1. Begin with a saturated 5-membered heteroring (pyrazolidine).  Number the ring so that the two adjacent nitrogens are positions 1 and 2; positions 3, 4 and 5 are the successive carbons that complete the ring.

2. Substituents on the pyrazolidine:
   - Position 3 carries an exocyclic carbon that is double-bonded to it (C3=(C-alpha), no E/Z configured).  
     - Carbon C-alpha is part of a second 5-membered ring composed of the sequence (C-alpha)-S-(C-beta)=(C-gamma)-(C-detla)- (back to C-alpha).   
     - Only C-beta and C-gamma are connected by a double bond; all other bonds in the ring are single.
     - Carbon C-detla double bonds to an external oxygen, forming a carbonyl ((C-detla)=O).

   - Position 5 of the pyrazolidine is bonded to a phenyl ring (unsubstituted benzene) via a single bond.