Theoretical study on β-H elimination in Heck reactions of heterocyclic substrates

► Syn-βH elimination in traditional Heck mechanism could not occur for heterocycles. ► Base-assisted anti-βH elimination is the most kinetically favored for heterocycles. ► Isomerization and synβH elimination and αH elimination and 1,2H shift were not favored. ► Carbonate as the base is more beneficial for the anti-βH elimination than the amine.