10-Ethyl-3-methylpyrimido[4,5-b]quinoline-2,4-dione
[CAS 59997-14-7]

Identification

• Classification: Pharmaceutical intermediate >> Heterocyclic compound intermediate >> Quinoline compound
• Name: 10-Ethyl-3-methylpyrimido[4,5-b]quinoline-2,4-dione
• Molecular Formula: C14H13N3O2
• Molecular Weight: 255.27
• CAS Registry Number: 59997-14-7
• SMILES: CCN1C2=CC=CC=C2C=C3C1=NC(=O)N(C3=O)C

Properties

• Density: 1.3±0.1 g/cm³ Calc.^*
• Boiling point: 389.2±52.0 °C 760 mmHg (Calc.)^*
• Flash point: 189.2±30.7 °C (Calc.)^*
• Index of refraction: 1.672 (Calc.)^*

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

Discovery and Applications

10-Ethyl-3-methylpyrimido[4,5-b]quinoline-2,4-dione is a fused nitrogen-containing heteroaromatic compound composed of a pyrimidoquinoline core bearing ethyl and methyl substituents and two carbonyl groups. Structurally, it belongs to the broader family of bicyclic or polycyclic fused pyrimidine derivatives, which combine a pyrimidine ring with a quinoline-type aromatic system.

The central structural feature is the pyrimido[4,5-b]quinoline framework. This fused ring system contains multiple nitrogen atoms incorporated into an extended conjugated aromatic structure. Fusion of heterocyclic rings increases rigidity and produces an expanded π-electron system, which can strongly influence electronic properties and intermolecular interactions.

The designation "2,4-dione" indicates the presence of two carbonyl groups located at positions 2 and 4 of the pyrimidine portion of the fused system. These carbonyl functionalities create a pyrimidinedione motif, structurally related to other diketone-containing heterocyclic systems. The carbonyl groups are among the most electronically polarized regions of the molecule and act as hydrogen-bond acceptors.

Compounds containing pyrimidinedione systems may exhibit keto–enol tautomerism in some structural contexts, although the dominant form depends on substitution pattern and electronic stabilization within the fused ring system. The extended aromatic structure can influence the distribution of electron density and contribute to stabilization of specific tautomeric forms.

The methyl substituent at the 3-position and the ethyl substituent at the 10-position modify the steric and electronic properties of the fused heterocycle. Alkyl substituents generally donate electron density through inductive effects and increase hydrophobic character. They can also affect molecular packing and solubility behavior.

The fused aromatic system is expected to be largely planar or nearly planar across much of the ring structure because aromatic conjugation favors delocalization of π-electrons. Such planarity can influence intermolecular interactions, including π–π stacking between aromatic systems in the solid state.

From a physicochemical perspective, the molecule contains both hydrophobic and polar regions. The fused aromatic rings and alkyl substituents contribute hydrophobic character, while the carbonyl groups and ring nitrogens introduce polarity. The nitrogen atoms and carbonyl oxygens may participate in hydrogen-bonding interactions as acceptors.

The most chemically reactive sites are likely to include the carbonyl groups and selected positions on the heteroaromatic ring influenced by nitrogen substitution. The ring nitrogens may also undergo protonation under acidic conditions, altering electronic properties and solubility.

Without verified literature specific to this compound, additional statements regarding biological activity, pharmaceutical properties, or specific applications should not be made. Based on established structural information, it can be reliably described as a fused pyrimidoquinoline diketone derivative with a rigid heteroaromatic framework and multiple electron-deficient functional features.

References

2008. Antitumor studies -- part 2: structure-activity relationship study for flavin analogs including investigations on their in vitro antitumor assay and docking simulation into protein tyrosine kinase. European Journal of Medicinal Chemistry.
DOI: 10.1016/j.ejmech.2007.10.011