Cyanomethylation and Cyclization of Aryl Alkynoates with Acetonitrile under Transition-Metal-Free Conditions: Synthesis of 3‑Cyanomethylated Coumarins

Cyanomethylated
coumarins were synthesized via cyanomethylation
and cyclization of aryl alkynoates using cheap and available reagent
acetonitrile as the cyanomethyl source in the presence of TBPB (tert-butyl peroxybenzoate) under transition-metal-free conditions.
For the substrates with various substituents on benzene ring, the
reaction proceeded smoothly to give the corresponding products in
moderate to good yields. The resulting products could be simply converted
into some other related coumarin derivatives.