Start with a sulfone: a sulfur doubly bonded to two oxygens (-SO2-) and bearing two carbon substituents.

1. One substituent is a simple methyl group (-CH3) bonded directly to sulfur.

2. The second substituent is a four-carbon saturated chain attached to sulfur. Number this chain from sulfur as C1-C2-C*-C4, where C* (the third carbon from sulfur) carries a side chain:
    - C* is bonded to an oxygen that continues to a carbonyl (-O-C(=O)-), forming an ester linkage.
    - The carbonyl carbon is followed by two methylene units (-CH2-CH2-) that connect to a thiophene ring (five-membered aromatic ring with one sulfur).
    - The attachment on thiophene is at the alpha position.