4-Iodo-1-methyl-1H-pyrazole-5-carbaldehyde: Properties & Uses
4-Iodo-1-methyl-1H-pyrazole-5-carbaldehyde: Properties & Uses
4-Iodo-1-methyl-1H-pyrazole-5-carbaldehyde is a halogenated, N-methylated pyrazole aldehyde that serves as a versatile bifunctional building block in medicinal chemistry and synthetic organic chemistry, offering orthogonal reactive handles—an aryl iodide and an aldehyde—on a five-membered nitrogen-containing heterocyclic scaffold.
- Chemical Name
- 4-Iodo-1-methyl-1H-pyrazole-5-carbaldehyde
- SKU / Catalog Number
- I729084
- Molecular Formula
- C5H5IN2O
- Molecular Weight
- 236.01 g/mol
- Core Scaffold
- 1-Methylpyrazole with C-4 iodo and C-5 formyl substituents
- Key Functional Groups
- Aryl iodide (C–I), aldehyde (–CHO), N-methyl pyrazole
- Primary Application
- Bifunctional building block for cross-coupling and condensation reactions in drug discovery
Chemical Structure and Key Physicochemical Properties
4-Iodo-1-methyl-1H-pyrazole-5-carbaldehyde (molecular formula C5H5IN2O; MW 236.01 g/mol) belongs to the class of halogenated pyrazole carbaldehydes. The compound features a five-membered aromatic pyrazole ring bearing an N-methyl group at position 1, an iodo substituent at position 4, and a formyl (–CHO) group at position 5. This substitution pattern places two orthogonal electrophilic handles in close proximity on the heterocyclic ring.
The aryl C–I bond is appreciably weaker than C–Br or C–Cl bonds, rendering it highly reactive toward oxidative addition into palladium(0) and other transition-metal catalysts. The aldehyde at the 5-position is activated by the adjacent electron-withdrawing effect of the ring nitrogen atoms, making it susceptible to nucleophilic addition, reductive amination, and condensation reactions. Together these features make the compound a compact, bifunctional reagent well suited for sequential or one-pot multi-step transformations.
The molecule is expected to be a crystalline solid at room temperature. Storage under inert atmosphere at low temperature (2–8 °C) is recommended to prevent oxidation of the aldehyde and to preserve the integrity of the C–I bond over time.
Synthetic Applications and Role as a Building Block
The dual functionality of 4-Iodo-1-methyl-1H-pyrazole-5-carbaldehyde makes it a powerful intermediate in modern synthetic chemistry. The C-4 aryl iodide is an ideal partner for palladium-catalyzed cross-coupling reactions, including Suzuki–Miyaura, Sonogashira, Heck, and Negishi couplings. These transformations allow researchers to install diverse aryl, vinyl, or alkynyl groups at the 4-position while retaining the aldehyde intact for subsequent elaboration.
The C-5 aldehyde, in turn, can undergo a wide range of transformations: reductive amination to give aminomethyl derivatives, Wittig or Horner–Wadsworth–Emmons olefination to furnish vinyl-extended scaffolds, condensation with hydrazines or hydroxylamines to produce hydrazones or oximes, and nucleophilic addition of organometallic reagents to yield secondary alcohols. The combination of these two reactivity vectors allows medicinal chemists to rapidly build molecular complexity from this single starting material.
Pyrazole-containing compounds are well represented in approved pharmaceuticals and agrochemicals, and N-methyl pyrazole aldehydes such as this compound are routinely employed as fragments in drug-discovery programs targeting kinases, GPCRs, and other therapeutic targets. The iodo handle additionally supports radioiodination strategies for imaging-probe development when isotopically labeled iodine is used.
Handling, Storage, and Safety Considerations
As with all organoiodo compounds, 4-Iodo-1-methyl-1H-pyrazole-5-carbaldehyde should be handled with appropriate personal protective equipment, including nitrile gloves, safety glasses, and a laboratory coat. Work should be performed in a well-ventilated fume hood to avoid inhalation of dust or vapors. Aldehydes can be irritating to the respiratory tract and mucous membranes.
