Selective photochemical monoalkylation of active methylene compounds by alkenes. A green pathway for carbon–carbon bond formation

A novel photochemical method for selective α-monoalkylation of active methylene compounds has been developed. Aryl substituted alkenes and an aliphatic diene can be used as alkyl sources for these reactions, which proceed via polycyanoarene sensitized, photoinduced electron transfer pathways that are promoted using very mild conditions (ambient temperature, without noble metals and halogens, and with weak bases such as alkali metal carbonate). The reactions that comprise the new synthetic methods developed in this effort are both safe and environmentally friendly. Especially noteworthy is the fact that photochemical alkylation reactions of β-ketoesters (e.g., acetoacetic and malonic esters) can be used in the place of conventional strong base promoted processes.