6-Benzyl-4-chloro-5,6,7,8-tetrahydropyrido[4,3-d]pyrimidine hydrochloride
[CAS# 944902-64-1]

Identification

• Classification: Pharmaceutical intermediate >> Heterocyclic compound intermediate >> Pyrimidine compound
• Name: 6-Benzyl-4-chloro-5,6,7,8-tetrahydropyrido[4,3-d]pyrimidine hydrochloride
• Synonyms: 4-chloro-5,6,7,8-tetrahydropyrido[4,3-d]pyrimidine
• Molecular Formula: C₁₄H₁₄ClN₃^.HCl
• Molecular Weight: 296.19
• CAS Registry Number: 944902-64-1
• SMILES: C1CNCC2=C1N=CN=C2Cl

Properties

• Density: 1.3±0.1 g/cm³ Calc.^*
• Boiling point: 321.5±42.0 ºC 760 mmHg (Calc.)^*
• Flash point: 148.2±27.9 ºC (Calc.)^*
• Index of refraction: 1.57 (Calc.)^*

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

Safety Data

• Hazard Symbols: GHS07 Warning
• Hazard Statements: H302-H315-H319-H335
• Precautionary Statements: P261-P264-P270-P271-P280-P302+P352-P304+P340-P305+P351+P338-P312-P330-P362-P403+P233-P501

Discovory and Applicatios

6-Benzyl-4-chloro-5,6,7,8-tetrahydropyrido[4,3-d]pyrimidine hydrochloride is a synthetic heterocyclic compound belonging to the pyridopyrimidine class. The pyrido[4,3-d]pyrimidine framework consists of a fused bicyclic system in which a pyridine ring is condensed with a pyrimidine ring. Such fused nitrogen-containing heterocycles have been studied extensively in medicinal chemistry because they provide structural motifs capable of interacting with biological targets through hydrogen bonding and aromatic stacking interactions. The hydrochloride designation indicates that the compound is isolated as a salt formed by protonation of a basic nitrogen atom and association with chloride.

The development of pyridopyrimidine derivatives followed earlier investigations into purine and pyrimidine analogs. Because purines and pyrimidines are fundamental components of nucleic acids, chemists explored related fused ring systems in the mid-twentieth century to evaluate their biological activity. Substituted pyridopyrimidines were synthesized as part of systematic programs aimed at discovering compounds with antimicrobial, anticancer, or enzyme-inhibitory properties. The presence of substituents such as chloro groups and benzyl moieties allowed researchers to modify lipophilicity, electronic properties, and steric effects in order to optimize biological performance.

The 4-chloro substituent in this compound is consistent with common synthetic strategies for functionalizing heterocyclic cores. Chloro groups on activated heteroaromatic systems can serve as leaving groups in nucleophilic substitution reactions, enabling further derivatization. In medicinal chemistry research, 4-chloropyrimidine and related motifs have frequently been used as intermediates for introducing amine or other nucleophilic substituents. The benzyl group at the 6 position contributes hydrophobic character and can influence binding interactions with biological macromolecules.

Compounds within the tetrahydropyrido[4,3-d]pyrimidine family have been reported in the scientific literature as kinase inhibitors and as modulators of signaling pathways. The fused heterocyclic scaffold is capable of occupying ATP-binding sites in certain enzymes, and structural modification at positions corresponding to those in 6-benzyl-4-chloro derivatives has been explored to improve selectivity and potency. Research publications and patents have described related structures in the context of pharmaceutical development, reflecting the broader application of this heterocyclic system in drug discovery.

The hydrochloride salt form is commonly prepared to improve the stability, crystallinity, and aqueous solubility of basic heterocyclic compounds. Formation of the hydrochloride facilitates purification and handling, and it is a standard practice in the preparation of small-molecule research compounds. Solid-state characterization methods such as melting point determination, infrared spectroscopy, and nuclear magnetic resonance spectroscopy are typically used to confirm structure and purity.

In addition to biological investigations, substituted pyridopyrimidines have been studied for their synthetic versatility. The partially saturated tetrahydro ring system allows further functionalization, and the presence of multiple nitrogen atoms provides coordination sites for interaction with acids or metals under appropriate conditions. As a result, compounds of this type serve both as intermediates in heterocyclic synthesis and as candidates in pharmacological screening programs.

The documented discovery and application of pyridopyrimidine derivatives demonstrate the importance of fused nitrogen heterocycles in modern organic and medicinal chemistry. 6-Benzyl-4-chloro-5,6,7,8-tetrahydropyrido[4,3-d]pyrimidine hydrochloride represents a structurally defined example within this established class of research compounds.

References

2023. A new preparation method for APDS therapeutic drugs. CN Patent.
URL: CN-117534672-A

2021. Pyridine derivative and use thereof. EP Patent.
URL: EP-4406948-A1

2021. Pyridine derivative and use thereof. US Patent Application.
URL: US-2025145589-A1