1-[4-(4-Fluoro­phen­yl)-6-methyl-2-sulfanyl­idene-1,2,3,4-tetra­hydro­pyrimidin-5-yl]ethanone

In the title mol­ecule, C₁₃H₁₃FN₂OS, the heterocyclic ring adopts a slightly distorted flattened boat conformation, and the plane through the four coplanar atoms makes a dihedral angle of 87.45 (14)° with the benzene ring. The thione, acetyl and methyl groups lie on the opposite side of the heterocyclic mean plane to the fluorophenyl group, which has an axial orientation. N—H...O, N—H...S, C—H...F and C—H...O inter­molecular hydrogen bonds and a weak C—H...π inter­action involving the benzene ring are found in the crystal structure.

1-[4-(4-Isopropyl­phen­yl)-6-methyl-2-sulfanyl­idene-1,2,3,4-tetra­hydro­pyrimidin-5-yl]ethanone

In the title mol­ecule, C₁₆H₂₀N₂OS, the heterocyclic ring adopts a slightly distorted flattened boat conformation, and the plane through the four coplanar atoms makes a dihedral angle of 86.98 (6)° with the benzene ring. The thione, acetyl and methyl groups lie on the opposite side of the heterocyclic mean plane to the isopropylphenyl group which has an axial orientation. A weak intra­molecular C—H...O hydrogen bond is observed. In the crystal, molecules are linked via N—H...O, N—H...S and C—H...S hydrogen bonds.