(R)-(+)-Dimeth-yl[4-oxido-2-oxo-1-(1-phenyl-eth-yl)-1,2,5,6-tetra-hydro-pyridin-3-yl]sulfonium.

In the title zwitterionic compound, C(15)H(19)NO(2)S, the six-membered heterocycle adopts a sofa conformation. The negative charge is delocalized along the carbonyl and enolate system on the ring and the positive charge is localized on the S atom. Two inter-molecular C-H⋯O inter-actions help to establish the packing.