We developed a novel Pd-catalyzed [4 + 4] cycloaddition of
benzofuran-derived azadienes with homo-TMM all-carbon 1,4-dipoles in
situ generated from α-allyl malonate derivatives, affording an
array of benzofuro[3,2-b]azocines with good to excellent
yields (up to 96%) and exclusive regioselectivities. This methodology
featured mild reaction conditions and good functional group tolerance.
The synthetic utility was demonstrated by a gram-scale reaction.
Furthermore, the catalytic asymmetric [4 + 4] cycloaddition version
has also been explored. |