was obtained in 95% yield with 89% ee. We further modified the phosphine-attached aromatic ring where two methoxy substituents were employed to upturn the electrondonating capacity. The corresponding ligand L16 could indeed raise the reaction efficiency as 97% yield of 3a was observed while the ee value kept untouched compared to L13. In the end, L17 exhibited superior enantioselectivity (91% ee) in the asymmetric carbene coupling reaction without any interference for the yield (95% yield) in a comparable fashion to L15. Therefore, the optimal reaction conditions were identified as 10 mol% Pd(OAc)2, 12 mol% L17, 2.5 equivalent of Cs2CO3, 40 mol% TBAB, and 2.0 mL p-xylene at 50 o C for unambiguously confirmed as S-configuration by X-ray crystallography analysis. With the optimized reaction conditions established, we first focused on screening the scope of aryl bromides. Aryl bromides underwent this asymmetric carbene crossingcoupling reaction smoothly, delivering axially chiral alkylidenecyclobutanes of structural diversity in moderate to excellent yields with high enantioselectivities (54% to 96% yields, 89% to 95 % ee values). para-Substituted electron-donating (Me, n Hex, t Bu, OMe, TMS, Ph, C2H3) and electron-withdrawing groups (F, Cl, CF3, CO2Et) were all tolerated in the reaction, and the corresponding axially chiral products (3b-3l) were produced in 85% to Scheme 2. Substrate scope of aryl bromides.