Indazole (Indazole) Scaffold Explained: How Adjacent Nitrogens, Tautomerism, and Substitution Sites Make H-Bonding and Acid–Base Behavior Tunable

1.A practical question: why does a “small scaffold” keep showing up?

In drug and functional-molecule R&D, recurring bottlenecks usually concentrate on three things: whether a molecule can bind its target stably, whether it can dissolve/form salts, and whether it can maintain controllable stability and metabolism in vivo or under process conditions. Often, the solution cannot be achieved by merely “swapping a functional group”. Instead, you need a scaffold that simultaneously offers more suitable interaction sites and a tunable microstate space (acid–base behavior / tautomerism).

Indazole is repeatedly used because its two adjacent nitrogens plus tautomerism enable systematic, apples-to-apples comparisons across H-bonding patterns, acid–base/charge states, and substitution/position expansion. This turns optimization from trial-and-error into iterative tuning of controllable variables.

2.Definition and essentials: what is indazole?

Indazole is a fused aromatic nitrogen heterocycle: a benzene ring fused with a pyrazole ring. It is also commonly written as benzopyrazole (benzopyrazole, or benzo[d]pyrazole / 1,2-benzopyrazole).

Using the most common parent 1H-indazole as a representative:

(1). Molecular formula: C₇H₆N₂

(2). CAS: 271-44-3

 

 

3.Structural features: how two “adjacent nitrogens” determine properties

Structural feature	Corresponding property changes	Common usage
Tautomerism (mainly 1H ↔ 2H; literature may also mention 3H as a potential form)	The position of the N–H shifts; the H-bond donor/acceptor map changes accordingly; reactions may proceed via different pathways	N-substitution (alkylation/acylation) often discusses N1/N2 regioisomers; in scaffold comparisons, used to rationalize differences in activity/selectivity
Switchable acid–base and charge states (neutral indazole ⇄ indazolate anion; neutral indazole ⇄ indazolium cation)	Changing charge state can strongly affect solubility, coordination ability, and H-bonding/polarity	Salt formation / solubility window, coordination/metal systems, and reaction design under strong base or strong acid conditions
Stackable interactions (two nitrogens + fused aromatic π surface)	More likely to provide both directional H-bonding and aromatic contact surfaces; under suitable conditions, can also serve as an N-donor coordination site	Multipoint interactions in drug binding sites; as a nitrogen-containing ligand fragment in materials/coordination systems
Multiple substitution sites (N sites + positions adjacent on the five-membered ring + multiple benzene-ring sites)	Large SAR space: electronics/hydrophobicity/sterics can be tuned systematically to manage selectivity, exposure, and metabolically sensitive sites	“Position scanning” and series optimization in drugs/functional molecules; also used as an intermediate platform for further diversification

Notes:

① 1H is the dominant (most common/more stable) tautomer; 2H interconverts but is usually a smaller fraction; 3H can typically be treated as a rarely used potential form. In unsubstituted parent/simple derivatives, discussions often default to 1H. However, for N-substituted derivatives (especially in drug IUPAC naming), 1H/2H labels are frequently used for naming and site identification and should not be directly equated to tautomer populations in solution.

② The indazole ring is a very weak base: under neutral conditions it is mainly neutral; it is more readily protonated only under strongly acidic conditions and deprotonated only under strongly basic conditions.

③ N-site substitution should consider N¹/N² regioisomerism; tautomerism and conditions can affect regioselectivity.

4.Classification: first identify the “molecular state”, then identify “which position is modified”

4.1 Classification by “molecular state” (clarify neutral/tautomeric/charged first)

Molecular state	How to recognize	When you typically encounter it
Neutral 1H-indazole (most common default form)	The structure is usually drawn with one N bearing H (N–H) and no overall charge	Most drug-scaffold discussions; routine neutral molecule design
Tautomerism-related systems (mainly 1H ↔ 2H)	Within the same scaffold, H can transfer between the two nitrogens (tautomerism)	Discussions of N-substitution (alkylation/acylation), regioselectivity, and regioisomer ratios
Indazolate (anion after deprotonation)	N–H is absent and there is an overall negative charge (often as a salt)	Strong base conditions; when stronger N-donor/coordination ability is desired; certain reaction designs
Indazolium (cation after protonation)	An additional proton and an overall positive charge (often as a salt)	Strong acid / salt form conditions; discussions of charge state in acidic media

