2-[7-(3,5-Dibromo-2-hy-droxy-phen-yl)-6-eth-oxy-carbonyl-2-oxo-5H-2,3,6,7-tetra-hydro-thio-pyrano[2,3-d][1,3]thia-zol-6-yl]acetic acid ethanol monosolvate.

The title compound, C(17)H(15)Br(2)NO(6)S(2)·C(2)H(5)OH, is the esterification reaction product of 2-(8,10-dibromo-2,6-dioxo-3,5,5a,11b-tetra-hydro-2H,6H-chromeno[4',3':4,5]thio-pyrano[2,3-d]thia-zol-5a-yl)acetic acid. Cleavage of the lactone ring and formation of eth-oxy-carbonyl and hy-droxy groups from its structural elements were observed. On the other hand, the carb-oxy-methyl group was not esterified. The H atom and carb-oxy-methyl group, both at stereogenic centres, show a cis conformation. The six-membered dihydro-thio-pyran ring adopts a half-chair conformation. All NH and OH groups participate in the three-dimensional hydrogen-bond network, which is additionally strengthened by C-H⋯O and C-H⋯S inter-actions. Intramolecular O-H⋯Br and C-H⋯O interactions also occur.