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A new application of NBS, which results in the oxidative coupling of β‐keto esters to selectively form C‐C single and C˭C double bonds, can be controlled by the amount of NBS and t‐BuOK employed. This methodology adds a new entry to C‐C single and C˭C double‐bond formation between active methylene groups under mild conditions with high selectivity.

In the title compound, C25H24O9, the substituted benzene rings are twisted away from the furan ring. The dihedral angle between the two benzene rings is 52.1 (1)°. In the crystal structure, the mol­ecules exist as hydrogen-bonded dimers, the mol­ecules being connected through very weak C—H⋯O hydrogen bonds.

In the title compound, C22H20O5, the substituted benzene rings are twisted away from the furan ring, making dihedral angles of 54.91 (14) and 20.96 (15)° with the furan ring. The dihedral angle between the two benzene rings is 46.89 (13)°. One ethyl group of one ethoxycarbonyl unit is disordered over two sets of sites with occupancies of 0.56 (12) and 0.44 (12). In the crystal, weak intramolecular C—H...O hydrogen bonds link the molecules into chains along the c axis.

A new application of NBS, which results in the oxidative coupling of β‐keto esters to selectively form C‐C single and C˭C double bonds, can be controlled by the amount of NBS and t‐BuOK employed. This methodology adds a new entry to C‐C single and C˭C double‐bond formation between active methylene groups under mild conditions with high selectivity.

The title compound, C25H20N4·4H2O, crystallizes with the organic molecule lying on a twofold rotation axis through the methylene bridge C atom; there are also two water molecules in the asymmetric unit. The crystal structure is stabilized by C—H...O, O—H...O and O—H...N hydrogen bonds, linking the water molecules to each other and to the pyridine N atom.

In the title compound, C24H20O9, the dihedral angle between the two benzene rings is 2.32 (13)°. The mol­ecular conformation is stabilized by some weak C—H⋯O inter­actions.

In the title compound, C2H4N3+·C6H2N3O7−, the dihedral angle between the triazolium ring and the benzene ring of the picrate anion is 73.5 (2)°.

The title compound, C24H18Br2N4O2·H2O, forms a supramolecular structure via N—H...O, O—H...O and C—H...O hydrogen bonds. In the crystal structure, the water molecule serves as a bifurcated hydrogen-bond acceptor and as a hydrogen-bond donor.

The title compound, C26H30O10, is the meso isomer of a 2,3-disubstituted succinic acid derivative and has inversion symmetry. The crystal structure is stabilized by inter­molecular C—H⋯π and π–π stacking inter­actions.

The mol­ecule of the title compound, C30H28N6O6, a glycoluril derivative, lies on a twofold rotation axis with two ethyl acetate groups bonded to the convex face of the glycoluril system. The dihedral angle between the imidazolone rings is 73.12 (3)°. Two symmetry-equivalent six-membered triazine rings are fused to the glycouril unit to form rigid side walls of a mol­ecular clip. The crystal structure is stabilized by weak inter­molecular C—H⋯O hydrogen bonds. The ethyl ester group is disordered over two sites of occupancy 0.539 (7) and 0.461 (7).

The title compound, C25H20N6O3·CHCl3, a rigid glycoluril derivative, is an inter­mediate for the synthesis of mol­ecular tweezers. The crystal structure is stabilized by inter­molecular C—H⋯O and N—H⋯O hydrogen bonds. The chloro­form solvent mol­ecule is disordered over two positions; the site occupancy factors are ca 0.89 and 0.11.