Approaches to Enantiomerically Pure 3,4-Dihydro-2H-1-Benzopyran-3-Amines

Single enantiomers of functionalised benzopyran-3-amines are widely used in the pharmaceutical industry as building blocks or intermediates in the synthesis of drugs acting as 5-hydroxytryptamine and dopamine receptor ligands, as well as inhibitors of dopamine β-monooxygenase. Several approaches for the preparation of the key benzopyran-3-amine intermediates in optically pure form are discussed, including synthesis and resolution of racemic mixtures, application of starting materials from the chiral pool, asymmetric synthesis and chromatographic techniques. Several examples of some larger scale production processes are provided, together with a discussion of the advantages and limitations of each approach.