4-Acetyl-1H-pyrrole-2-carbaldehyde.

The title compound, C(7)H(7)NO(2), was synthesized via a one-pot Vilsmeier-Haack and subsequent Friedel-Crafts reaction. The pyrazole ring makes dihedral angles of 4.50 (9) and 2.06 (8)°, respectively, with the aldehyde and acetyl groups. In the crystal, classical N-H⋯O hydrogen bonds and weak C-H⋯O inter-actions assemble the mol-ecules into a chain along the b axis.

1-(1-Benzyl-1H-benzimidazol-2-yl)ethanone.

In the title compound, C16H14N2O, the benzimidazole ring system is essentially planar. The planes of the benzene rings make a dihedral angle of 85.92 (8)°. In the crystal, neighbouring molecule are connected into paris along the c axis by weak C-H⋯O interactions and the connected pairs are expanded through C-H⋯N hydrogen bonds and C-H⋯π interactions along the b axis.