High Yield Endoselective Heterocycloadditions involving Benzylidenepyruvic Esters as the Heterodiene and an Alkoxystyrene as the Dienophile

Article abstract of DOI:10.1016/S0040-4039(00)78452-8

The benzylidenepyruvic esters 6, 10a-d and 11 smoothly reacted with the alkoxystyrenes 12 and 13 in refluxing hexane or toluene and in the presence of catalytic amounts of Eu(fod)3, thus selectively leading to the endo adducts 14-21 in high yields.This represents the first examples of an efficient heterocycloaddition of styrene derivatives without using the high pressure technique.The above adducts are potential intermediates for sugiresinol 7 and related tetrahydropyran neolignans.