Intramolecular Aminocyanation of Alkenes by NCN Bond Cleavage

A metal‐free, Lewis acid promoted intramolecular aminocyanation of alkenes was developed. B(C6F5)3 activates N‐sulfonyl cyanamides, thus leading to a formal cleavage of the NCN bonds in conjunction with vicinal addition of sulfonamide and nitrile groups across an alkene. This method enables atom‐economical access to indolines and tetrahydroquinolines in excellent yields, and provides a complementary strategy for regioselective alkene difunctionalizations with sulfonamide and nitrile groups. Labeling experiments with 13C suggest a fully intramolecular cyclization pattern due to the lack of label scrambling in double crossover experiments. Catalysis with Lewis acid is realized and the reaction can be conducted under air. Break free: A Lewis acid promoted intramolecular aminocyanation of alkenes is described. Activation of N‐sulfonyl cyanamides by B(C6F5)3 leads to cleavage of the NCN bond in conjunction with vicinal addition of sulfonamide and nitrile groups across an alkene. This method enables rapid and atom‐economical access to heterocycles in excellent yields. Mechanistic studies indicate that this transformation proceeds without dissociation of the nitrile.