Total Synthesis of (−)-Chanoclavine I and an Oxygen-Substituted Ergoline Derivative

An efficient and direct route to
ergot alkaloid (−)-chanoclavine
I (3) is described using the inexpensive compound (2R)-(+)-phenyloxirane (15) as a chiral pool
in 13 steps with 17% overall yield. Key features of the synthesis
include a palladium-catalyzed intramolecular aminoalkynylation of
terminal olefin and a rhodium-catalyzed intramolecular [3 + 2] annulation.
An oxygen-substituted ergoline derivative (−)-25 was also achieved by using the same strategy.