Methyl 12-Acetyl-9-methyl-11-thioxo-8-oxa-10,12-diazatricyclo[7.3.1.0^2,7]trideca-2,4,6-triene-13-carboxylate

The title compound, C₁₅H₁₆N₂O₄S, represents a conformationally restricted dihydropyrimidine analogue of 1,4-dihydropyridine-type calcium antagonists and was selected for a crystal structure determination in order to clarify some aspects of structure-activity relationships. The carbonyl function of the acetyl group is oriented cis with respect to the C2-N3 bond, presumably to avoid repulsive interaction between the negatively charged carbonyl O and thione S atoms.

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