4-Chloro-5H-pyrrolo[2,3-d]pyrimidin-6(7H)-one is a fused heteroaromatic compound consisting of a pyrimidine ring fused to a pyrrole, with a chlorine atom at position 4 and a keto group at position 6. Its molecular formula is C5H3ClN3O, with a molecular weight of approximately 149.56 g/mol. The fused ring system is electron-rich and planar, while the keto group introduces a site of electrophilicity, and the chloro substituent provides a handle for further chemical modification via nucleophilic substitution or cross-coupling reactions.
The compound is commonly synthesized through cyclization of appropriate substituted precursors. One approach involves condensation of a 4-chloro-substituted pyrimidine derivative with an α-amino ketone or equivalent to construct the fused pyrrolo[2,3-d]pyrimidine skeleton. Reaction conditions are optimized to control regioselectivity and prevent overhalogenation or side reactions. Alternative methods include multi-step sequences in which the keto group is introduced via oxidation or selective formylation followed by cyclization to complete the fused heterocyclic system.
Chemically, 4-chloro-5H-pyrrolo[2,3-d]pyrimidin-6(7H)-one exhibits reactivity at the chlorine atom and the keto group. The chlorine atom can undergo nucleophilic substitution, enabling the introduction of various substituents at position 4. The keto functionality is capable of forming enolates, imines, or hydrazones, providing additional sites for derivatization. The fused ring system also allows for hydrogen bonding and π–π interactions, which can influence solubility, crystallization, and binding properties in biological or chemical systems.
The compound is typically a solid at room temperature and is soluble in polar organic solvents such as dimethylformamide, dimethyl sulfoxide, and acetone. It is chemically stable under ambient conditions but should be protected from strong acids, bases, or oxidizing agents that could hydrolyze the chlorine or alter the keto functionality. The planar fused system contributes to rigidity and defines steric constraints that affect its chemical reactivity and interaction with other molecules.
In practical applications, 4-chloro-5H-pyrrolo[2,3-d]pyrimidin-6(7H)-one is widely used as a building block in medicinal chemistry and heterocyclic synthesis. Its chlorine substituent allows selective functionalization via nucleophilic substitution or palladium-catalyzed cross-coupling reactions, while the keto group enables further derivatization for the preparation of bioactive molecules, enzyme inhibitors, and nucleoside analogues. The fused pyrrolopyrimidine core is a common motif in pharmacologically active compounds, and the molecule serves as a versatile intermediate for the design of structurally diverse heterocycles.
Overall, 4-chloro-5H-pyrrolo[2,3-d]pyrimidin-6(7H)-one combines a reactive keto group, a halogen substituent, and a rigid fused heteroaromatic system, making it a valuable intermediate in organic synthesis and medicinal chemistry. Its defined electronic and steric features enable selective functionalization, supporting the synthesis of complex molecules with potential biological and chemical applications.
References
2012. An Efficient Synthesis of 4-Chloro-2-pyrrolino[2,3-d]pyrimidin-6-one and Its 7-Substituted Analogues. Synthesis.
DOI: 10.1055/s-0031-1290408
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![CAS # 346599-63-1, 4-Chloro-5H-pyrrolo[2,3-d]pyrimidin-6(7H)-one](/structures/346599-63-1.gif)
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