Reaction Scheme
aryl halide + alkene -> substituted alkenePd catalyst, base, heat; often gives E-alkene products.
Primary reaction SMILES: Brc1ccccc1.C=CC(=O)OC>>COC(=O)C=Cc1ccccc1
Organic reaction
Heck Reaction
The Heck reaction forms substituted alkenes by palladium-catalyzed coupling of aryl or vinyl halides with alkenes.
Two Common Examples
Bromobenzene + methyl acrylate
Forms cinnamate-type ester products.
Aryl iodide + styrene
Forms stilbene derivatives under Pd/base conditions.
MolDraw Use
Use MolDraw to communicate regioselectivity, alkene geometry, catalysts, and product structures.
How It Works
The Heck (Mizoroki–Heck) reaction follows a Pd(0)/Pd(II) catalytic cycle. Pd(0) undergoes oxidative addition into the aryl–halide bond. The alkene coordinates and inserts into the Pd–aryl bond (migratory insertion, syn addition). β-Hydride elimination then releases the substituted alkene, and the base removes HX from the palladium hydride to regenerate Pd(0).
Conditions and Scope
- Halide reactivity generally follows I > Br ≫ Cl; aryl triflates also work.
- Electron-poor alkenes such as acrylates and styrene react well, and the aryl group usually adds to the less substituted alkene carbon.
- Products are typically the E (trans) alkene.
- Common catalysts include Pd(OAc)2 with phosphine ligands; bases include triethylamine or carbonates.
FAQ
How is it different from Suzuki coupling? Heck couples an aryl halide with an alkene C–H, with no organometallic partner, while Suzuki coupling uses a boronic acid. How do I show the catalyst? Write "Pd(OAc)2 (cat.), PPh3, Et3N, heat" above and below the arrow, or draw the catalytic cycle as a loop of arrows for teaching.