Stereoselective Construction of Spiro-Fused Tricyclic Frameworks by Sequential Reaction of Enynes, Imines, and Diazoalkenes with Rh(I) and Rh(II) Catalysts

Stereoselective construction of spiro-fused
tricyclic compounds
from enynes having a tethered imine with diazoalkenes was achieved
by Rh­(I)- and Rh­(II)-catalyzed sequential reactions. This method consists
of three reactions, i.e., Rh­(I)-catalyzed cyclization of enynes with
a tethered imine, Rh­(II)-catalyzed cyclopropanation with diazoalkenes,
and Cope rearrangement. Notably, the sequential reactions can be operated
in one pot, in which Rh­(I) and Rh­(II) catalysts work in relay without
any serious catalyst deactivation to afford the spirocycles in a stereoselective
manner.