toward the assembly of the azaspirobicyclic and azaspirotricyclic
cores,4 only three total syntheses of 15-7 and two
total syntheses of 2 have been reported;7,8 there have been
two formal syntheses of 1 and 2.
9,10
Our approach to 1 and 2 was guided by a longstanding
interest in developing new applications of olefin metathesis
for the synthesis of complex natural products, particularly
alkaloids.11,12 We thus envisioned a unified strategy for the
preparation of both of these alkaloids that would feature
chemoselective cross metathesis reactions involving the key
intermediate 10 (Scheme 1).