Substituted heterobiaryls constitute privileged scaffolds of compounds with activities of relevance to various research areas, ranging from medicinal chemistry and catalysis to material sciences. [1][2][3][4] Their regioselective syntheses rely strongly on transition-metal-catalyzed cross-coupling reactions, which have matured to being indispensable tools in modern organic syntheses. [3,4] Since organomagnesium reagents are more readily available than are alternative organometallic nucleophiles, [5,6] catalytic cross-couplings of Grignard reagents have proven particularly useful for streamlining heterobiaryl synthesis. [7] Therefore, catalysts derived from various transition metals, such as nickel, [8,9] palladium, [10] iron, [11,12] cobalt, [13][14][15] or manganese, [16] were developed for Kumada-Corriu-type [17,18] coupling reactions. [3,4,19] While this research significantly expanded the pool of viable electrophiles, cross-coupling reactions of electron-deficient N-heterocyclic nucleophiles continue to be challenging because of their reduced nucleophilicities. Hence, a generally applicable protocol for metal-catalyzed arylations of less nucleophilic 2-azine Grignard [20] reagents has, to the best of our knowledge, proven elusive. [2,21,22] As part of our program directed towards the use of air-stable secondary phosphine oxides (SPO) as preligands in transition-metal catalysis, [23,24] we noted that efficient cross-couplings with 2-pyridyl organomagnesium compounds could be accomplished, provided that palladium catalysts derived from air-and moisturestable SPOs [23] were employed as preligands. Herein, we report on these findings, which highlight the unique reactivity profile of SPO preligands.