In parallel to optimization efforts for the first arylation of 14a, a readily available RAE of commercial acid 23 was evaluated for the pivotal second arylation (Table ). After extensive screening, a 46% yield of the 1,1-diarylated product 25 (Table , entry 1) was achieved using 5-bromopyrimidine 24. The greatest hurdle to overcome in this effort was to suppress the formation of bis-cyclobutane 26 resulting from dimerization of the transient radical derived from reduction of 23-RAE which formed in 34% yield even in the optimized conditions. This type of homocoupling has also been encountered as a main side-product by the Weix group during their studies on benzylic cyclopropane coupling (use of one of their optimized ligands did not work in these couplings, see SI). The final conditions arose after extensive screening, commencing with previously reported conditions for tertiary redox active ester arylation (on non-benzylic systems) wherein only trace product was observed (entry 2-3), suggesting significant differences in benzylic cyclobutyl radicals. Employing conditions from successful monoarylation (Table , entry 1) delivered only 4% yield of 25 (entry 4). Ultimately, the choice of ligand proved crucial to achieve this demanding transformation with the identification of L10 as uniquely suited. For the sake of convenience and reproducibility Ni(L10)Cl 2 precatalyst was employed (entry 1), however, adding the ligand and nickel precursors separately gave similar results (entry 5, 44% yield). Ligand screening revealed the importance of the substitution pattern on the 2,2'-bipyridine backbone. Thus, substitution at the 4-position was fruitless (L1, L2, entries 6-7) and substitution at the 6-position was critical, with L3 (bearing two methyl groups) giving a 28% yield (entry 8). Further modifications to the backbone did not significantly improve results (entry 9-15). Ultimately L10, first reported by the Hazari group, proved superior to all other ligands tested, presumably stemming from the different geometry of Ni-Ar complexes formed with this ligand (tetrahedral vs. square planar). As usual, the addition of Ag-salt was critical (deletion of AgOTf from the reaction resulted in 7% yield, entry 16). Finally, omitting LiClO 4 resulted in 26% yield (entry 17), and switching electrolytes to TBABF 4 or TEABF 4 gave slightly lower yields (44% and 38%, entry 18). Such electrolytes could be useful alternatives to LiClO 4 for potential large scale applications. In scenarios where material is needed rapidly and a commercial ligand is required, L3 provided 37% yield when enlisting 40 mol% of nickel catalyst (entry 19). Overall, the above procedures for sequential arylation are quite similar in terms of general procedure, differing only in the silver salt, electrolyte, and ligand. The setup takes place without any precautions to exclude air or moisture, is complete within 4-5 h, and the workup/quench is no different than a canonical organic reaction (see SI for photographically illustrated procedures).