4-[4-(Cyclopentyloxy)-2-quinolinyl]-1,2-benzenediol
[CAS 1353224-53-9]

Identification

• Classification: Pharmaceutical intermediate >> Heterocyclic compound intermediate >> Quinoline compound
• Name: 4-[4-(Cyclopentyloxy)-2-quinolinyl]-1,2-benzenediol
• Synonyms: CMS-121
• Molecular Formula: C20H19NO3
• Molecular Weight: 321.37
• CAS Registry Number: 1353224-53-9
• SMILES: C1CCC(C1)OC2=CC(=NC3=CC=CC=C32)C4=CC(=C(C=C4)O)O

Properties

• Density: 1.3±0.1 g/cm³ Calc.^*
• Boiling point: 511.0±50.0 °C 760 mmHg (Calc.)^*
• Flash point: 262.9±30.1 °C (Calc.)^*
• Index of refraction: 1.68 (Calc.)^*

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H302-H315-H319-H335
• Safety Statements: P261-P264-P270-P271-P280-P301+P312-P302+P352-P304+P340-P305+P351+P338-P330-P332+P313-P337+P313-P362-P403+P233-P405-P501

Discovery and Applications

4-[4-(Cyclopentyloxy)-2-quinolinyl]-1,2-benzenediol is a substituted quinoline derivative containing several chemically significant structural motifs: a quinoline heteroaromatic core, a cyclopentyloxy substituent, and a catechol (1,2-benzenediol) moiety. Based on its structure, it can be classified as a multifunctional aromatic heterocyclic compound with both hydrophobic and strongly polar regions.

The central quinoline system is a fused bicyclic heteroaromatic ring composed of a benzene ring joined to a pyridine ring. Quinoline frameworks are electron-deficient relative to benzene because of the ring nitrogen atom, and they frequently serve as scaffolds in heterocyclic and medicinal chemistry. The aromaticity of the fused ring contributes structural rigidity and extended π-electron delocalization.

At the 4-position of the quinoline ring, a cyclopentyloxy group (–O–cyclopentyl) is attached. This substituent introduces an ether linkage and a saturated cycloaliphatic ring. The ether oxygen can function as a hydrogen-bond acceptor, while the cyclopentyl ring contributes hydrophobic character and conformational flexibility. Cyclopentane itself is nonplanar and typically adopts puckered conformations to minimize strain.

The molecule also contains a 1,2-benzenediol unit, commonly called a catechol moiety. The two adjacent hydroxyl groups are among the most chemically significant features of the structure. Catechol systems readily participate in hydrogen bonding and can undergo oxidation to corresponding quinone species under appropriate conditions. This redox behavior often strongly influences the chemical properties of catechol-containing molecules.

Electronically, the catechol ring is electron-rich because the hydroxyl groups donate electron density through resonance. In contrast, the quinoline ring is relatively electron-deficient. The presence of these electronically distinct regions creates a molecule with nonuniform charge distribution and potentially complex intermolecular interaction behavior.

From a physicochemical standpoint, the molecule would be expected to display mixed polarity. The aromatic and cyclopentyl portions contribute hydrophobic character, whereas the hydroxyl groups and ether oxygen increase polarity and hydrogen-bonding capability. Such structural balance often influences solubility and molecular interactions in organic and biological environments.

The most chemically reactive sites in the molecule are likely to be the catechol hydroxyl groups and, under certain conditions, the aromatic system adjacent to these substituents. The hydroxyl groups can undergo reactions such as esterification, etherification, oxidation, and metal coordination. The quinoline nitrogen may also participate in protonation or coordination chemistry.

Without verified experimental literature specific to this compound, further claims regarding biological activity, pharmacology, or specific applications should not be made. From the established structure alone, it can be described reliably as a substituted quinoline–catechol derivative with a combination of aromatic, ether, and diol functionalities that provide diverse chemical behavior and synthetic utility.

References

2011. Chemical Modification of the Multitarget Neuroprotective Compound Fisetin. Journal of Medicinal Chemistry.
DOI: 10.1021/jm2012563