Initial investigations on a template internal alkene
1 revealed that the reactions of
1 with Selectfluor, diethoxymethylsilane (DEMS), and NaHCO
3 in the presence of catalytic NiBr
2·DME with chiral bi-oxazoline (BiOx)
L1, pyridine-2,6-bis(oxazolines) (Pybox)
L2, or Bn-substituted bisoxazoline (Box)
L3 failed to afford any desired products (
Fig. 1,
Table 1, entries 1–3). Switching to the Ph-Box
L4 gave a 23% yield of the desired
β-F amide product
2 with exclusive regioselectivity and a promising enantiomeric excess (entry 4). Encouraged by these results, we further evaluated a series of chiral Ph-Box ligands (
L5-
L10). We found that an increase in the steric hindrance at the
gem‑disubstituted linker or the C5 substituents of Box ligands can improve the efficiency of this hydrofluorination reaction (entries 5–10). Remarkably, the C5-diphenyl substituted ligands (
R,
R)-
L8 and (
R,
R)-
L9 with bulky linkers significantly improved the yields and
ee, and (
R,
R)-
L9 proved to be optimal, affording product
2 in 74% yield and 97%
ee (entries 8 and 9). Further increasing the steric hindrance of the linker by installing two naphthalene methyl groups gave a new ligand (
R,
R)-
L10, nevertheless resulting in a dramatic decrease in yields (entry 10). As anticipated, the choice of solvent proved to be pivotal. Reactions conducted in DME or ethyl acetate yielded moderate yields, whereas no product was observed in cyclohexane (entries 11–13). The use of
N-fluorobenzenesulfonimide (NFSI) led to significant decreases in yields and
ee; nevertheless, no product was detected with
N-fluoropyridinium salt as a fluorinating agent (entries 14 and 15). While almost concurrently, Hong reported the nickel-catalyzed asymmetric hydrofluorination of unactivated alkenes utilizing (
S,
S)-
L3 and a
N-fluoropyridinium salt
via an ionic pathway. However, attempts to react alkenes with (
S,
S)-
L3/Selectfluor or (
R,
R)-
L9/
N-fluoropyridinium salt were unsuccessful (entries 3 and 15), indicating that different mechanisms are influenced by the backbone of chiral ligands and
F+ agents [
66]. Control experiments revealed that nickel catalyst, chiral ligand, silane, and base are all necessary for this transformation (entry 16). We identified the
β-CONH group is crucial for efficiency and regio-/stereo-selectivity, as no products were observed in cases involving alkenyl ketone (
1a), alkenyl ester (
1b), or tertiary amide (
1c). Additionally, alongside product
2, a small amount of side product lactam
2′ was detected in most cases.