4.2 Classification by “modification site” (“modify N / modify the five-membered ring / modify the benzene ring”)

Modification site	What you are typically trying to solve	Common directions of change
N-site substitution (N1/N2)	Lock/remove N–H, adjust polarity and binding mode, or build an N-substituted derivative library	Presence/absence of H-bond donor changes; tautomer behavior may be “locked”; N1/N2 regioisomers may appear
Substitution/side chains near the five-membered ring	Tune key interaction geometry and spatial orientation, or address metabolically sensitive sites	More directly affects docking pose, local electronics, and reaction/metabolism sensitivity points
Benzene-ring substitution	Fine-tune hydrophobic volume, π-surface contacts, and electronic effects to improve selectivity and exposure windows	Often used for “fine adjustment”: stepwise alignment of lipophilicity, selectivity, and stability windows

5.Applications: Turning “Structure Determines Properties” into Three High-Frequency Workstreams

High-frequency application workstream	What indazole does (linked to structural features)	Checkable representative examples	Notes
Drug discovery: a commonly used heteroaromatic scaffold	Two nitrogens provide a designable H-bond map + a fused aromatic π surface; positions can be expanded for series-based SAR (same-scaffold controls are easier)	Pazopanib: studies have directly performed structure optimization by modifying the indazole ring in pazopanib; Niraparib: metabolism/stability evaluations explicitly treat the indazole moiety as one tunable fragment; Benzydamine: an indazole derivative used for local anti-inflammatory/analgesic effects (often grouped under NSAIDs; commonly formulated as the hydrochloride salt)	Do not expect a dramatic solubility increase by relying only on “protonation of the indazole ring itself”: a review summary reports an indazolium/indazole pKₐ ~ 1.04, indicating indazole is a very weak base; real drugs more often rely on an appended protonatable side chain, plus salt/co-crystal strategies, and substitution-driven tuning of hydrophobicity and H-bond networks to reach the desired property window.
Synthesis & fine chemicals: an agrochemicals/dyes/intermediate platform	The indazole scaffold is planar and multi-position functionalizable, enabling you to first build a “further-expandable” intermediate, then rapidly diversify in parallel (coupling, amidation, N-substitution, etc.)	Review statements: the indazole core is an important component in agrochemicals, dyes, and key pharmaceutical intermediates; a checkable “dye example”: patents and application descriptions exist for indazole azo dyes	The most common practical issue when using it as an intermediate: N-substitution frequently encounters N1/N2 regioisomerism and strong condition dependence (you should plan for this in route design and purification early).
Coordination & materials: an N-donor ligand unit (coordination polymers / MOFs)	The two nitrogens can serve as N-donor sites; introducing a “linker handle” such as carboxylic acid makes coordination networks easier to form, extending toward luminescence and porous adsorption	Checkable literature reports include coordination polymers built from 1H-indazole-4-carboxylic acid; Zn-MOFs based on 1H-indazole-5-carboxylic acid; and metal coordination polymers using 1H-indazole-3-carboxylic acid	“Two nitrogens coordinate; the carboxylate connects/creates the network.” Dimensionality (1D/2D/3D) and function (emission/adsorption) depend more on the metal node and auxiliary ligands.

6.Five Most Common Modification Entry Points for Indazole

Structural variable to modify	Property variable most often “tuned” (main impact)	Where it lands in use	Notes (reminders)
Tautomerism / molecular state (mainly 1H ↔ 2H)	H-bond donor/acceptor positions and local polarity	Use same-scaffold controls to explain differences in activity/selectivity; understand/predict pathway differences during N-substitution	3H is usually not treated as a common dominant form; discussions mainly focus on 1H/2H
N site: keep NH vs N-substitution (N1/N2)	Presence/absence of an H-bond donor; overall polarity/coordination mode; may introduce regioisomers	Solubility/salt strategy; fine-tuning binding mode; building an N-substituted derivative library	N1/N2 regioisomerism is a common real-world issue—plan ahead in route design and purification
Benzene-ring substitution (electronic / hydrophobic)	Lipophilicity and hydrophobic contact surface; selectivity/exposure window	“Position-scanning” SAR: fine-tune selectivity, exposure, and stability	Often used for “fine adjustments”; small-step, controlled comparisons are usually better than one big change
Substitution/side chains near the five-membered ring	Spatial vectoring and key interaction geometry; metabolically sensitive sites	Improve docking pose and potency (IC₅₀/selectivity, etc.); manage metabolic hotspots	Changes near the di-nitrogen region tend to be more “sensitive”; systematic controls are recommended
Introduce linking/coordination handles (e.g., carboxylic acid)	Increased polarity and connectivity; stronger ability to build coordination networks	Coordination polymers/MOFs/functional materials; or treat it as an “expandable intermediate” for further derivatization	The stronger the “handle,” the more performance depends on specific metal nodes/conditions; use often shifts from drug-like to materials or intermediate-platform contexts

