Illustrated Glossary of Organic Chemistry

Heck reaction: A substitution reaction involving an aryl, benzylic, or vinylic halide or triflate and an alkene having at least one vinylic hydrogen, resulting in substitution of the vinylic hydrogen for the group that has the halide or triflate. Requires a Pd⁰ catalyst and a base.

In this example Heck reaction, vinyl iodide reacts with methyl methacrylate (an α,β-unsaturated ester) in the presence of Pd(PPh₃)₄ (a Pd⁰ catalyst) and K₂CO₃ (a mild base). The product is a 1,3-diene.