5-Hydroxy-3,4-dihydro-2(1H)-quinolinone
[CAS# 30389-33-4]

Identification

• Classification: Pharmaceutical intermediate >> Heterocyclic compound intermediate >> Pyrimidine compound >> Ketones
• Name: 5-Hydroxy-3,4-dihydro-2(1H)-quinolinone
• Synonyms: 5-Hydroxy-3,4-dihydrocarbostyril; 5-Hydroxy-3,4-dihydrocarbostyryl
• Molecular Formula: C₉H₉NO₂
• Molecular Weight: 163.17
• CAS Registry Number: 30389-33-4
• EC Number: 608-474-6
• SMILES: C1CC(=O)NC2=C1C(=CC=C2)O

Properties

• Solubility: Sparingly soluble (21 g/L) (25 °C), Calc.^*
• Density: 1.282±0.06 g/cm³ (20 °C 760 Torr), Calc.^*

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software V11.02 (©1994-2014 ACD/Labs)

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H302-H312-H315-H319-H332-H335
• Safety Statements: P261-P264-P264+P265-P270-P271-P280-P301+P317-P302+P352-P304+P340-P305+P351+P338-P317-P319-P321-P330-P332+P317-P337+P317-P362+P364-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	4	H332
Skin irritation	Skin Irrit.	2	H315
Acute toxicity	Acute Tox.	4	H312
Acute toxicity	Acute Tox.	4	H302
Specific target organ toxicity - single exposure	STOT SE	3	H335
Eye irritation	Eye Irrit.	2A	H319
Eye irritation	Eye Irrit.	2	H319

Discovery and Applications

5-Hydroxy-3,4-dihydro-2(1H)-quinolinone is an organic compound belonging to the class of quinolinone derivatives, characterized by a partially saturated quinoline core structure. The molecular framework consists of a quinolinone skeleton with a hydroxyl group substituted at the 5-position and saturation at the 3 and 4 positions, resulting in a 3,4-dihydroquinolinone ring system. The compound contains a lactam (cyclic amide) functionality at the 2-position, giving rise to the 2(1H)-quinolinone tautomeric form, where the hydrogen is attached to the nitrogen atom in the ring.

Quinolinone derivatives such as 5-hydroxy-3,4-dihydro-2(1H)-quinolinone have been studied extensively for their potential biological and pharmaceutical properties. The lactam group contributes to hydrogen bonding and increases the chemical stability of the molecule, while the hydroxy substituent can modulate both electronic and steric properties, influencing interactions with biological targets.

The compound is typically synthesized via methods involving cyclization of suitable amino-ketone precursors or through modifications of quinoline or quinolinone frameworks. The partial saturation at the 3,4-positions can be introduced through selective reduction reactions or by using specific synthetic routes that favor the dihydro form over the fully aromatic quinolinone.

Applications of 5-hydroxy-3,4-dihydro-2(1H)-quinolinone are primarily in medicinal chemistry research, where it serves as a structural motif or intermediate for the development of pharmacologically active agents. Quinolinone derivatives have been investigated for a variety of biological activities, including antimicrobial, anti-inflammatory, and anticancer properties. The presence of the hydroxy group and the dihydro ring saturation can enhance binding affinity to enzyme active sites or receptor proteins.

In synthetic organic chemistry, this compound may be used as a building block for the synthesis of more complex heterocyclic molecules. Its functional groups allow for further derivatization via reactions such as alkylation, acylation, or oxidation, enabling the exploration of structure-activity relationships in drug design.

From a physicochemical perspective, 5-hydroxy-3,4-dihydro-2(1H)-quinolinone is expected to be a crystalline solid with moderate polarity due to the lactam and hydroxyl groups. It is soluble in polar organic solvents and may exhibit hydrogen bonding in the solid state, which can affect its melting point and crystallinity.

Analytical techniques such as nuclear magnetic resonance (NMR) spectroscopy, infrared (IR) spectroscopy, and mass spectrometry are employed to confirm the structure and purity of the compound. The NMR spectrum typically shows signals corresponding to the protons on the saturated carbons at positions 3 and 4, as well as the aromatic protons and the hydroxyl proton. Infrared spectra display characteristic absorption bands for the lactam carbonyl and hydroxyl groups.

In conclusion, 5-hydroxy-3,4-dihydro-2(1H)-quinolinone is a partially saturated quinolinone derivative with a hydroxyl substitution, serving as a valuable compound in pharmaceutical research and organic synthesis. Its structural features provide opportunities for biological activity modulation and chemical derivatization.

References

2003. Carteolol. Pharmaceutical Substances.
URL: https://pharmaceutical-substances.thieme.com/ps/search-results?docUri=KD-03-0053

1997. Metabolism of carteolol by cDNA-expressed human cytochrome P450. European Journal of Clinical Pharmacology, 52(5).
DOI: 10.1007/s002280050322