3-Hydroxy-2-(4-methoxyphenyl)-2,3-dihydro-1,5-benzothiazepin-4(5H)-one, (2S,3S)

Its stereochemistry ((2S,3S) configuration) is crucial because it leads to the biologically active form of the drug. In the synthesis, this compound undergoes acetylation of the hydroxyl group followed by side-chain introduction (typically via esterification with a dimethylaminoethyl group), ultimately forming diltiazem. The controlled formation and preservation of its stereocenters ensure the desired pharmacological activity and selectivity of the final product. (2S,3S)-3-Hydroxy-2-(4-methoxyphenyl)-2,3-dihydro-1,5-benzothiazepin-4(5H)-one is a key chiral intermediate in the synthesis of diltiazem, a calcium channel blocker.