Chemical Identity and Properties

4-Chloro-5-methyl-7H-pyrrolo[2,3-d]pyrimidine (SKU: C174622) is a bicyclic heteroaromatic compound comprising a pyrimidine ring fused to a pyrrole ring. The chlorine substituent at the 4-position serves as an electrophilic handle for nucleophilic aromatic substitution (SNAr) reactions, while the methyl group at the 5-position modulates the electronic character and steric profile of the scaffold. The NH at the 7-position (pyrrole nitrogen) may require protection during multistep synthesis sequences.

Molecular Formula: C₇H₆ClN₃; Molecular Weight: 167.59 g/mol. The compound typically appears as a white to off-white crystalline solid. It is sparingly soluble in water but dissolves in polar aprotic solvents such as DMF, DMSO, and acetonitrile.

Safety, Storage, and Handling

Personal Protective Equipment (PPE): Always wear appropriate PPE when handling this compound, including chemical-resistant gloves (nitrile recommended), a laboratory coat, and safety goggles. Work in a well-ventilated fume hood to avoid inhalation of dust or vapors.

Storage: Store the compound in a tightly sealed container in a cool (2–8 °C recommended for long-term stability), dry, and well-ventilated area, protected from light and moisture. Keep away from incompatible materials such as strong bases, strong oxidizing agents, and reactive nucleophiles that could react with the C4-chloro group.

Disposal: Dispose of this compound and any contaminated materials in accordance with local, regional, and national regulations for halogenated organic waste. Do not pour into drains or the environment. Consult the Safety Data Sheet (SDS) for complete hazard information before use.

Solution Preparation and Reaction Protocol

Stock Solution Preparation: To prepare a stock solution, weigh the required amount of 4-chloro-5-methyl-7H-pyrrolo[2,3-d]pyrimidine using a calibrated analytical balance inside a fume hood. Dissolve in a suitable anhydrous polar aprotic solvent (e.g., anhydrous DMSO or DMF) with gentle stirring or sonication. Filter through a 0.22 µm PTFE syringe filter if a particle-free solution is required.

SNAr Displacement at C4: The C4-chloro group undergoes nucleophilic aromatic substitution with amines, alcohols, and thiol nucleophiles under mild to moderate conditions. A representative procedure: combine the compound (1.0 equiv.) with the desired amine nucleophile (1.1–2.0 equiv.) and a suitable base (e.g., triethylamine or DIPEA, 2.0 equiv.) in a polar solvent (e.g., isopropanol, DMF, or acetonitrile). Heat to 60–100 °C and monitor by TLC or LC-MS until reaction completion. Cool, quench with water, extract with ethyl acetate, wash with brine, dry over Na₂SO₄, filter, and concentrate under reduced pressure.

N7 Protection: When the pyrrole NH must be protected prior to further functionalization, standard protecting groups such as SEM (2-(trimethylsilyl)ethoxymethyl) or tosyl (Ts) groups may be installed using NaH as base in anhydrous THF or DMF at 0 °C to room temperature.

Note: Specific reaction temperatures, equivalents, and solvents should be optimized for each target transformation. Monitor all reactions by appropriate analytical methods (TLC, HPLC, LC-MS).

Applications in Medicinal Chemistry

The pyrrolo[2,3-d]pyrimidine scaffold is a privileged structure in medicinal chemistry, recognized for its ability to mimic the purine ring system found in ATP. This structural mimicry makes derivatives of 4-chloro-5-methyl-7H-pyrrolo[2,3-d]pyrimidine valuable starting materials and intermediates for the development of kinase inhibitors targeting a broad range of kinases, including tyrosine kinases and cyclin-dependent kinases (CDKs).

The reactive C4-chloro group enables rapid diversification of the scaffold via SNAr chemistry, facilitating the construction of focused compound libraries for structure-activity relationship (SAR) studies. The 5-methyl group provides additional steric and electronic modulation, which can influence binding affinity and selectivity toward specific kinase targets. Researchers in oncology, immunology, and virology drug discovery programs frequently employ this intermediate in multi-step total syntheses of clinical candidates.

Quality Control and Analytical Characterization

Upon receipt of 4-chloro-5-methyl-7H-pyrrolo[2,3-d]pyrimidine (SKU: C174622), inspect the material for physical appearance (white to off-white solid) and confirm the lot-specific Certificate of Analysis (CoA) for purity, identity, and compliance with specification.

Recommended analytical methods:

• Purity: HPLC (reverse-phase C18 column; UV detection at 254 nm or 280 nm) or GC for volatile impurity profiling.
• Identity: ¹H NMR (DMSO-d₆ or CDCl₃): characteristic signals for the pyrrole NH, aromatic/vinyl protons, and methyl group. High-resolution mass spectrometry (HRMS) for exact mass confirmation.
• Water Content: Karl Fischer titration to confirm low moisture content, particularly important for moisture-sensitive reactions.

Store opened material under inert atmosphere (nitrogen or argon) when possible to minimize exposure to atmospheric moisture and prolong shelf life.