📰 5-Bromo-1H-indazole (CAS 53857-57-1): A Versatile Brominated Indazole Building Block for Pharmaceutical and Organic Synthesis

September 18, 2026

1、Product Overview

5-Bromo-1H-indazole, also known as 5-Bromoindazole, is a brominated heterocyclic compound containing an indazole core and a bromine substituent at the 5-position. The molecule combines a fused benzene-pyrazole framework with an N–H functionality and an aryl bromide site, providing multiple opportunities for downstream structural modification.

The molecular formula of 5-Bromo-1H-indazole is C₇H₅BrN₂, with a molecular weight of 197.03 g/mol. As a brominated indazole building block, it is particularly relevant to organic synthesis where controlled modification of the indazole scaffold is required.

The 5-bromo substituent provides a useful reaction handle for carbon-carbon and carbon-heteroatom bond formation. Under suitable conditions, it can participate in cross-coupling reactions such as Suzuki, Heck and Sonogashira coupling, allowing different aryl, heteroaryl, alkenyl or alkynyl groups to be introduced at the 5-position.

At the same time, the N–H group of the indazole ring provides an additional site for chemical modification, including N-alkylation, N-acylation and N-sulfonylation. This combination of C- and N-functionalization makes 5-Bromo-1H-indazole a useful intermediate for pharmaceutical research, medicinal chemistry, substituted indazole development and customized organic synthesis.

2、Basic Product Information

1）Product Name: 5-Bromo-1H-indazole

2）Chinese Name: 5-溴吲唑

3）CAS NO.: 53857-57-1

4）Synonyms: 5-Bromoindazole; 5-Bromo-1H-indazole

5）Molecular Formula: C₇H₅BrN₂

6）Molecular Weight: 197.03 g/mol

7）Structural Formula:

8）Appearance: Solid

9）Chemical Class: Brominated indazole heterocycle

10）Functional Groups: Aryl bromide and indazole N–H

11）Main Positioning: Pharmaceutical intermediate; medicinal chemistry building block; organic synthesis intermediate

12）Product Manager Email: Echo@coreychem.com

3、Frequently Asked Questions (FAQ)

Frequently Asked Questions

1）What makes 5-Bromo-1H-indazole a practical starting material for multi-step synthesis?

5-Bromo-1H-indazole combines a pre-formed indazole core with a well-defined C5 bromine handle. This means the heterocyclic framework and a reactive position are already built into the molecule, which can reduce the need to introduce the bromine later in the route. It is therefore useful for route screening, analogue preparation and the synthesis of more complex indazole-containing intermediates.

2）Which substituents can be introduced at the 5-position, and by what chemistry?

The C5 bromide can participate in palladium-catalyzed cross-coupling reactions such as Suzuki, Heck, Sonogashira and Buchwald-Hartwig couplings. Depending on the coupling partner, aryl, heteroaryl, alkenyl, alkynyl or amino groups can be introduced. This makes the compound suitable for preparing C5-substituted indazole derivatives with different electronic and steric properties.

3）How should the indazole N-H group be handled during synthesis?

The indazole N-H can remain free or be protected or functionalized depending on the target route and selectivity requirements. If a reaction at the C5 bromide needs to avoid N participation, N-protection or temporary N-functionalization may be considered. In other cases, direct N-alkylation, N-acylation or N-sulfonylation can be used as part of the desired structure. The choice should be based on the specific reaction sequence and purification strategy.

4）Why choose 5-Bromo-1H-indazole instead of unsubstituted indazole?

Using 5-Bromo-1H-indazole avoids an additional bromination or halogenation step and provides position-specific functionalization at C5. This can improve regiocontrol and simplify route design when the target molecule requires a substituent at the 5-position. It also allows the indazole core to be retained while different groups are introduced at a defined position.

5）What purity, analytical data and supply options are available?

5-Bromo-1H-indazole can be supplied with purity ≥99%. Batch-specific analytical data, such as HPLC and NMR, and a COA can be provided upon request to support quality evaluation and downstream synthesis. Standard packaging includes 100 g/bottle, 1 kg/bottle and 10 kg/barrel, with custom packaging available. For projects requiring route development or larger quantities,

4、Application Cases

1）Pharmaceutical Intermediate Synthesis

5-Bromo-1H-indazole can be used as a brominated heterocyclic building block for the synthesis of pharmaceutical intermediates containing an indazole scaffold.

The fused indazole structure provides a defined heterocyclic framework, while the 5-bromo substituent offers a reactive aryl bromide site for further elaboration. Through suitable cross-coupling reactions, chemists can introduce aryl, heteroaryl, alkenyl, alkynyl or other substituents, enabling the construction of more complex pharmaceutical intermediates.

2）Medicinal Chemistry and SAR Studies

5-Bromo-1H-indazole can serve as a useful starting material for medicinal chemistry and structure-activity relationship studies.

The 5-bromo group allows researchers to introduce different substituents at a defined position on the indazole ring through reactions such as Suzuki, Heck and Sonogashira coupling. By preparing a series of C5-substituted analogues while retaining the same indazole core, researchers can systematically investigate the influence of structural modifications on compound properties and biological activity.

3）Organic Synthesis and Cross-Coupling Chemistry

5-Bromo-1H-indazole is a useful intermediate in organic synthesis because its aryl bromide provides a convenient handle for C–C and C–heteroatom bond formation.

The bromine atom can be replaced or transformed through different coupling strategies, while the indazole N–H group can undergo additional functionalization. The combination of these two reaction sites allows chemists to develop substituted heterocycles, functionalized aromatic compounds and more complex organic molecules through sequential synthetic steps.

4）Synthesis of Substituted Indazole Derivatives

5-Bromo-1H-indazole can be used as an intermediate for preparing a broad range of 5-substituted indazole derivatives.

The 5-position can be modified through appropriate coupling reactions to introduce aromatic, heteroaromatic, alkynyl or other functional groups. At the same time, the nitrogen atoms within the indazole ring provide additional opportunities for N-functionalization, allowing researchers to generate structurally diversified indazole compounds for pharmaceutical and chemical research.

5）Customized Synthesis and Process Development

It can be considered as a starting material for customized synthesis and process-development projects involving indazole-based compounds.

Its defined molecular structure and two useful functionalization sites—the 5-bromo group and indazole N–H—provide flexibility during route design and intermediate development. This makes it suitable for projects requiring specific indazole derivatives, research intermediates or more complex pharmaceutical building blocks, with the synthetic route adapted according to the target structure and process requirements.

5、Safety and Storage

1）Store 5-Bromo-1H-indazole in a tightly closed container in a cool, dry and well-ventilated area.

2）Protect the material from excessive moisture, heat and direct sunlight during storage.

3）Keep the product away from strong oxidizing agents and other incompatible chemicals.

4）Avoid unnecessary generation or inhalation of dust when handling the solid material. Appropriate laboratory protective equipment should be used according to the applicable SDS.

5）During transportation and storage, use clean, dry and properly sealed packaging to help maintain product quality.

6）Customers should consult the supplier’s current SDS and technical specification for detailed information on handling, personal protection, storage and transportation requirements.