Regioselective Synthesis of 1-Sulfanyl- and 1-Selanylindolizines.

We describe herein a new approach to prepare unprecedented bioactive indolizine motifs decorated with organosulfur and organoselenium groups. A total of 12 1-sulfanylindolizines and 2 1-selanylindolizines were prepared in excellent yields by an intramolecular annulation of easily prepared chalcogen-containing pyridinium salts. The reaction is fast (1 h at 70 °C or 5 min under sonication) and transition-metal-free, using glycerol as a green solvent.