cis-3-Hydroxy-3-methylcyclobutanecarboxylic Acid: Lab Guide

cis-3-hydroxy-3-methylcyclobutanecarboxylic acid is a strained, bifunctional small-molecule building block featuring a cis-configured tertiary hydroxyl and a carboxylic acid on a cyclobutane ring, making it a versatile intermediate in medicinal chemistry and pharmaceutical synthesis.

Chemical Name

cis-3-hydroxy-3-methylcyclobutanecarboxylic acid

SKU

C173793

Molecular Formula

C6H10O3

Molecular Weight

130.14 g/mol

Key Functional Groups

Tertiary hydroxyl (–OH) and carboxylic acid (–COOH) on a cyclobutane ring

Stereochemistry

cis configuration at C-1 and C-3 positions

Chemical Identity and Structural Features

cis-3-Hydroxy-3-methylcyclobutanecarboxylic acid (SKU: C173793) belongs to the class of cyclobutane carboxylic acids—four-membered carbocyclic compounds prized in contemporary drug discovery for their ability to impart three-dimensionality and metabolic stability to candidate molecules. The compound carries two reactive handles: a tertiary alcohol at C-3 and a carboxylic acid at C-1, both oriented in a cis (same-face) relationship across the cyclobutane ring.

The rigid, strained ring system enforces a well-defined spatial relationship between the two functional groups, a property exploited by medicinal chemists to replace flat, aromatic fragments with sp³-rich bioisosteres. The methyl substituent at C-3 renders the hydroxyl group tertiary, reducing its susceptibility to oxidative metabolism relative to secondary or primary alcohols while maintaining hydrogen-bond-donor capacity.

Molecular formula: C₆H₁₀O₃; molecular weight: 130.14 g/mol. The compound is typically supplied as a white to off-white crystalline solid.

Recommended Handling, Storage and Safety

Storage: Store the compound in a tightly sealed container under cool, dry conditions, typically at 2–8 °C or as specified on the certificate of analysis (CoA). Protect from moisture and prolonged exposure to light. When stored correctly, the reagent is expected to remain stable for at least 12 months from the date of receipt; always verify the expiry date on the CoA.

Handling: Use standard laboratory personal protective equipment (PPE): lab coat, nitrile gloves and safety glasses. Although cis-3-hydroxy-3-methylcyclobutanecarboxylic acid is not classified as a highly hazardous material, carboxylic acids can be irritating to skin, eyes and mucous membranes. Handling should be performed in a well-ventilated area or fume hood when working with fine powders to avoid inhalation.

Solubility guidance: The compound is generally soluble in polar aprotic solvents such as DMSO and DMF, and in alcohols (methanol, ethanol). Aqueous solubility is moderate to good under basic conditions due to carboxylate formation; adjust pH accordingly when preparing stock solutions for biological assays.

Disposal: Dispose of waste in accordance with local institutional and governmental regulations for organic chemical waste. Do not pour down drains without appropriate treatment.

Applications in Synthesis and Drug Discovery

cis-3-Hydroxy-3-methylcyclobutanecarboxylic acid is primarily employed as a bifunctional building block in the synthesis of pharmaceuticals, agrochemicals and specialty materials. Its value derives from two intersecting trends in modern medicinal chemistry:

• Escape from flatland: Replacing aromatic rings with saturated, sp³-rich cyclobutane units improves aqueous solubility, reduces promiscuous binding and enhances selectivity profiles of drug candidates.
• Bioisosteric applications: The cyclobutane core can serve as a rigid linker or a bioisostere for gem-dimethyl groups, cyclopropane or piperidine rings, offering distinct conformational and pharmacokinetic advantages.

Synthetic chemists exploit the carboxylic acid group for standard transformations including amide bond formation (coupling with amines using EDC/HOBt, HATU or similar reagents), esterification, and conversion to acyl chlorides or mixed anhydrides. The tertiary hydroxyl group can participate in etherification, esterification or serve as a directing group in ring-opening reactions. The cis stereochemistry constrains the dihedral angle between substituents, which can be critical for target engagement in structure-activity relationship (SAR) studies.

This compound is of particular relevance to programs targeting CNS disorders, kinase inhibition and GPCR modulation, where constrained, three-dimensional scaffolds frequently demonstrate improved CNS penetration and reduced CYP liability compared to their planar counterparts.

Purity Specifications and Quality Assurance

Research-grade cis-3-hydroxy-3-methylcyclobutanecarboxylic acid supplied by Aladdin Scientific (SKU: C173793) is accompanied by a Certificate of Analysis (CoA) detailing lot-specific quality data. Key parameters typically assessed include:

• Purity: Determined by HPLC or GC; research-grade material is generally ≥95% pure. Confirm the exact specification on the lot CoA before use in quantitative assays.
• Identity: Confirmed by ¹H NMR, ¹³C NMR and/or high-resolution mass spectrometry (HRMS). The cis stereochemical assignment is verified by NMR coupling constant analysis or X-ray crystallography at the manufacturing stage.
• Water content: Assessed by Karl Fischer titration where applicable; residual moisture can affect accurate weighing and solution preparation.
• Appearance: White to off-white crystalline powder or solid.

