With the optimized conditions in hand, we then evaluated the group tolerance of this aryl radical activation strategy (Table ). A broad range of secondary alkyl iodides appended to a variety of rings (cyclobutane, cyclopentane, cyclohexane, piperidine, 1,3-dioxane, azetidine, and azepane) afforded the corresponding CF2H products in good to excellent yields (13 to 24, 50% to 90% yield). Functional groups including acetal, carbamate, ester, and even tertiary amine could be tolerated under the reaction conditions. A high diastereoselectivity was observed for the difluoromethylation of the alkyl iodide derived from menthol (18, d.r. = 16:1), presumably induced by the interaction between the bulky isopropyl group and the copper(II) complex during the radical recombination step. Acyclic secondary alkyl iodides, some of which contained reactive hydrogen atoms that were prone to βhydride elimination reactions, were successfully difluoromethylated (25 to 28, 60 to 77% yield). By contrast, previously reported decarboxylative and deaminative difluoromethylation reactions were incapable of installing CF2H groups at acyclic alkyl sites. Next, the compatibility of primary alkyl iodides has been evaluated. Substrates that contain diverse functional groups, such as silyl ether, sulfonamide, imide, perfluoroalkyl, and the base-labile Fmoc group, were found to give good to excellent yields of the desired products (29 to 35, 56% to 88% yield). Alkyl and aryl bromides were accommodated under the reaction conditions (36 and 37, 67% and 82% yield, respectively), providing potential opportunities for the diversification of the difluoromethylated products. A substrate that contained an aryl iodide moiety could be selectively activated at the C(sp 3 ) site with 1.3 equiv. of diazonium salt being employed (38, 59% yield); the use of more diazonium salts led to the protodeiodination of the aryl iodide group, indicating a competing iodine abstraction from the aryl ring (k = 9 × 10 7 M - 1 s -1 ). Notably, unprotected phenol and aldehyde groups, which were typically problematic in cross-coupling reactions involving reactive organometallic reagents, did not interfere the difluoromethylation reactions (39 and 40, 92 and 91% yield, respectively). An electron-rich aromatic ring, which was prone to arylation with aryl radicals in the Gomberg-Bachmann reaction, was well tolerated (41, 85% yield). Substrates that contained potential nucleophiles, such as unprotected indole and terminal alkyne, which were known to react with alkyl iodides under related conditions , could furnish the desired products in reasonable yields (42 and 43, 49% and 42%, respectively). Difluoromethylation of alkyl iodides that consisted of pharmaceutically relevant heterocycles, including thiophene, oxazole, thiazole, and pyridine, was accomplished in generally good efficiency. (44 to 47, 46% to 69% yield). Finally, the scalability of this protocol has been demonstrated with the synthesis of compound 32 in a 5 mmol scale (65% yield). Reactions were run with 0.25 mmol of alkyl iodides, 0.625 mmol of 4a (2.5 equiv.), 0.375 mmol of 1 (1.5 equiv.), L1 (20 mol %) and Cu(OTf)2 (20 mol %) in 1.5 mL of DMSO at r.t. under Ar. Isolated yields were reported. b Yield determined by F NMR due to the volatility of the product. c Yield and diastereoselectivity determined by F NMR of the crude reaction mixture. Isolated yield of the major isomer shown in parenthesis. Reactions were run with 0.25 mmol of alkyl iodides, 0.625 mmol of diazonium salt (2.5 equiv.), 0.375 mmol of 1 (1.5 equiv.), L1 (20 mol %) and Cu(OTf)2 (20 mol %) in 1.5 mL of DMSO at r.t. under Ar. Isolated yields were reporte