When examining benzoxazoles bearing electron-withdrawing substituents, however, the desired alkylation products were not obtained using the standard protocol described above. We postulated that the increased acidity of benzoxazole's C-2 C-H bond could lead to deleterious side reactions with 1,5-cyclooctadiene (COD) from the nickel pre-catalyst, resulting in unproductive off-cycle intermediates. The diminished reactivity of benzoxazoles bearing electron-withdrawing groups has similarly been observed by Ong and co-workers in their study of hydroarylation of cyclic dienes. The inhibitory effect of COD in C-H activations was previously described by our laboratory in the development of alkyne hydroarylation reactions involving LLHT pathways. Such phenomenon originates from the participation of COD in a competing LLHT C-H activation that results in a stable off-cycle p-allyl complex that minimizes the concentration of the active catalyst for productive catalysis. This side reaction was prevented by employing 1,5-hexadiene-supported nickel pre-catalysts leading to a more efficient alkyne hydroarylation at reduced temperatures. Motivated by this finding, we set out to develop the synthesis for NHC nickel complexes stabilized with 1,5-hexadiene from easily accessible nickel precursors under operationally simple condition. Inspired by work done by Wilke and co-workers on the synthesis of 'bis(olefin)nickel-ligand complex' as well as Belderrain and Nicasio's nickel bis-styrene complex, we anticipated that ligand exchange from COD to 1,5-hexadiene followed by trapping with free NHC ligands would allow facile access to a variety of sterically demanding NHC nickel complexes. Using this approach (see supporting information), we were able to synthesize 1,5-hexadiene supported nickel complexes bearing IMes, IPr Me , IPr* OMe as well as the optimal ligand for the enantioselective transformation described above (L5 in Scheme 2), whose structure was unambiguously confirmed using x-ray crystallography (Scheme 3). With these novel catalysts in hand, we first tested their reactivity using benzoxazole (1a), and comparable results were obtained. Moreover, the synthesis of enantioenriched alkylation products could be carried out using as low as 2.5 mol % L5-Ni(C6H10) at 1.0 mmol scale without diminished enantioselectivity. We employed this catalyst in previously problematic substrates including those that feature electron-withdrawing substituents. While the in-situ-generated chiral catalyst at 10 mol % loading gave no reaction, 1p and 1q underwent alkylation smoothly to give desired products using the discrete nickel catalyst L5-Ni(C6H10), where excellent enantioselectivities and clean reaction profiles were observed. Most surprisingly, products arising from chemoselective C-H functionalization were observed as the sole product with 93:7 e.r. in the presence of competing C-Cl bonds susceptible to facile activation with low-valent nickel catalysts (1r). Lastly, substituted indoles and azaindoles could also be included into the scope simply by raising the reaction temperature to 60 o C (1s-u), thus demonstrating the broad functional group compatibility of this Lewis acid free approach to C2 alkylated heteroarenes. Scheme 4. Broaden the scope with discrete L5-Ni(C6H10) catalyst. Reactions were performed at 0.10 mmol scale unless noted. Yields were reported for isolated products. a Reaction was carried out with 2.5 mol % catalyst at 0.4M in PhMe. b Reaction was carried out using 2.0 equiv. nbe at 60 °C.