7.Product Navigation Table: Locate Indazole Chemicals by Research Task (Tables 1–4)

Research task / experimental need	Which table to check first	Why start with this table	Typical next step (common handoff)
Need approved/clinical drugs for activity benchmarking, method validation, impurity/degradation studies	Table 1: Drug APIs / reference standards	Provides checkable marketed drugs/tool compounds directly—best for controls and analytical work; avoids time/cost of resynthesis from intermediates	For structure expansion/metabolite analogs: then check Table 3 (functional handles / boronation handles) or Table 4 (position-scanning substitutions)
For target validation/cell assays, need a pharmacological indazole representative as a positive control	Table 1: Drug APIs / reference standards	Table 1 contains real drug-context representatives—fastest way to establish a baseline “effect vs no effect”	If the positive control is clear and you want SAR: move to Table 4 (position scanning) or Table 3 (rapid coupling-based expansion)
Build an indazole fragment library / scaffold starting point (beginning from the parent core)	Table 2: Parent cores & basic N-substituted building blocks	First decide whether you need N–H and confirm core availability—prevents repeated rework on N1 strategy later	If you need fast series at 3/5/6/7 positions: move to Table 4 (halogen/CF₃ etc. scanning) or Table 3 (boronic acid/Bpin for coupling)
Test whether N1 must be N–H or build N-substituted controls (microstate/H-bond-donor differences)	Table 2: Parent cores & basic N-substituted building blocks	N-substitution directly changes H-bond donor/acceptor patterns, pKₐ, and coordination behavior—one of the first variables to lock down in indazole SAR	If N1 can be locked: then go to Table 4 for position scanning, or Table 3 for coupling/linker-based expansion
Need a transformable handle to attach side chains/linkers (amidation, esterification, reductive amination, oxidation, etc.)	Table 3: Functional handles & boronation/coupling intermediates	Table 3 concentrates the most-used synthetic “handles” (acids/esters/aldehydes/nitriles/alcohols/amides), enabling rapid attachment of the indazole core to your desired modules	If you need diverse aryl/heteroaryl: prioritize Suzuki using Table 3 boronic acids/Bpin; for position scanning switch to Table 4
Goal is the fastest 10–50 derivative set for SAR (library/parallel synthesis)	Table 3: Functional handles & boronation/coupling intermediates	Boronic acids/Bpin (incl. preinstalled Bpin) are ideal for parallel Suzuki expansion; acids/aldehydes/alcohols also enable multiple parallel derivatization paths	Use Table 4 to pick halogenated positions → combine with Table 3 boron blocks for coupling; or directly assemble from Table 3 Bpin series
Doing Suzuki–Miyaura (or related) cross-coupling and need boronic acid/boronate ester/Bpin coupling blocks	Table 3: Functional handles & boronation/coupling intermediates	Table 3 groups boronic acids and Bpin together—easy to choose by position (3/5/6) and by stability/handling	If you have halo-indazoles: go to Table 4 to pick the matching halogenated site; if you want position-migration comparisons: Table 4 same-position halogen controls are more direct
Run position scanning / halogen scanning (3/4/5/6/7; Cl/Br/I/F) to optimize activity, selectivity, or ADME	Table 4: Position-substitution scanning	Table 4 is organized by position and substitution type (halogens, CF₃, amino/nitro/hydroxy, etc.)—best for grouped “same-position, different substituent” comparisons	To expand into larger substituents: couple Table 4 halogenated intermediates with Table 3 boronic acid/Bpin blocks
Tune solubility/salt/H-bonding via a polarity knob (amino, hydroxy, amide/acid)	Table 4 (check position amino/hydroxy/nitro first) + Table 3 (then acids/amides/alcohols/esters)	Table 4 provides position-level polar substituent controls; Table 3 provides stronger transformable polar handles (acid/amide/alcohol/aldehyde). Together they enable systematic property tuning	First use Table 4 to quickly compare “position effects,” then use Table 3 for deeper “handle derivatization/salt forms/linkers”
Need electronic-effect controls (nitro/nitrile/halogens/CF₃) to infer binding-site preference or metabolic stability trends	Table 4 (nitro/halogens/CF₃) + Table 3 (nitrile/amide)	Electronics are commonly scanned quickly via nitro, halogens, CF₃; nitrile/amide offer finer electronic + polarity tuning	If a position proves sensitive: return to Table 3 for coupling or handle derivatization to broaden structure space
Need scaffold hopping / topology controls (e.g., introduce related carbonyl-containing scaffolds)	Table 4: Position-substitution scanning (scaffold variants)	Table 4 includes variants such as “3-indazolinone,” suitable for topology/polarity controls within the same scaffold family	If a variant works, go back to Table 3 to add linkers/coupling expansion, or back to Table 2 to re-check the N1 strategy

