Synthesis of Thiazoline–Oxazoline Ligands and Their Application in Asymmetric Catalysis

A series of novel ligands incorporating oxazoline and thiazoline units were synthesized in high yield by employing a convergent route, in which the key step is a microwave‐assisted palladium‐catalyzed aryl amination. The new ligands were tested in the zinc‐catalyzed Friedel–Crafts alkylation of indole with trans ‐β‐nitrostyrene, inducing enantiomeric excess values of up to 69 %. The complete series of these ligands was also applied to the chromium‐catalyzed Nozaki–Hiyama–Kishi (NHK) allylation of benzaldehyde, affording enantiomeric excess values of up to 85 %. A crystal structure of the most successful ligand in this transformation bound to iron(III) was obtained and demonstrated a tridentate binding mode of the ligand. A transition state is proposed to account for the preferential formation of the ( R )‐enantiomer in the NHK reaction.