We
herein report regiodivergent ligand-controlled palladium-catalyzed
asymmetric cycloaddition reactions between spirovinylcyclopropyl oxindoles
and o-quinone methides. Specifically, by using the
chiral P,P-ligand Segphos (L5), we obtained various spirooxindole-3,4-benzo[b]oxepanes in moderate to good yields with excellent enantioselectivities
via [4+3] cycloaddition reactions. In contrast, reactions involving
Trost’s ligand (L7) showed different regio- and
stereoselectivities, affording bispirooxindole heterocyclic compounds
in good yields via [2+3] cycloaddition reactions.
We have developed a synthetic strategy for Et 3 N-promoted [5 + 3] cycloaddition reactions between acetoxypyranones and azomethine imines to access functionalized azabicyclo[3.3.1]alkenones with three tertiary stereocenters (31 examples, 36% to 87% yield, 5.5:1 to > 20:1 dr). The method was scalable, and the products could be transformed to various eight-membered-ring bridged heterocyclic molecules.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.