Synthesis and Crystal Structure of 2-Amino-4-(3-isobutyl-1-phenyl-1 H -Pyrazol-4-yl)-7,7-dimethyl-5-oxo-5,6,7,8-tetrahydro-4 H -Chromene-3-carbonitrile

The title compound, C 25 H 28 N 4 O 2 , crystallizes in space group P 1 with Z = 4. The two independent molecules are related by the approximate translation ( x + 1, y + 1, z ), but differ in the orientation of the phenyl substituent. Crystals are non-merohedrally twinned by a 180° rotation about c *. In the modified chromene ring systems, the two formal double bonds are the shortest C—C bonds. The oxo ring displays a flattened boat conformation, whereas the other ring is approximately a flattened envelope, with the CMe 2 C atom out of the plane. The molecules are connected by classical N—H...N pyrazole hydrogen bonds to form a ribbon of alternating independent molecules parallel to [110]. The ribbons are joined by weak C pyrazole —H...N nitrile hydrogen bonds to form a layer structure parallel to the ab plane in the region z ≃ 3/4.