Seven membered rings via intramolecular Pauson–Khand reactionsElectronic supplementary data (ESI) available: spectroscopic and analytical characterization of compounds 5–8 and 10. See http://www.rsc.org/suppdata/cc/b1/b108134a/
The synthesis of indoles bearing alkenyl and alkynyl moieties in different positions of the nucleus is described. These compounds are used as substrates for the intermolecular Pauson−Khand reaction leading to tetracyclic cyclopentenones with formation of additional five- to seven-membered rings. Products are related to alkaloids such as mitosenes, clausines, ergotamines, or apogeissochizines.