The alkyl electrophile scope was examined using the same optimization strategy that was utilized for exploring the scope of the aryl electrophile. Primary benzyl chlorides (vide supra) as well as unactivated primary alkyl iodides (vide supra) and bromides (4a-4w) can be readily coupled under our reaction conditions. However, Co Pc activates alkyl substrates via an SN2 mechanism, which differentiates it from conventional CEC systems that activate alkyl substrates through a radical pathway. One advantage of this difference is that our system can couple primary alkyl mesylates, such as 3-phenylpropyl methanesulfonate (4x), with methyl 4bromobenzoate in high yield. This result is notable because alkyl mesylates can be readily generated in situ from the corresponding alcohols, which are abundant and diverse building blocks that are commonly used in pharmaceutical research. In contrast, while substrates with some steric bulk at the α-carbon of alkyl bromides, such as (bromomethyl)cyclohexane (4y), can be coupled with methyl 4-bromobenzoate, no product is generated when either neopentyl bromide or iodide are used as substrates (see SI). Similarly, branched secondary alkyl halides such as iodides (4z) and benzyl chlorides (4aa) can be coupled in moderate yields, but branched secondary alkyl bromides and iodocyclohexane are unreactive (see SI). In a subsequent section we explore the types of functionalized alkyl bromides and iodides and benzyl chlorides that are compatible with our system.