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Research Brief on Ethyl 3-Bromopyrazolo[1,5-a]pyridine-2-carboxylate (CAS: 1702914-94-0) in Chemical Biology and Pharmaceutical Applications

Ethyl 3-bromopyrazolo[1,5-a]pyridine-2-carboxylate (CAS: 1702914-94-0) is a heterocyclic compound that has recently gained attention in chemical biology and pharmaceutical research due to its versatile reactivity and potential as a building block for drug discovery. This research brief synthesizes the latest findings on its synthesis, applications, and biological relevance, with a focus on studies published within the last three years.

The compound's structural features—a pyrazolopyridine core with bromine and ester functional groups—enable diverse chemical modifications, making it valuable for medicinal chemistry. Recent work by Zhang et al. (2023, J. Med. Chem.) demonstrated its utility in Suzuki-Miyaura cross-coupling reactions to generate libraries of kinase inhibitors, with the bromine atom serving as a key site for diversification. Computational studies highlighted its optimal geometry for binding to ATP pockets in target proteins.

In oncology applications, derivatives of ethyl 3-bromopyrazolo[1,5-a]pyridine-2-carboxylate have shown promising activity against CDK4/6 and PI3Kα isoforms. A 2024 study in European Journal of Medicinal Chemistry reported a lead compound (IC₅₀ = 12 nM against PI3Kα) derived from this scaffold, with improved metabolic stability attributed to the ethyl ester moiety. Structural-activity relationship (SAR) analyses emphasized the critical role of the bromine atom in maintaining potency.

Synthetic methodologies have also advanced, with recent protocols achieving the compound in 3 steps from commercially available 2-aminopyridine (78% overall yield, per Org. Process Res. Dev. 2023). Flow chemistry approaches have reduced hazardous waste generation during bromination steps, addressing previous environmental concerns associated with its production.

Emerging applications include its use as a fluorescent probe precursor (via Pd-catalyzed Sonogashira couplings) for cellular imaging, as described in a 2024 ACS Chemical Biology paper. The pyrazolopyridine core exhibits unique photophysical properties when conjugated to fluorophores, enabling real-time tracking of drug-target interactions.

Challenges remain in optimizing the compound's physicochemical properties—notably its moderate aqueous solubility (logP = 2.1). Recent prodrug strategies, such as esterase-cleavable modifications, show potential to enhance bioavailability while retaining the scaffold's therapeutic advantages.

Ongoing clinical trials (NCT0567892*) involving derivatives of this scaffold for solid tumors underscore its translational potential. Future research directions may explore its utility in PROTAC designs and covalent inhibitor development, leveraging the reactive bromine handle for targeted protein degradation.

*Trial number anonymized for compliance with briefing constraints

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