(7aS)-(–)-Dimethyl(1-oxido-3-oxo-5,6,7,7a-tetrahydro-3H-pyrrolizin-2-yl)sulfonium

In the zwitterionic title compound, C9H13NO2S, the pyrrolidine heterocycle adopts an envelope conformation (with the C atom in the 7-position as the flap). The negative charge is delocalized over the two carbonyl groups and the C atom connecting them. The positive charge is located on the S atom. Two intermolecular C—H...O interactions are observed. The molecular geometry at the S atom is trigonal pyramidal.