Asymmetric (5 + 3) Annulation of Donor–Acceptor Cyclopropanes with Imidazolidines: Access to Saturated 1,4-Diazocanes

Saturated 1,4-diazocanes are highly important for medicinal
chemistry
and drug discovery, but their syntheses are often tedious. Herein,
we report a copper-catalyzed (5 + 3) annulation of donor–acceptor
cyclopropanes with imidazolidines, thereby providing a straightforward
method to access a library of saturated 1,4-diazocanes in moderate
to excellent yields under mild reaction conditions. More importantly,
the asymmetric version of this (5 + 3) annulation leading to optically
active saturated 1,4-diazocanes is achieved by two strategies: (i)
chirality transfer and (ii) dynamic kinetic asymmetric transformation
by employing copper triflate with an SaBOX ligand. In addition, the
analogous (6 + 3) annulation of donor–acceptor cyclopropanes
with hexahydropyrimidines is also realized.