Synthesis of Enantiopure Benzyl Homoallylamines by Indium-Mediated Barbier-Type Allylation Combined with Enzymatic Kinetic Resolution: Towards the Chemoenzymatic Synthesis of N-Containing Heterocycles

Barbier-type indium-mediated allylations of different N,N(dimethylsulfamoyl)-protected aldimines with a number of allyl bromides followed by high-yielding deprotection afforded allylic amines in good to excellent yields. The racemic amines were then subjected to enzymatic kinetic resolution in order to obtain the corresponding (S)-amines and (R)-amides. When acyl donors with a terminal double bond were applied in the enzymatic kinetic resolution, the product amide could be converted into unsaturated lactams in a straightforward manner by utilizing ring-closing metathesis. Furthermore, the enantiopure (S)-1-phenylbut-3-enylamine was converted into the corresponding diallylamine, which was subjected to ring-closing metathesis to yield a substituted dehydropiperidine mimicking a number of natural products.