Concise and scalable formal syntheses of (−)-quinocarcinamide
and (−)-quinocarcin have been achieved in 9 steps with 9% overall
yield from simple commercially available chemicals. The synthetic
strategy features an ortho-regioselective Pictet–Spengler
cyclization for the construction of the tetrahydroisoquinoline skeleton,
a stereoselective formal intramolecular [3 + 2] cross cycloaddition
of cyclopropane 1,1-diester with an imine for the construction of
the 3,8-diazabicyclo[3.2.1]octane skeleton.