Switching Chemoselectivity Based on the Ring Size: How to Make Ring-Fused Indoles Using Transition-Metal-Mediated Cross-Coupling

Pyrroloazocine indole alkaloids consisting of eight-membered azacycle fused to pyrrole and indole units exhibit intriguing pharmacological functions but still pose a synthetic challenge. Here, we report an alternative synthetic strategy for the pyrroloazocine indole core from two key steps: (i) regioselective Fischer indolization and (ii) transition-metal-mediated C–N cross-coupling reaction of N-Boc aryl hydrazine with azacyclic vinyl triflate....