(±)-trans-3-Hydroxy-2-(4-methoxyphenyl)-4-oxo-2,3,4,5-tetrahydro-1,5-benzothiazepine 1-Oxide

The title compound, C₁₆H₁₅NO₄S, is a drug intermediate of diltiazem. The molecular packing is stabilized by hydrogen bonding. The seven-membered ring is distorted showing a twist boat conformation. The benzene ring is planar, but the methoxyphenyl ring deviates significantly from planarity. The methoxyphenyl and hydroxy groups are gauche oriented with respect to one another. The methoxyphenyl group is axial and the carbonyl O atom is pseudo-axial to the seven-membered ring.

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