigated topic over the last years, benefiting from the development of novel catalysis concepts as well as from the introduction of suited new precursor entities. Within this short review, we wish [a] I.

The enantioselective synthesis of a broad variety of novel differently functionalized α-halogenated α-aryl-β 2,2 -amino acid derivatives by means of an ammonium-salt-catalyzed asymmetric α-halogenation of isoxazolidin-5-ones was accomplished. Key to success to obtain high levels of enantioselectivities was the use of Maruoka’s spirocyclic binaphthyl-based ammonium salts, and detailed accompanying mechanistic studies using density functional theory methods revealed the key features for the catalyst–substrate interactions.