Before preparing solutions for biological screening, researchers should confirm purity by independent analytical methods (e.g., LC-MS or qNMR) to ensure data integrity. Lot-to-lot consistency should be monitored in long-running assay campaigns by retesting against an in-house reference standard.

Practical Tips for Solution Preparation and Assay Use

Stock solution preparation: Weigh the required amount of solid on a calibrated analytical balance inside a low-humidity environment. Dissolve in DMSO to prepare a concentrated stock (e.g., 10–100 mM); vortex and sonicate briefly if necessary. For aqueous stocks, dissolve in a minimum volume of 0.1 M NaOH, then dilute with phosphate-buffered saline (PBS) to the target concentration and adjust pH to 7.4.

Freeze-thaw cycles: Minimize freeze-thaw cycles of DMSO stock solutions. Aliquot into single-use volumes upon preparation to preserve compound integrity over time.

Compatibility: The carboxylic acid functionality may react with primary amines in certain buffer systems (e.g., Tris-HCl) at elevated temperatures over extended periods. Prefer PBS or HEPES buffers for long-term incubations.

Reaction monitoring: When used as a synthetic substrate, monitor reaction progress by TLC (UV or KMnO₄ staining) or LC-MS. The carboxylic acid proton appears around δ 10–12 ppm in ¹H NMR (DMSO-d₆); the tertiary C–OH carbon resonates near δ 70–72 ppm in ¹³C NMR.

Coupling reactions: For amide bond formation, activate the carboxylic acid with HATU (1.1 equiv) and DIPEA (2–3 equiv) in DMF at room temperature before addition of the amine coupling partner. Monitor for racemization or epimerization at stereocenters during prolonged activation steps.

Frequently asked questions

What is the recommended storage condition for cis-3-hydroxy-3-methylcyclobutanecarboxylic acid?

Store the compound in a tightly sealed container at 2–8 °C in a cool, dry location away from moisture and light. Under these conditions the reagent is expected to be stable for at least 12 months from receipt; always consult the lot-specific Certificate of Analysis for the confirmed expiry date.

Which solvents are most suitable for dissolving cis-3-hydroxy-3-methylcyclobutanecarboxylic acid?

DMSO and DMF are the preferred solvents for preparing concentrated stock solutions. The compound also dissolves readily in alcohols such as methanol and ethanol. For aqueous applications, dissolve first in dilute NaOH and then dilute with PBS, adjusting to pH 7.4 before use in biological assays.

How is the cis stereochemistry of this compound verified?

The cis configuration is confirmed during manufacture by NMR spectroscopy—specifically through analysis of vicinal coupling constants and NOE correlations—and in some cases by single-crystal X-ray diffraction. End-users can verify identity and stereochemical purity using ¹H NMR and, where required, chiral HPLC or vibrational circular dichroism (VCD).

What coupling reagents are compatible with the carboxylic acid group for amide synthesis?

Commonly used coupling reagents compatible with this substrate include HATU, HBTU, EDC/HOBt and T3P. HATU with DIPEA in DMF at room temperature is a widely adopted protocol offering high efficiency and mild conditions. Always monitor for potential epimerization at stereocenters during extended activation steps.

Is cis-3-hydroxy-3-methylcyclobutanecarboxylic acid suitable as a bioisostere in drug design?

Yes. The cyclobutane scaffold with its cis-disposed hydroxyl and carboxylic acid groups is widely used as a three-dimensional bioisostere to replace flat aromatic rings or gem-dimethyl motifs in drug candidates, improving aqueous solubility, metabolic stability and selectivity. It is particularly relevant in CNS, kinase and GPCR-targeted drug discovery programs.

References

1. Lovering F, Bikker J, Humblet C. Escape from flatland: increasing saturation as an approach to improving clinical success. J Med Chem. 2009;52(21):6752-6756. doi:10.1021/jm901241e
2. Aldeghi M, Gapsys V, de Groot BL. Accurate estimation of ligand binding affinity changes upon protein mutation. ACS Cent Sci. 2018;4(12):1708-1718. doi:10.1021/acscentsci.8b00717
3. Stepan AF et al. Application of the bicyclo[1.1.1]pentane motif as a nonclassical phenyl bioisostere in the design of a potent and orally active γ-secretase inhibitor. J Med Chem. 2012;55(7):3414-3424. doi:10.1021/jm300037v

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