3-Aminocyclopent-2-en-1-one
[CAS# 28566-12-3]

Identification

• Classification: Organic raw materials >> Ketone compound
• Name: 3-Aminocyclopent-2-en-1-one
• Molecular Formula: C₅H₇NO
• Molecular Weight: 97.12
• CAS Registry Number: 28566-12-3
• EC Number: 819-139-0
• SMILES: C1CC(=O)C=C1N

Properties

• Density: 1.2±0.1 g/cm³ Calc.^*
• Boiling point: 199.2±30.0 °C 760 mmHg (Calc.)^*
• Flash point: 74.2±24.6 °C (Calc.)^*
• Index of refraction: 1.539 (Calc.)^*

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H302-H315-H319-H335
• Safety Statements: P261-P264-P264+P265-P270-P271-P280-P301+P317-P302+P352-P304+P340-P305+P351+P338-P319-P321-P330-P332+P317-P337+P317-P362+P364-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Specific target organ toxicity - single exposure	STOT SE	3	H335
Skin irritation	Skin Irrit.	2	H315
Acute toxicity	Acute Tox.	4	H302
Eye irritation	Eye Irrit.	2A	H319

Discovery and Applications

3-Aminocyclopent-2-en-1-one is a small heterocyclic compound consisting of a five-membered cyclopentenone ring substituted with an amino group at the 3-position. The α,β-unsaturated ketone functionality provides a conjugated electrophilic system, while the amino group introduces nucleophilicity and hydrogen-bonding capability. This combination of functional groups makes the compound a versatile intermediate for synthetic organic chemistry, particularly in the construction of nitrogen-containing heterocycles and functionalized cyclic systems.

The synthesis of 3-aminocyclopent-2-en-1-one commonly involves the selective amination of cyclopent-2-en-1-one derivatives. Methods may include nucleophilic substitution, reductive amination of diketone precursors, or Michael addition followed by cyclization, depending on the starting materials and desired stereochemistry. Reaction conditions are carefully controlled to prevent over-reaction or polymerization, and the product is typically isolated as a crystalline or oily solid via recrystallization or chromatographic techniques.

In organic synthesis, 3-aminocyclopent-2-en-1-one is utilized as an intermediate for the preparation of substituted cyclopentenone derivatives, cyclopentane-based heterocycles, and fused ring systems. The α,β-unsaturated ketone allows for conjugate additions, cycloadditions, and condensation reactions, while the amino group can undergo acylation, alkylation, or reductive transformations. This dual reactivity enables stepwise construction of complex molecules with controlled regio- and stereochemistry.

In medicinal chemistry, derivatives of 3-aminocyclopent-2-en-1-one are investigated as potential bioactive agents, including enzyme inhibitors, receptor ligands, and precursors for peptidomimetic compounds. The amino group facilitates hydrogen bonding and interaction with biological targets, while the enone system can act as a Michael acceptor in covalent modification of enzymes or as a scaffold for further functionalization. Such structural features make it useful in the development of small molecule libraries for pharmacological studies.

The compound is also relevant in methodology research. Its combination of an electrophilic conjugated ketone and a nucleophilic amino group allows chemists to explore selective functionalization reactions, asymmetric synthesis, and the development of new synthetic routes to nitrogen-containing heterocycles. It serves as a model compound for studying reactivity patterns in cyclic α,β-unsaturated ketones and for evaluating synthetic strategies for bioactive molecules.

Physically, 3-aminocyclopent-2-en-1-one is generally obtained as a solid or low-melting crystalline compound with moderate solubility in polar organic solvents such as ethanol, methanol, and dimethylformamide. It is stable under standard laboratory conditions but should be protected from strong acids, bases, and oxidizing agents that could react with the amino or enone functionalities. Proper storage ensures its utility for synthetic and medicinal applications.

Overall, 3-aminocyclopent-2-en-1-one is a multifunctional cyclopentenone featuring both a nucleophilic amino group and an electrophilic α,β-unsaturated ketone. Its structural features allow selective chemical transformations and derivatization, making it a valuable intermediate in the synthesis of heterocycles, bioactive molecules, and complex organic targets in medicinal and synthetic chemistry.

References

2019. [3+3] Cyclocondensation of 4,5-Dibenzoyl-1H-pyrrole-2,3-diones with 3-Aminocyclopent-2-enone. Synthesis of Cyclopenta[b]pyridines. Russian Journal of Organic Chemistry, 55(5).
DOI: 10.1134/s1070428019050245

2007. 3-Aminocyclopent-2-en-1-one. Acta Crystallographica Section E, 63(4).
DOI: 10.1107/s1600536807000529