Palladium-catalyzed [4 + 4] cycloaddition of homo-TMM all-carbon
1,4-dipole precursors for the construction of
benzofu-ro[3,2-b]azocines
Abstract
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.