Synthesis of a proposed 1,3,4-trisubstituted isoquinoline

The total synthesis of a proposed 1,3,4-trisubstituted isoquinoline 5 with an unprecedented 6-6-5-5 tetracyclic ring system is described. One of the key steps is an intramolecular aldol reaction with a combination of a Lewis acid (TBDMSOTf) and a mild base (i-Pr2NEt) to construct the central cyclopentane ring.