Table 1｜Drug APIs / Reference Standards (Marketed Drugs / Tool Compounds)

Category	CAS No.	Aladdin Cat. No.	Name	Specification / Purity	Key Features & Applications
Drug API / Reference Standard | Targeted anti-tumor (kinase inhibitor)	444731-52-6	P125184	Pazopanib	Moligand™, ≥99%	A representative multi-target TKI containing an indazole core; used for API research, quality/impurity and degradation studies, method development, and activity benchmarking.
Drug API / Reference Standard | Targeted anti-tumor (kinase inhibitor)	319460-85-0	A129732	Axitinib	Moligand™, ≥99%	A representative indazole-scaffold VEGFR inhibitor; used for drug research, analytical reference, impurity profiling/stability, and process evaluation.
Drug API / Reference Standard | Anti-tumor (PARP inhibitor)	1038915-60-4	M127627	MK-4827 (Niraparib)	Moligand™, ≥98%	A representative PARP inhibitor containing an indazole core; used for pharmacology studies, analytical reference, and impurity/metabolite and degradation-pathway research.
Drug API / Reference Standard | Anti-inflammatory analgesic / topical use	132-69-4	B129528	Benzydamine Hydrochloride	≥97%	A representative indazole-class NSAID (commonly as the hydrochloride salt); used for drug research, analytical reference, impurity/degradation studies, and method validation.

Table 2｜Indazole Parent Core & Basic N-Substituted Building Blocks (Fragment Library / Scaffold Starting Points)

Category	CAS No.	Aladdin Cat. No.	Name	Specification / Purity	Key Features & Applications
Parent core / basic scaffold | General heterocycle building block	271-44-3	I473130	Indazole	98%	Core indazole scaffold (N-heteroaromatic fused ring) building block; commonly used for medicinal-chemistry scaffold construction, fragment libraries, and SAR starting points.
Parent core / N-substitution | N1 property tuning	13436-48-1	M628385	1-Methyl-1H-indazole	≥97%	N-methylation changes N–H acid–base/coordination behavior and H-bond donor properties; commonly used as a control to probe whether an N–H is required in structure–activity relationships.

Table 3｜Functional Handles (Carboxylic Acid / Ester / Aldehyde / Amide / Nitrile / Alcohol) & Boronation Coupling Intermediates (Boronic Acid / Bpin)

