Synthesis of cyanoalkyl indolines through cyanoalkylarylation of N-allyl anilines with alkyl nitriles under metal-free and neutral conditions

An α-C(sp3)−H functionalization of alkyl nitriles under metal-free and neutral conditions is presented. In the presence of di-tert-butyl peroxide (DTBP), N-allyl anilines underwent exo-selective cyanoalkylation/cyclization cascade, providing a direct access to 3-cyanoalkyl indolines. Previously, a transition-metal catalyst and/or a strong base were generally required to activate nitrilic α-C−H bonds. This reaction features a broad substrate scope and low cost, and primary, secondary and tertiary indolin-3-yl nitriles could all be assembled.