Efficient Synthesis of Allylic Amines from α-Aminoalkyl Cuprates and Enol Triflates

摘要

The reaction of α-aminoalkyl cuprates with enol triflates affords an efficient synthesis of allylic amines. Although cuprates containing nontransferable ligands gave low yields of allylic amines and only a single group is transferred from the 2 RLi/CuCN reagent, the unused ligand can be recovered. Regiospecific generation of enol triflates provides a regiocontrolled route to allylic amines which may be problematic in Pd-promoted reactions. In addition, the Pd/CuCN promoted coupling of α-aminoalkyl lithium reagents with aryl iodides is not readily extended to vinyl iodides or bromides (yield 30%). Consequently, the α-aminoalkyl cuprate/vinyl triflate and (α-aminoalkyl)lithium/aryl iodide couplings provide complementary solutions to the coupling of α-metalated amines with sp-carbon centers. Although sensitive to steric factors in the enol triflate and restricted to amines with functional groups compatible with carbanion formation, the method is extremely versatile with regard to substitution patterns in both the substrate and α-aminoalkyl cuprate reagent and should provide a versatile synthetic route to a wide range of cyclic and acyclic allylic amines.