Novel stereoselective syntheses of highly functionalized benzannulated pyrrolizidines and indolizidines by samarium diiodide induced cyclizations of indole derivatives.

[reaction: see text] Suitably substituted heteroaromatic compounds such as indole and pyrrole derivatives are excellent acceptor units for intramolecular couplings of samarium ketyls. They furnish highly functionalized indole derivatives with very good diastereoselectivities additionally. Intermediate samarium enolates can be trapped by electrophiles, allowing efficient tandem reactions.