Iron-Catalyzed Directed C(sp²)–H and C(sp³)–H Functionalization with Trimethylaluminum

Conversion of a C­(sp²)–H or C­(sp³)–H bond to the corresponding C–Me bond can be achieved by using AlMe₃ or its air-stable diamine complex in the presence of catalytic amounts of an inorganic iron­(III) salt and a diphosphine along with 2,3-dichlorobutane as a stoichiometric oxidant. The reaction is applicable to a variety of amide substrates bearing a picolinoyl or 8-aminoquinolyl directing group, enabling methylation of a variety of (hetero)­aryl, alkenyl, and alkyl amides. The use of the mild aluminum reagent prevents undesired reduction of iron and allows the reaction to proceed with catalyst turnover numbers as high as 6500.