Among the hydrogen atom transfer reagents tested, the di-tert-butyl peroxide (DTBP) showed particular activity in yielding the desired coupling product. Other peroxides and NFSI, and selectflour all gave low yield and low enantioselectivity or racemic product (entries 9-12. also see Supplementary Tables ). Ligand study showed that other structurally related bisoxazoline ligands (L1, L2, L4) are also effective, but with lower enantioselectivities (entries 13-15). However, when the amount of alkylarene substrate 1a was reduced to 2.0 equiv., the yield of product 3a dropped dramatically (entry 16). It is worth mentioning that most of the unreacted ethylbenzene could be recovered (55%) after the reaction. With the optimized reaction conditions in hand, we investigate the alkylarene substrate scope of the asymmetric amination of benzylic C(sp 3 )-H bonds. As shown in the Scheme 2, the electron-withdrawing substituents (Cl, Br, I) in alkylarene substrates were well-tolerated, giving the desired products (3a-3i) in good yields with high enantioselectivities (up to 97:3 er). The halide substituents in the products allowed an additional opportunity for further synthetic manipulations/transformations. The alkyl group on the benzene ring of alkylarenes 1 has a little effect on the yield and enantioselectivity of the reaction, and the substrate 1m having a long alkyl group afforded the highest enantioselectivity (99:1 er). For isobutylbenzene 1n, which contains both benzylic and tertiary aliphatic C-H bonds, the reaction occurred majorly at the benzylic position (3n, 56% yield, 94:6 er), but was also accompanied by a reaction at tertiary aliphatic C-H bond (18% yield). Notably, the reaction exhibited good compatibility with the functional groups on the alkyl chain of the substrates. The alkylarenes having esters (3p, 3q, 3u, 3v), ether (3r), olefin (3s), amine (3t) and halide (3w) on the alkyl chains all gave the corresponding amination products with high enantioselectivities. Cyclic alkylarenes containing six-membered rings, including the tetralin and the common pharmacophore chroman, were also compatible in the reaction and produced related products (3z, 3aa).