Development of an Alkyne Analogue of the de Mayo Reaction: Synthesis of Medium-Sized Carbacycles and Cyclohepta[b]indoles.

Embedded medium-sized carbacycles and cyclohepta[b]indoles occur frequently as scaffold elements in natural products and bioactive compounds. Described herein is a conceptionally novel photochemically triggered cascade process to these scaffolds. Key to the cascading ring-expansion process is an unprecedented intramolecular alkyne analogue of the de Mayo reaction.