Copper catalyzed enantioselective allylic substitution by MeMgX

Methyl Grignard undergoes highly regio (>90/10) and enantioselective (ee 91–96%) copper catalyzed allylic substitution on cinnamyl-type chlorides. CuBr (3%) and 3.3% of a chiral phosphoramidite ligand are sufficient for a complete reaction. The synthesis of a precursor of (+)-Naproxen is described. The reaction can be extended to alkyl substituted allylic chlorides (ee 72%).