Category	CAS No.	Aladdin Cat. No.	Name	Specification / Purity	Key Features & Applications
Functional handle | Carboxylic acid (salt formation / amidation / linker)	4498-67-3	I157584	Indazole-3-carboxylic acid	≥98% (HPLC)	A 3-position carboxylic-acid “coupling handle”: facilitates salt formation and amidation for linker/side-chain extension, enabling iterative structure–property optimization.
Functional handle | Amide (polarity / H-bonding / metabolic-stability tuning)	90004-04-9	H195707	1H-Indazole-3-carboxamide	≥98%	The amide provides H-bonding and polarity; commonly used in lead optimization to tune solubility/exposure and as a control for receptor binding-mode comparisons.
Functional handle | Nitrile (further transformable / electronic-effect control)	50264-88-5	H184812	1H-Indazole-3-carbonitrile	≥98%	The nitrile is both small and electron-withdrawing; often used as an intermediate (further transformable) or to tune electronics and metabolic stability.
Functional handle | Aldehyde (reductive amination / condensation / ring-fusion entry)	5235-10-9	H589361	3-Formylindazole	≥98%	An aldehyde is an efficient “joining point”: commonly used for reductive amination, condensations, and ring-fusion construction to rapidly generate series of derivatives.
Functional handle | Alcohol (oxidizable / esterifiable / linker)	64132-13-4	H177036	1H-Indazole-3-methanol	≥97%	The hydroxymethyl group can be oxidized to an aldehyde/acid or esterified into a prodrug/linker; used to tune polarity and steric occupancy.
Functional handle | Ester (subsequent hydrolysis / amidation)	43120-28-1	M170339	Methyl 1H-indazole-3-carboxylate	≥97%	An ester is a “transformable handle”: readily hydrolyzed to the acid or converted to an amide/other derivatives for synthetic route handoffs.
Functional handle | Carboxylic acid (salt formation / amidation / linker)	61700-61-6	H135034	1H-Indazole-5-carboxylic acid	≥97%	A 5-position carboxylic acid suitable for amide/ester/salt-form controls; often used to build derivatives with improved solubility or connectivity.
Functional handle | Carboxylic acid (salt formation / amidation / linker)	704-91-6	H136017	1H-Indazole-6-carboxylic acid	≥97%	A 6-position carboxylic acid for salt formation and amidation expansion; often used to compare how an “acid handle” at different positions affects properties.
Functional handle | Alcohol (oxidizable / esterifiable / linker)	916902-55-1	H178209	(1H-Indazol-6-yl)methanol	≥97%	A 6-position hydroxymethyl is a common “connection point”: can be oxidized/esterified/etherified to introduce side chains, tuning sterics and polarity.
Boronic acid | Suzuki coupling handle	1310383-95-9	H678186	1H-Indazole-3-boronic acid	≥97%	A classic 3-position Suzuki entry point: enables rapid installation of aryl/heteroaryl groups, suitable for fragment growth and library synthesis.
Boronic acid | Suzuki coupling handle	338454-14-1	I169688	1H-Indazole-5-boronic acid	≥95%	Used in Suzuki–Miyaura to rapidly introduce aryl/heteroaryl groups; a key building block for 5-position substitution series.
Boronate ester | Bpin (Suzuki-friendly, stable and easy to handle)	862723-42-0	T177714	1H-Indazole-5-boronic acid pinacol ester	≥97%	The Bpin form is typically more stable and easier to weigh and scale in couplings; used for rapid construction of 5-substitution patterns.
Boronate ester | Bpin (Suzuki-friendly, stable and easy to handle)	937049-58-6	H331186	1H-Indazole-6-boronic acid pinacol ester	≥97%	A 6-position Bpin that supports rapid construction of diverse 6-substituted series; used for SAR expansion and lead optimization.
Boronated intermediate | Bpin (preinstalled coupling site)	1627722-97-7	M587523	1-Methyl-3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-indazole	≥98%	A Bpin-preinstalled “couplable site” on indazole: used for fast Suzuki–Miyaura installation of aryl/heteroaryl groups for SAR expansion and library synthesis.

Table 4｜Position Substitution (Amino / Nitro / Hydroxy / Alkyl / Trifluoromethyl / Halogenation / Scaffold Variants)

