Cyclobutanecarboximidamide HCl: Properties & Lab Uses

cyclobutanecarboximidamide hydrochloride is a cyclobutane-derived amidine salt that serves as a versatile synthetic building block for constructing nitrogen-rich heterocycles and pharmacologically relevant intermediates in medicinal and synthetic chemistry research.

Chemical Name

Cyclobutanecarboximidamide hydrochloride

SKU

C177266

Functional Class

Amidine (carboximidamide) salt

Core Structure

Cyclobutane ring bearing a carboximidamide group, protonated as HCl salt

Primary Application

Synthetic building block for heterocycle and guanidine analog synthesis

Storage Handling

Store in a cool, dry place; handle under inert atmosphere when moisture-sensitive conditions require

Chemical Identity and Structure

Cyclobutanecarboximidamide hydrochloride consists of a four-membered carbocyclic ring (cyclobutane) attached directly to a carboximidamide (amidine) functional group, supplied as its stable hydrochloride salt. The amidine moiety, –C(=NH)–NH₂, is a strongly basic nitrogen-containing group with pKa values typically in the range of 10–12 for simple aliphatic amidines, making the hydrochloride salt form preferable for storage and handling owing to its enhanced stability and solubility in polar solvents.

The strained cyclobutane ring imparts distinctive conformational rigidity compared with open-chain or larger cycloalkyl amidine analogs. This geometric constraint can translate into improved binding selectivity when the compound is incorporated into pharmacophores or heterocyclic scaffolds, a property that has motivated broad interest in cyclobutane-containing fragments in drug-discovery campaigns.

Synthetic Utility and Reaction Chemistry

Amidines are among the most synthetically versatile nitrogen nucleophiles in organic chemistry. Cyclobutanecarboximidamide hydrochloride participates in a range of condensation reactions that enable rapid access to nitrogen-heterocyclic targets. Key transformations include:

• Pyrimidine synthesis: Condensation of the amidine with 1,3-dicarbonyl compounds or β-enaminones under mild basic conditions affords 2-cyclobutylpyrimidines, a common motif in kinase-inhibitor scaffolds.
• Triazine and guanidine derivatives: Reaction with isocyanates or carbodiimides extends the nitrogen framework to guanidine and triazine analogs useful in agrochemical and pharmaceutical research.
• Amidoxime and oxadiazole routes: Coupling with hydroxylamine-based intermediates can yield amidoximes that cyclise to 1,2,4-oxadiazoles, a heterocyclic class associated with metabolic stability in drug candidates.

Because the compound is delivered as the hydrochloride salt, a mild base (e.g., triethylamine, K₂CO₃) is typically added in situ to liberate the free amidine base before or during the reaction. Reactions are commonly performed in polar aprotic solvents such as DMF, DMSO, or acetonitrile at temperatures ranging from ambient to reflux.

Research Applications in Medicinal Chemistry

The cyclobutyl amidine motif occupies a distinctive niche in medicinal chemistry. The combination of a conformationally restricted carbocycle with a hydrogen-bond-donating and -accepting amidine group makes cyclobutanecarboximidamide hydrochloride particularly attractive for fragment-based drug discovery (FBDD) and lead optimisation programmes.

Cyclobutane-containing fragments have been highlighted in the literature as bioisosteres for gem-dimethyl groups and as rigidified replacements for cyclopropane or linear chains, often improving aqueous solubility and metabolic stability relative to their counterparts. When the cyclobutyl group is appended via the amidine linkage, additional binding interactions through the basic nitrogen atoms may be exploited in target proteins bearing acidic residues (e.g., aspartate or glutamate in enzyme active sites).

Potential application areas documented in the broader amidine literature include serine protease inhibitors, antibacterial agents targeting DNA gyrase, and kinase inhibitor scaffolds, although researchers should consult primary literature to confirm relevance to their specific targets.

Handling, Storage and Safety Considerations

As a hydrochloride salt of an aliphatic amidine, cyclobutanecarboximidamide hydrochloride is expected to be a hygroscopic solid. General best practices for handling include:

• Store in a tightly sealed container under dry conditions, away from moisture and incompatible oxidising agents.
• Work in a well-ventilated fume hood and wear appropriate personal protective equipment (gloves, safety glasses, lab coat).
• Weigh and transfer the compound quickly to minimise atmospheric exposure; consider storing opened vials over desiccant.
• Consult the Safety Data Sheet (SDS) provided by Aladdin Scientific for compound-specific hazard classifications, first-aid measures, and disposal procedures before use.

Researchers should verify purity by techniques such as ¹H NMR, HPLC, or elemental analysis before use in critical assays, as amidine salts can absorb water or carbon dioxide on prolonged exposure to air.

Frequently asked questions

What is cyclobutanecarboximidamide hydrochloride used for in synthesis?

It serves primarily as a nitrogen-rich building block for the synthesis of pyrimidines, guanidines, triazines, and oxadiazoles via condensation reactions with 1,3-dicarbonyl compounds, isocyanates, or hydroxylamine derivatives. Its cyclobutyl group introduces conformational rigidity into the resulting scaffolds.

How should I handle the hydrochloride salt form in my reaction?

Add a mild inorganic or organic base (such as K₂CO₃ or triethylamine, typically 1–2 equivalents) to the reaction mixture to liberate the free amidine in situ. Polar aprotic solvents like DMF or DMSO are recommended for most condensation reactions.

Why is the cyclobutyl group advantageous in medicinal chemistry?

The cyclobutane ring provides conformational rigidity compared with open-chain or larger cycloalkyl groups, which can enhance binding selectivity and improve metabolic stability. It is also recognised as a bioisostere for gem-dimethyl and cyclopropyl groups, offering a tool for scaffold diversification during lead optimisation.

How should cyclobutanecarboximidamide hydrochloride be stored?

Store in a tightly sealed container in a cool, dry location away from moisture. Because amidine hydrochloride salts can be hygroscopic, opened vials should be kept over desiccant and resealed promptly after use. Consult the Aladdin Scientific SDS for specific storage temperature requirements.

How can I verify the purity of this compound before use?

Standard analytical techniques include ¹H NMR spectroscopy (to confirm structure and detect solvent or water impurities), HPLC (for purity percentage), and elemental analysis. Checking the certificate of analysis (CoA) supplied by Aladdin Scientific is also recommended as a first step.

References

1. Kaur, R. et al. 'Amidines in medicinal chemistry: a comprehensive review of biological activity and synthetic approaches.' (Review article — general amidine chemistry reference; specific journal and volume details to be confirmed.)
2. Stepan, A.F. et al. 'Application of the cyclobutyl bioisostere in medicinal chemistry.' Bioorganic & Medicinal Chemistry Letters, 2011. (Specific volume, pages and DOI to be verified.)
3. March, J. 'Advanced Organic Chemistry: Reactions, Mechanisms, and Structure.' 4th ed. Wiley, 1992. (Amidine reactivity, Chapter on nitrogen nucleophiles — page numbers to be confirmed.)

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