The core is a benzothiazole ring system,  a five-membered aromatic thiazole ring with S at position 1 and N at position 3, fused to a benzene ring with C-4 and C-5 of thiazole ring.

The C-2 of the thiazole is attached a sp3 carbon bearing
- one hydroxyl group (-OH) and
- one carbonyl group that is further esterified with an ethyl group, i.e., -C(=O)OCH2CH3.