3-Amino-3-cyclopropylpropanoic Acid

This compound is typically obtained as a white to off-white crystalline powder. Its molecular formula is C6H11NO2, corresponding to a molecular weight of 129.16. The melting point generally falls within the range of 210–215 °C, often with decomposition evidenced by darkening above 220 °C. The calculated density is approximately 1.21 g/cm³ under ambient conditions. It exhibits moderate solubility in water and polar organic solvents such as methanol and ethanol, while showing limited solubility in acetone and acetonitrile and negligible solubility in non-polar solvents like dichloromethane and hexane. The molecule contains both amino and carboxylic acid functional groups, enabling zwitterion formation and pH-dependent solubility. The cyclopropyl ring introduces significant ring strain and conformational rigidity. Storage in tightly sealed containers protected from light and moisture at reduced temperature (2–8 °C) is recommended to prevent decomposition. Contact with strong oxidizing agents and strong bases should be avoided.

3-Amino-3-cyclopropylpropanoic acid is a non-proteinogenic β-amino acid featuring a cyclopropyl group attached to the carbon bearing the amino functionality. The molecule combines a strained three-membered carbocycle with a β-alanine backbone, creating a rigid, conformationally constrained scaffold. The cyclopropyl ring imparts unique electronic and steric characteristics, influencing both the basicity of the adjacent amine and the overall molecular geometry. The amino and carboxylic acid groups are separated by a two-carbon spacer, allowing for distinct coordination and hydrogen-bonding patterns compared to α-amino acids. The strained ring system can participate in ring-opening reactions under appropriate conditions, providing access to further structural diversity. This combination of a constrained carbocycle with a flexible amino acid backbone makes the compound a valuable building block in medicinal chemistry and peptide mimicry, where conformational restriction can enhance binding selectivity and metabolic stability.

Peptide Mimicry and Drug Design
This cyclopropyl-containing amino acid serves as a constrained surrogate for natural amino acids in peptide-based drug discovery. Incorporation into peptides restricts backbone conformation, potentially enhancing receptor selectivity and resistance to proteolytic degradation. The cyclopropyl group can occupy hydrophobic pockets in target proteins while the amino and carboxylate groups maintain essential hydrogen-bonding interactions.

Building Block for Enzyme Inhibitors
The rigid scaffold is employed in the synthesis of enzyme inhibitors targeting proteases and transferases. The strained ring can be exploited to probe active site geometry and to improve binding affinity through preorganization. Derivatives of this amino acid have been investigated for their potential to inhibit enzymes involved in neurological disorders and metabolic diseases.

Chiral Intermediate in Asymmetric Synthesis
The defined stereochemistry at the amino-bearing carbon makes this compound valuable as a chiral building block for preparing enantiomerically pure pharmaceuticals. After appropriate protection of the amine and carboxylic acid, it can be incorporated into more complex structures through peptide coupling or other transformations, enabling the construction of chiral ligands and organocatalysts.

Neurochemical Research
As a structural analog of inhibitory neurotransmitters, this compound is investigated for its potential to modulate neuronal signaling pathways. The cyclopropyl group may influence interactions with GABA receptors or amino acid transporters, providing insights into structure-activity relationships in the central nervous system and guiding the development of novel therapeutic agents.