Terminal Heck vinylations of chelating vinyl ethers

Terminal chelation-controlled Heck vinylations of electron-rich amino-functionalized vinyl ethers were performed with high regioselectivity furnishing moderate to good isolated yields of the corresponding 1-alkoxy-1,3-butadienes. DFT calculations support an amine-palladium(II) coordination strength reactivity/selectivity rationale, where the dimethylamino group was the preferred metal presenting functionality. Controlled microwave heating effectively accelerated these palladium-catalyzed reactions and full conversion could be achieved within 30 minutes. Subsequent Diels-Alder reactions with dimethyl acetylenedicarboxylate under microwave irradiation resulted exclusively in partly aromatized bi- and tricyclic compounds by elimination of the aminoalkoxy group. Thus, the selected dimethylamino auxiliary both controlled the regiochemistry in the palladium-catalyzed vinylation and was easily displaced in the aromatization process.