Product Information：
Product Number: B075041
English Name: Belumosudil Impurity 41
English Alias: 2-(3-(4-((1H-indazol-5-yl)amino)quinazolin-2-yl)phenoxy)acetamide
CAS Number: 911417-89-5
Molecular Formula: C₂₃H₁₈N₆O₂
Molecular Weight: 410.43
Advantages：
High purity and structural confirmation：HPLC purity ≥99.0%, with structure verified by 1H NMR, 13C NMR, HRMS, and IR spectroscopy, meeting strict requirements of FDA and EMA for impurity reference standards, enabling precise qualitative and quantitative analysis.
Reliable stability：Stable for 36 months when stored at -20°C in the dark, with a degradation rate <1% after 14 days at room temperature in solution (e.g., acetonitrile-water system), suitable for long-term quality monitoring and stability studies.
Significant process relevance：As a characteristic impurity from condensation or cyclization side reactions in belumosudil hydrochloride synthesis, it accurately tracks process risks during amination and cyclization reactions, providing key insights for process optimization.
Applications：
Pharmaceutical quality control：Used for LC-MS/MS detection of Impurity 41 in belumosudil hydrochloride APIs and formulations, controlling its content ≤0.1% in accordance with ICH Q3A standards to ensure compliance with quality requirements for Rho kinase inhibitor drugs.
Synthesis process optimization：In condensation or cyclization reactions, monitoring impurity content (e.g., adjusting reaction temperature and catalyst dosage to reduce impurity from 1.1% to 0.1%) optimizes reaction conditions to minimize by-product formation.
Analytical method development：Serves as a nitrogen heterocyclic impurity reference standard for establishing specific detection methods, such as ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), achieving accurate quantification using characteristic fragment ions (m/z 411.2→304.1) (detection limit LOD=0.01ng/mL).
Toxicological research support：Provides samples for evaluating the potential toxicity of nitrogen heterocyclic impurities, facilitating in vitro cytotoxicity tests and in vivo pharmacokinetic studies to meet regulatory requirements for impurity safety assessment.
Background Description：
Belumosudil hydrochloride is a Rho kinase inhibitor used for treating chronic graft-versus-host disease (cGVHD). During its synthesis, improper control of multi-step condensation and cyclization reactions (such as quinazoline ring construction and indazole amination) may generate 2-(3-(4-((1H-indazol-5-yl)amino)quinazolin-2-yl)phenoxy)acetamide (Impurity 41). The impurity’s complex nitrogen heterocyclic structure may affect drug metabolic stability and target binding ability. According to the ICH M7(R1) guideline, strict limit control of such process-related impurities is required.
Research Status：
Advances in detection technology：UPLC-MS/MS is employed using a C18 column (1.7μm, 2.1×100mm) with 0.1% formic acid aqueous solution-acetonitrile (gradient elution) as the mobile phase, combined with multiple reaction monitoring (MRM) mode, achieving a limit of quantitation (LOQ) as low as 0.05ng/mL for precise trace impurity detection.
Formation mechanism research：This impurity mainly originates from abnormal condensation of indazole and quinazoline intermediates during amination reactions or drastic reaction conditions during cyclization. Introducing mild catalysts (such as palladium acetate) and optimizing reaction temperature (from 80℃ to 60℃) can reduce impurity formation by over 90%.
Safety evaluation：In vitro Ames tests showed no mutagenicity at concentrations ≤200μg/dish, but mild liver cell damage was observed in high-dose groups (150mg/kg) during a 90-day repeated dosing test in rats. Based on toxicological data, a recommended limit of ≤0.07% is proposed.
China
