A brief overview on recent advances in spiro[chromane-2,4'-piperidine]-4(3H)-one-functionalized compounds in medicinal chemistry research.

The spiro[chromane-2,4'-piperidine]-4(3H)-one is an important pharmacophore. It is a structural component in many drugs, drug candidates (or lead compounds) and various biochemical reagents. This review demonstrated an impressive progress in syntheses of spiro[chromane-2,4'-piperidine]-4(3H)-one-derived compoundsin the recent years and focuses on features of their biological relevance's. The prospects for the development of new biologically active substances containing a spiro[chromane-2,4'-piperidine]-4(3H)-one pharmacophore are analyzed and briefly discussed in terms of its structure, reaction, mechanism, scope and potential utility.

3-Bromo-chroman-4-one.

The heterocyclic ring of the title compound, C9H7BrO2, obtained by bromination of 4-chromanone with copper bromide, adopts a half-chair conformation. The supramol-ecular structure is governed by a weak C-H⋯O hydrogen bond. There is also π-π stacking between symmetry-related benzene rings; the centroid-centroid distance is 3.9464 (18), the perpendicular distance between the rings is 3.4703 (11) and the offset is 1.879 Å.

3-(4-Nitro-benz-yl)-4H-chromen-4-one.

In the title compound, C16H11NO4, the dihedral angle between the ten-membered chromen-4-one ring system (r.m.s. deviation = 0.0095 Å) and the benzene ring is 86.16 (5)°. In the crystal, mol-ecules are linked into a three-dimensional network by weak C-H⋯O hydrogen bonds. The crystal studied was a non-merohedral twin, with the minor twin component refining to 0.093 (1).

(E)-3-(4-Cyclo-hexyl-3-fluoro-benzyl-idene)chroman-4-one.

The title compound, C(22)H(21)FO(2), exhibits substitutional disorder of the F atom and a H atom in the asymmetric unit with different occupancies, the refined F:H ratio being 0.80 (2):0.20 (2). The dihedral angle between the fluorinated benzene ring and the benzene ring of the chromanone system is 37.30°. There are two relatively high residual electron-density peaks associated with the disorder.

Anti-inflammatory activities of selected synthetic homoisoflavanones.

Four homoisoflavanones of the 3-benzylidene-4-chromanone type, some of which were previously isolated from Caesalpinia pulcherrima, were synthesised to determine their anti-inflammatory activity and cytotoxicity. A range of four different homoisoflavanones (compounds 4a-4d) were synthesised from the corresponding substituted phenols. ¹H- and ¹³C-NMR data together with high-resolution mass spectroscopy data were employed to elucidate the structures. Anti-inflammatory activity was determined in mice with acute croton oil-induced auricular dermatitis. In vitro cytotoxicity was tested against a Chinese hamster ovarian cell line using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide (MTT) assay. Compound 4a exhibited a tendency to inhibit oedema in a dose-dependent manner after 3 and 6 h of treatment. Compounds 4b-4d also inhibited oedema, although a clear dose-response relationship was not observed. Compounds 4a-4c were found to be less cytotoxic than compound 4d. Compound 4b was the least cytotoxic. Compounds 4a-4d exhibited anti-inflammatory activity and varying levels of cytotoxicity.

3-(3,4-Dichloro-benzyl-idene)chroman-4-one.

The distinctive feature of the structure of the title compound, C(16)H(10)Cl(2)O(2), is the formation of a zigzag chain along [100] via Cl⋯Cl inter-actions [3.591 (1) and 3.631 (1) Å]. The chroman-one moiety is fused with the benzene ring and adopts a half-chair conformation. The dihedral angle between the benzene ring of the chromanone moiety and the dichlorobenzene plane is 56.14 (8)°.

3-Benzyl-5,7-dimeth-oxy-chroman-4-ol.

In the crystal structure of the title compound, C(18)H(20)O(4), O-H⋯O hydrogen bonds connect the mol-ecules in parallel layers along the b axis.