This account focuses on the application of ω-transaminases, lyases, and oxidases for the preparation of amines considering mainly work from our own lab. Examples are given to access α-chiral primary amines from the corresponding ketones as well as terminal amines from primary alcohols via a two-step biocascade. 2,6-Disubstituted piperidines, as examples for secondary amines, are prepared by biocatalytical regioselective asymmetric monoamination of designated diketones followed by spontaneous ring closure and a subsequent diastereoselective reduction step. Optically pure tert-amines such as berbines and N-methyl benzylisoquinolines are obtained by kinetic resolution via an enantioselective aerobic oxidative C–C bond formation.

Deracemization, that is, the transformation of a racemate into a single product enantiomer with theoretically 100 % conversion and 100 % ee, is an appealing but also challenging option for asymmetric synthesis. Herein a novel chemo-enzymatic deracemization concept by a cascade is described: the pathway involves two enantioselective oxidation steps and one non-stereoselective reduction step, enabling stereoinversion and a simultaneous kinetic resolution. The concept was exemplified for the transformation of rac-benzylisoquinolines to optically pure (S)-berbines. The racemic substrates were transformed to optically pure products (ee>97 %) with up to 98 % conversion and up to 88 % yield of isolated product.

(S)-Strictosidine represents the first key intermediate in the biosynthesis of several pharmaceutically relevant monoterpenoid indole alkaloids. Optically pure C3-methyl-substituted strictosidine derivatives were prepared by setting up the two stereogenic centers at the β-carboline core via two enzymatic steps catalyzed by the enzymes transaminase and strictosidine synthase in a one-pot cascade fashion. The two enzymatic steps were performed simultaneously as well as in a stepwise fashion. The amination of the prochiral ketones led to optically pure amines with up to >98% enantiomeric excess. Depending on the enzyme used, the (S)- and (R)-enantiomers were prepared in most cases. Selected amines were then condensed with secologanin in a Pictet–Spengler reaction catalyzed by strictosidine synthase leading to diastereomerically pure products (>98% diastereomeric excess).

Stereoselective methods for the synthesis of tetrahydro‐ß‐carbolines are of significant interest due to the broad spectrum of biological activity of the target molecules. In the plant kingdom, strictosidine synthases catalyze the C−C coupling through a Pictet–Spengler reaction of tryptamine and secologanin to exclusively form the (S)‐configured tetrahydro‐ß‐carboline (S)‐strictosidine. Investigating the biocatalytic Pictet–Spengler reaction of tryptamine with small‐molecular‐weight aliphatic aldehydes revealed that the strictosidine synthases give unexpectedly access to the (R)‐configured product. Developing an efficient expression method for the enzyme allowed the preparative transformation of various aldehydes, giving the products with up to >98 % ee. With this tool in hand, a chemoenzymatic two‐step synthesis of (R)‐harmicine was achieved, giving (R)‐harmicine in 67 % overall yield in optically pure form.