Table . Alkyl amine additive evaluation for the cross-coupling reaction of phenol. %Vbur is a modern steric descriptor capturing the volume percent of a sphere that is occupied by the included atoms. The %Vbur Based on our hypothesis, nucleophiles that can compete with tert-butylamine for nickel coordination meet the prerequisites for successful cross-coupling. This is further supported by the observation that high tert-butylamine concentrations (2.6 equiv) lead to decreased reaction rates (Table and). Thus, nucleophiles of similar or higher nucleophilicity than phenol were thought to be compatible with our optimized reaction condition. Consequently, the scope of C(sp²)-O cross-coupling reactions was explored using a variety of electronically differentiated phenols (Figure ). Both electron-rich and electron-poor phenols were effectively cross-coupled, achieving good to excellent yields of the desired products 1-3. Additionally, aliphatic alcohols such as cyclopentanol (4) and hexanol (5), under the same reaction conditions, were also successfully employed as nucleophiles, providing high isolated yields. Next, we explored the synthetic versatility of using tert-butylamine as an additive in C(sp 2 )-N bond-forming reactions with a range of different nitrogen nucleophiles. Nucleophiles with pharmaceutical relevance, such as a lactam ( ), a carbamate (7), or sulfonamides, whether aryl (8) or alkyl (9), successfully underwent cross-coupling reactions, yielding the desired crosscoupled products in good to excellent yields. Moreover, anilines gave the desired products in good to excellent yields. Notably, electron-poor (10 and 11), electron-neutral (12), and electron-rich (13) anilines led to the efficient formation of the respective products. Heteroaromatic anilines were no exception, giving the desired products 14-16 in good to excellent yields. The steric hindrance exerted by alkyl groups in the ortho-position was well tolerated (17 and 18), even with isopropyl groups at both ortho-positions. Only 2,6-di-tert-butyl aniline was too sterically hindered to undergo the reaction effectively. The crosscoupling reactions with cyclic secondary anilines, such as 2,3-dihydroindole (19) and carbazole (20), were also successful, yielding the desired products in 95% and 65% isolated yields, respectively. Moreover, these cross-coupling reactions are compatible when five-membered heterocycles are employed as nucleophiles. For instance, pyrazoles can be employed, yielding the desired products 21 and 22 in good, isolated yields. Not surprisingly, more nucleophilic imines can be efficiently coupled as well. Benzophenone imine, a common ammonia surrogate in cross-coupling reactions, when employed as a nucleophile with ethyl 4-bromobenzoate as the model electrophile, yielded the desired product 23 in an excellent 92% isolated yield. Similarly, sulfoximines, which have recently gained increased attention as promising bioisosteres for sulfones and sulfonamides in drug discovery, 66 could be efficiently cross-coupled in excellent to near-quantitative yields. Alkyl-alkyl (24), alkyl-aryl (25), and aryl-aryl (26) sulfoximines were all effective as nucleophiles, providing the desired coupling products in good to excellent yields. It is to be noted here that these cross-coupling reactions are also effective in the presence of DABCO, an alternative and more expensive base, which precipitates from DMA upon protonation by the generated mineral acid (e.g., HBr). However, the use of tert-butylamine not only allows for faster reactions with lower equivalents (Table ) but enables precipitate-free reaction conditions, which may facilitate the scale-up of cross-coupling reactions under continuous flow conditions. The cross-coupling reactions are not limited to aryl halides; a range of (hetero)aryl halides covering (hetero)aromatic scaffolds privileged in drug discovery are equally compatible as electrophiles and did not require any additional optimization as exemplified using dimethylsulfoximine, anilines, and para-toluenesulfonamide as nucleophiles. Notably, nitrogen containing heterocycles often present difficulties in transition metal catalysis due to their propensity to coordinate and deactivate the catalyst. Such complications were not observed, and various heterocycles containing different substituents yielded the desired products 27-32 in very good to excellent yields. Importantly, the cross-coupling reactions were also effective when base-sensitive electrophiles (30 and 32) were used. Notably, the position of the C(sp 2 )-Br bond in the (hetero)aryl core had minimal influence, consistently providing the desired product in good to excellent yields. Furthermore, the introduction of more electron-donating para-substituents on the aryl halides was well tolerated, furnishing the desired products 33 and 34 in 92% and 88% isolated yield, respectively, although requiring longer reaction times at 60 °C.