Highly Regioselective Aromatic C–H Allylation of N-(Arylmethyl)sulfonimides with Allyl Grignard Reagents Involving Benzylic C–N Cleavage

A new pair of reaction partners has been established for the aromatic C–H functionalization of benzyl electrophiles with nucleophiles via palladium-catalyzed benzylic C–N cleavage. A range of N-(1-naphthylmethyl)­sulfonimides, N-(2-thienylmethyl)­sulfonimides, and N-(2-furanylmethyl)­sulfonimides smoothly underwent palladium-catalyzed aromatic C–H allylation with allyl Grignard reagents at room temperature, delivering structurally diverse substituted 1-allylnaphthalenes and 2-allylheteroarenes in moderate to excellent yields with extremely high regioselectivities. Replacing the N-(arylmethyl)­sulfonimide with an (arylmethyl)­ammonium salt, an arylmethyl chloride, or an arylmethyl phosphate as the benzyl electrophile leads to a dramatic erosion of the regioselectivity.