The chromium(III) sensitizer [Cr(ddpd)2]3+ (ddpd=N,N′‐dimethyl‐N,N′‐dipyridine‐2‐ylpyridine‐2,6‐diamine), based on an earth‐abundant metal centre, possesses a unique excited‐state potential‐energy landscape. The very large energy gap between the redox‐active and substitutionally labile 4T2 state and the long‐lived low‐energy 2E spin‐flip state enables a selective, efficient sensitization of triplet dioxygen to give singlet dioxygen. Ultrafast intersystem crossing after the Franck Condon point from the 4T2 to the 2E excited state within 3.5 ps precludes intermolecular electron‐transfer pathways from the ultrashort‐lived excited 4T2 state. This specific excited‐state reactivity enables a selective visible‐light‐induced C−H bond activation of tertiary amines with 1O2 and subsequent trapping with cyanide to yield α‐aminonitriles in good to excellent yields.

This review focuses on alternative cyanide sources and cyanating agents which are less hazardous than HCN or its salts.

Levetiracetam is an active pharmaceutical ingredient widely used to treat epilepsy.