Directed C–H functionalization is a powerful means to functionalize otherwise unreactive C‒H bonds, for which aminoquinoline amides provide a powerful and frequently used directing group. Saturated N-heterocycles are crucial motifs in medicinal chemistry. However, the C–H functionalization of N-heterocycles has posed considerable chal-lenges, often giving incomplete conversions. On unsymmetrical substrates, poorly understood regio- and stereoselectivity considerations have prevented more forcing conditions and further limited yields. Here we present a combined experimental and computational study on the regio- and stereoselective C4 arylation of pyrrolidines and piperidines with C3 aminoquinoline amide directing groups. Detailed mechanistic experiments are presented including deuteration, kinetics investigations, and isolation of palladacycles. The palladacycle formation is reversible and proceeds preferentially at C4, though activation of both C–H bonds at C4, cis and trans to the directing group, occurs equally. The cis-selectivity results from strain in the trans-palladacycle (ΔΔGtrans-cis ~6 kcal∙mol–1), that is retained in subsequent transition states. Hence, the oxidative addition step is stereodetermining. However, the turnover-limiting step for the catalytic cycle is reductive elimination, and reduced rates and yields were observed with electron poor aryl iodides. Importantly, kinetics experiments reveal a rapid loss of active Pd catalyst, likely due to the build-up of iodide, and a role for K2CO3/PivOH in catalyst turnover. Finally, we present the discovery of an improved 4-dimethylamine-8-aminoquinoline directing group (DMAQ). This removable auxiliary achieves >2x rate acceleration, generally im-proved yields, as well as improved cis-selectivity, by promoting reductive elimination. A broad reaction scope of aryl iodides is demonstrated, including the late-stage functionalization of drug compounds which is enabled by the use of only one equivalent of functionalized iodides.