5-Methyl-1-(2,2,3-trimethyl-3-cyclopenten-1-yl)-6-oxabicyclo[3.2.1]octane (CAS 139539-66-5) — Woody Base Note Fragrance Ingredient

Woody · Balsamic

5-Methyl-1-(2,2,3-trimethyl-3-cyclopenten-1-yl)-6-oxabicyclo[3.2.1]octane

CAS 139539-66-5

Origin
synthetic
Note
Base
IFRA
Generally safe
Data as of: Apr 2026

What Is 5-Methyl-1-(2,2,3-trimethyl-3-cyclopenten-1-yl)-6-oxabicyclo[3.2.1]octane?

5-Methyl-1-(2,2,3-trimethyl-3-cyclopenten-1-yl)-6-oxabicyclo[3.2.1]octane is a synthetic fragrance ingredient used in perfumery. It’s found in some modern woody and amber fragrances. This molecule contributes to complex scent profiles, often adding depth and longevity to fragrance compositions.

Safety Profile

GENERALLY SAFE
Generally safeUse with awarenessProfessional use
No major safety concerns reported
Limited toxicological data available
CAS
139539-66-5
Formula
Mixture
MW
Variable
Odor Family
Woody · Balsamic
Layer 1 · Enthusiast

What Does 5-Methyl-1-(2,2,3-trimethyl-3-cyclopenten-1-yl)-6-oxabicyclo[3.2.1]octane Smell Like?

This synthetic molecule offers a complex woody-amber character with subtle spicy undertones. It evolves from an initial crisp, slightly camphoraceous opening to a warm, resinous heart. The dry-down reveals a sophisticated woody-amber base with excellent tenacity. The scent profile bridges woody and amber accords, making it versatile in modern fragrance design.

Scent Profile
Layer 2

2D Molecular Structure

5-Methyl-1-(2,2,3-trimethylcyclopent-3-en-1-yl)-6-oxabicyclo[3.2.1]octane

SMILES: CC1=CCC(C23COC(C)(C2)CCC3)C1(C)C

Chemistry, Properties & Perfumer Guide

The Chemistry

5-Methyl-1-(2,2,3-trimethyl-3-cyclopenten-1-yl)-6-oxabicyclo[3.2.1]octane is a synthetic bicyclic ether with a complex molecular structure. The molecule combines cyclopentene and oxabicyclooctane moieties, creating unique stereochemical properties. Synthesis typically involves multi-step organic reactions including cyclization and ether formation. The stereochemistry significantly impacts its odor profile, with different stereoisomers potentially exhibiting varying scent characteristics.

Physical & Chemical Properties

Perfumer Guide

Note Position
Base
Volatility
Low (8+ hours)
Blending
Good
ApplicationTypical %RangeNotes
Fine Fragrance1-3%Up to 5%Base note modifier
Functional Fragrance0.1-0.5%Up to 1%Background note

Classic Accords

Tip: Use in small quantities to add depth to woody-amber bases without overwhelming the composition.

Alternatives & Comparisons

1
Ambroxan CAS 6790-58-5

A more widely used amber material with similar longevity but different odor profile.

2
Norlimbanol CAS 70788-30-6

Offers a more pronounced woody character with similar structural complexity.

Layer 3

Safety, Regulatory & Sustainability

⚠ Regulatory Disclaimer

General reference only. Consult current IFRA Standards Library before formulating.

IFRA Status

No IFRA restrictions currently apply to this material.

RIFM Assessment

No RIFM assessment currently available for this material.

Sustainability

As a synthetic material, this compound is produced through controlled chemical processes without natural resource depletion concerns. However, like all synthetic materials, its environmental impact depends on manufacturing processes and waste management. The complex synthesis may require multiple steps with associated energy inputs.

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References

    Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.

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    Physicochemical Properties

    DTXSID: DTXSID101021305

    Physical Properties

    Molecular Weight 234.383 g/mol🔬 EPA CompTox
    Density 0.972 g/cm^3📊 OPERA
    Boiling Point 285.939 °C📊 OPERA
    Melting Point 81.333 °C📊 OPERA
    Flash Point 123.135 °C📊 OPERA
    Refractive Index 1.516 Dimensionless📊 OPERA
    Molar Volume 235.56 cm^3/mol📊 OPERA

    Partition & Solubility

    LogP (Octanol-Water) 5.068 Log10 unitless📊 OPERA
    LogD (pH 5.5) 5.068 Log10 unitless📊 OPERA
    LogD (pH 7.4) 5.068 Log10 unitless📊 OPERA
    LogKoa (Octanol-Air) 7.45 Log10 unitless📊 OPERA
    Water Solubility 0 mol/L📊 OPERA
    Henry's Law Constant 0 atm-m3/mole📊 OPERA

    Transport Properties

    Vapor Pressure 0.01 mmHg📊 OPERA
    Surface Tension 32.971 dyn/cm📊 OPERA
    Thermal Conductivity 111.837 mW/(m*K)📊 OPERA

    Molecular Descriptors

    Topological Polar Surface Area 9.23 Ų💻 Computed
    H-Bond Donors 0 count💻 Computed
    H-Bond Acceptors 1 count💻 Computed
    Rotatable Bonds 1 count💻 Computed
    Aromatic Rings 0 count💻 Computed
    Molar Refractivity 71.181 cm^3/mol📊 OPERA
    Polarizability 28.218 Å^3📊 OPERA

    Data Sources:

    🔬 EPA Experimental data from U.S. EPA CompTox Chemicals Dashboard & CTX APIs. 📊 OPERA Predicted using EPA's OPERA QSAR models. 💻 Computed Calculated from SMILES using RDKit.

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