2-[7-(3,5-Dibromo-2-hydroxyphenyl)-6-ethoxycarbonyl-2-oxo-5 H -2,3,6,7-tetrahydrothiopyrano[2,3- d ][1,3]thiazol-6-yl]acetic acid ethanol monosolvate

The title compound, C17H15Br2NO6S2·C2H5OH, is the esterification reaction product of 2-(8,10-dibromo-2,6-dioxo-3,5,5a,11b-tetrahydro-2H,6H-chromeno[4′,3′:4,5]thiopyrano[2,3-d]thiazol-5a-yl)acetic acid. Cleavage of the lactone ring and formation of ethoxycarbonyl and hydroxy groups from its structural elements were observed. On the other hand, the carboxymethyl group was not esterified. The H atom and carboxymethyl group, both at stereogenic centres, show a cis conformation. The six-membered dihydrothiopyran 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 interactions. Intramolecular O—H...Br and C—H...O interactions also occur.