Alkenes and arenes possessing a bidentate directing group are alkylated with a primary or secondary alkylzinc halide in the presence of an iron/diphosphine catalyst and a dichloroalkane oxidant. Acrylamides, including unsubstituted and monosubstituted ones, react stereoselectively. Under these reaction conditions, beta-hydrogen elimination and homocoupling of the organometallic reagent are largely suppressed. The reaction may proceed through C-H activation catalyzed by an organoiron(III) species.