For storage, keep the compound tightly sealed under an inert atmosphere (nitrogen or argon) at 2–8 °C, away from light and moisture. Prolonged exposure to air may lead to slow oxidation of the aldehyde to the corresponding carboxylic acid, and moisture can promote hydration of the carbonyl. Under recommended storage conditions, the material is expected to remain stable for an extended period; however, purity should be verified by analytical methods (e.g., 1H NMR, HPLC) before use in sensitive applications.
Dispose of waste in accordance with local and institutional regulations governing organohalogen compounds. Refer to the Safety Data Sheet (SDS) provided by Aladdin Scientific for complete hazard information, first-aid measures, and disposal guidance.
Ordering Information and Quality Assurance
4-Iodo-1-methyl-1H-pyrazole-5-carbaldehyde is available from Aladdin Scientific under catalog number I729084. Aladdin Scientific is committed to providing research-grade reagents supported by quality control documentation. Each lot is subject to characterization to confirm identity and purity prior to release.
Researchers requiring specific purity grades, custom pack sizes, or bulk quantities are encouraged to contact Aladdin Scientific's technical sales team. Certificate of Analysis (CoA) documents and Safety Data Sheets (SDS) are available on request or through the product page on the Aladdin Scientific website.
For procurement teams, Aladdin Scientific supports institutional purchase orders, online ordering, and a range of payment and shipping options to streamline the acquisition of specialty heterocyclic reagents. Reward points and promotional pricing may be available; consult the website for current offers.
Frequently asked questions
What makes 4-Iodo-1-methyl-1H-pyrazole-5-carbaldehyde useful as a synthetic building block?
The compound carries two orthogonal reactive handles on the same pyrazole ring: an aryl iodide at C-4 that is highly reactive in palladium-catalyzed cross-coupling reactions, and an aldehyde at C-5 amenable to condensation, reductive amination, and nucleophilic addition. This bifunctionality enables sequential diversification from a single scaffold, making it especially valuable in medicinal chemistry and fragment-based drug discovery.
How should 4-Iodo-1-methyl-1H-pyrazole-5-carbaldehyde be stored to maintain stability?
The compound should be stored tightly sealed under an inert atmosphere (nitrogen or argon) at 2–8 °C, protected from light and moisture. These precautions minimize oxidation of the aldehyde functional group and degradation of the carbon–iodine bond, preserving reagent quality over time.
Which cross-coupling reactions are compatible with the aryl iodide in this compound?
The C-4 aryl iodide is compatible with a broad range of palladium-catalyzed cross-coupling protocols, including Suzuki–Miyaura (with arylboronic acids), Sonogashira (with terminal alkynes), Heck (with alkenes), and Negishi (with organozinc reagents) couplings. The high reactivity of aryl iodides toward oxidative addition typically allows the use of mild conditions and a wide selection of ligands and catalyst systems.
How can I verify the purity of 4-Iodo-1-methyl-1H-pyrazole-5-carbaldehyde before use?
Purity can be assessed by standard analytical techniques such as proton NMR spectroscopy (checking for the characteristic aldehyde proton signal near δ 10 ppm and the pyrazole ring proton) and HPLC with UV detection. A Certificate of Analysis (CoA) for each lot is available from Aladdin Scientific and provides lot-specific quality data.
References
- General reference on palladium-catalyzed cross-coupling reactions of aryl iodides: Miyaura, N.; Suzuki, A. Chem. Rev. 1995, 95, 2457–2483. doi:10.1021/cr00039a007
- General reference on pyrazole-containing pharmaceuticals and their synthetic routes: Textbook-level knowledge; no specific citation available from source material.
- Sonogashira, K. et al. Tetrahedron Lett. 1975, 16, 4467–4470. (Sonogashira coupling of aryl halides with terminal alkynes.)
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