Direct Remote Asymmetric Bisvinylogous 1,4-Additions of Cyclic 2,5‑Dienones to Nitroalkenes

Here we report that cyclic 2,5-dienones
can act as bisvinylogous
precursors through in situ generation of linear trienamine species
with a cinchona-derived primary amine, and exclusively remote ε-regioselective
1,4-additions to nitroalkenes were accomplished in moderate to high
enantioselectivity. Moreover, a diversity of complex spirocyclic frameworks
could be efficiently constructed in an enantioenriched manner from
these multifunctional 1,4-adducts via subsequent vinylogous iminium
and even cascade iminium catalysis of the same amine.