Category	CAS No.	Aladdin Cat. No.	Name	Specification / Purity	Key Features & Applications
Scaffold variant | Carbonyl-containing scaffold (property control)	7364-25-2	H134010	3-Indazolinone	≥97%	An indazole-related scaffold featuring a lactam: provides stronger H-bond acceptor/polar features; used for scaffold hopping and property controls.
Polar substitution | Amino (derivatization & salt-form window)	874-05-5	A134463	3-Aminoindazole	≥97%	A 3-position amino enables rapid installation of acyl/sulfonyl groups; used to tune H-bonding and solubility and to build bioactive derivatives.
Polar substitution | Amino (derivatization & salt-form window)	19335-11-6	A113923	5-Aminoindazole	≥98%	Enables fast diversification via acylation/sulfonylation/urea formation; also commonly used to tune salt forms/solubility and H-bond networks.
Polar substitution | Amino (derivatization & salt-form window)	6967-12-0	A110323	6-Aminoindazole	≥98%	A 6-position amino supports building diverse amides/ureas/sulfonamides; used to compare activity and ADME changes across substitution sites.
Polar substitution | Nitro (electronic tuning / reducible to amino)	5401-94-5	N107496	5-Nitroindazole	≥98%	Strongly electron-withdrawing; a reducible precursor to 5-amino series; used for electronic and polarity controls.
Polar substitution | Nitro (electronic tuning / reducible to amino)	7597-18-4	N110321	6-Nitroindazole	≥98%	Used for electronic-effect controls or as an intermediate en route to 6-amino series via reduction.
Polar substitution | Hydroxy (H-bonding / solubility tuning)	15579-15-4	H122402	5-Hydroxy-1H-indazole	≥97%	Hydroxy increases polarity and provides H-bonding; can be further etherified/esterified as a prodrug or for side-chain introduction, expanding property space.
Hydrophobic tuning | Methyl (size / conformation / hydrophobicity)	3176-62-3	M176112	3-Methyl-1H-indazole	≥97%	Methyl is a common “fine steric knob”: used for conformation/hydrophobic-pocket occupancy controls to assess benefits of small substituents.
Hydrophobic tuning | Trifluoromethyl (lipophilicity / stability)	57631-05-7	H730035	3-(Trifluoromethyl)-1H-indazole	≥98%	CF₃ is often used to raise lipophilicity and metabolic stability and to alter conformation/pocket occupancy; used as an SAR “hydrophobic knob” control.
Hydrophobic tuning | Trifluoromethyl (lipophilicity / stability)	954239-22-6	H636162	6-(Trifluoromethyl)-1H-indazole	≥97%	6-position CF₃ is often used to enhance lipophilicity and metabolic stability and strengthen hydrophobic-pocket interactions; used for key-site hydrophobic scanning.
Halogenation | Chloro (coupling / position scanning)	29110-74-5	C169319	3-Chloroindazole	≥97%	A 3-position chloro serves as a cross-coupling substrate or a downstream functionalization entry point; commonly used in substitution-pattern scanning for SAR.
Halogenation | Bromo (coupling / position scanning)	40598-94-5	B589034	3-Bromo-1H-indazole	≥95%	A high-frequency coupling intermediate at C-3: used to rapidly build 3-substituted indazole derivatives for SAR and library synthesis.
Halogenation | Iodo (high-reactivity coupling site)	66607-27-0	I177117	3-Iodo-1H-indazole	≥97%	Iodo substitution is often chosen for more facile couplings (e.g., Suzuki); suitable for rapid installation of complex aryl/heteroaryl groups to build series.
Halogenation | Chloro (coupling / position scanning)	13096-96-3	C166913	4-Chloro-1H-indazole	≥97%	Used to build control series with different substitution topologies; often serves as a cross-coupling entry point for position scanning.
Halogenation | Bromo (coupling / position scanning)	186407-74-9	B132684	4-Bromoindazole	≥97%	A common coupling handle to build 4-substituted indazole series for lead optimization and library synthesis.
Halogenation | Fluoro (electronic / metabolic & conformational fine-tuning)	348-26-5	F169766	5-Fluoro-1H-indazole	≥97%	Fluorine is often used for subtle tuning of electronics, metabolic stability, and conformational preference; used for fine SAR and property optimization.
Halogenation | Chloro (coupling / position scanning)	698-26-0	C186101	5-Chloro-1H-indazole	≥97%	A 5-position chloro can be diversified by coupling; also commonly used to compare structure–activity/ADME differences among halogens at the same position.
Halogenation | Bromo (coupling / position scanning)	53857-57-1	B122429	5-Bromo-1H-indazole	≥97%	A standard intermediate for building diverse 5-substituted series; suitable for Suzuki/Buchwald expansions.
Halogenation | Iodo (high-reactivity coupling site)	55919-82-9	I176793	5-Iodo-1H-indazole	≥97%	Enables higher-reactivity coupling at C-5; used to rapidly install larger/more complex substituents to probe hydrophobic pockets and selectivity.
Halogenation | Chloro (coupling / position scanning)	698-25-9	C177222	6-Chloro-1H-indazole	≥97%	A general derivatization entry point at C-6; used in cross-couplings to build 6-substituted series and evaluate position effects.
Halogenation | Bromo (coupling / position scanning)	79762-54-2	B152362	6-Bromoindazole	≥98%	A common cross-coupling site: used in Suzuki / Buchwald–Hartwig to introduce substituents for SAR expansion.
Halogenation | Bromo (coupling / position scanning)	53857-58-2	B122430	7-Bromo-1H-indazole	≥97%	Used to explore less common substitution sites; suitable for “position migration” controls and conformation/selectivity comparisons.

Note: The above are representative Aladdin products. For additional specifications, please refer to the full product list at the end of the article or search the Aladdin website using “product name / CAS / catalog number.”

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