Synthesis of barettin

The indole alkaloid barettin (with bromine in 6-position), isolated from the marine sponge Geodia Barretti, has been synthesised via a Horner–Wadsworth–Emmons type reaction from 6-bromoindole-3-carboxaldehyde to introduce the dehydro-functionality. Subsequent deprotection and cyclisation afforded the natural product in Z-conformation.