The Construction of Chiral Fused Azabicycles Using a Pd-Catalyzed Allylic Substitution Cascade and Asymmetric Desymmetrization Strategy

A highly
enantioselective Pd-catalyzed asymmetric allylic substitution
cascade of cyclic N-sulfonylimines with an accompanying
asymmetric desymmetrization has been developed for the construction
of fused tetrahydroindole derivatives bearing two chiral centers.
Mechanistic studies confirmed that the cascade reaction proceeds by
initial allylic alkylation and subsequent allylic amination. The first
alkylation is a chirality-control step and represents an asymmetric
desymmetrization of cis-cyclic allyl diacetates.
The reaction has been performed on a gram scale, and the desired products
can take part in several transformations.