Muscone

Last updated
Muscone
Muscone Muscone horizontal.svg
Muscone
Muscone 3D ball.png
Names
Preferred IUPAC name
(3R)-3-Methylcyclopentadecan-1-one
Identifiers
3D model (JSmol)
ChEMBL
ChemSpider
ECHA InfoCard 100.007.997 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 208-795-8
PubChem CID
UNII
  • InChI=1S/C16H30O/c1-15-12-10-8-6-4-2-3-5-7-9-11-13-16(17)14-15/h15H,2-14H2,1H3/t15-/m1/s1 X mark.svgN
    Key: ALHUZKCOMYUFRB-OAHLLOKOSA-N X mark.svgN
  • InChI=1/C16H30O/c1-15-12-10-8-6-4-2-3-5-7-9-11-13-16(17)14-15/h15H,2-14H2,1H3/t15-/m1/s1
    Key: ALHUZKCOMYUFRB-OAHLLOKOBX
  • C[C@@H]1CCCCCCCCCCCCC(=O)C1
Properties
C16H30O
Molar mass 238.415 g·mol−1
Density 0.9221 g/cm3
Melting point −15 °C (5 °F; 258 K)
Boiling point 328 °C (622 °F; 601 K)
Hazards
NFPA 704 (fire diamond)
NFPA 704.svgHealth 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineFlammability 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilInstability 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazards (white): no code
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Muscone is a macrocyclic ketone, an organic compound that is the primary contributor to the odor of deer musk. Natural muscone is obtained from musk, a glandular secretion of the musk deer, which has been used in perfumery and medicine for thousands of years. Since obtaining natural musk requires killing the endangered animal, nearly all muscone used in perfumery and for scenting consumer products today is synthetic. It has the characteristic smell of being "musky".

Contents

Chemical structure and synthesis

The chemical structure of muscone was first elucidated by Leopold Ružička. It is a 15-membered ring ketone with one methyl substituent in the 3-position. It is an oily liquid that is found naturally as the (−)-enantiomer, (R)-3-methylcyclopentadecanone. Muscone has been synthesized as the pure (−)-enantiomer as well as the racemate. It is very slightly soluble in water and miscible with alcohol.

One asymmetric synthesis of (−)-muscone begins with commercially available (+)-citronellal, and forms the 15-membered ring via ring-closing metathesis: [1]

Synthesis of muscone via RCM MusconeViaRCM.svg
Synthesis of muscone via RCM

A more recent enantioselective synthesis involves an intramolecular aldol addition/dehydration reaction of a macrocyclic diketone. [2]

Isotopologs

Isotopologs of muscone have been used in a study of the mechanism of olfaction. Global replacement of all hydrogen atoms in muscone was achieved by heating muscone in heavy water (D2O) at 150 °C in the presence of a rhodium on carbon catalyst. [3] It was found that the human musk-recognizing receptor, OR5AN1, identified using a heterologous olfactory receptor expression system and robustly responding to muscone, fails to distinguish between muscone and the so-prepared isotopolog in vitro . [3] OR5AN1 is reported to bind to muscone and related musks such as civetone through hydrogen-bond formation from tyrosine-260 along with hydrophobic interactions with surrounding aromatic residues in the receptor. [4]

References

  1. Kamat, V. P.; Hagiwara, H.; Katsumi, T.; Hoshi, T.; Suzuki, T.; Ando, M. (2000). "Ring Closing Metathesis Directed Synthesis of (R)-(−)-Muscone from (+)-Citronellal". Tetrahedron . 56 (26): 4397–4403. doi:10.1016/S0040-4020(00)00333-1.
  2. Knopff, O.; Kuhne, J.; Fehr, S. (2007). "Enantioselective Intramolecular Aldol Addition/Dehydration Reaction of a Macrocyclic Diketone: Synthesis of the Musk Odorants (R)-Muscone and (R,Z)-5-Muscenone". Angew. Chem. Int. Ed. 46 (8): 1307–1310. doi:10.1002/anie.200604518. PMID   17211908.
  3. 1 2 Block, E.; et al. (2015). "Implausibility of the Vibrational Theory of Olfaction". Proc. Natl. Acad. Sci. USA . 112 (21): E2766 –E2774. Bibcode:2015PNAS..112E2766B. doi: 10.1073/pnas.1503054112 . PMC   4450420 . PMID   25901328.
  4. Ahmed, L.; et al. (2018). "Molecular Mechanism of Activation of Human Musk Receptors OR5AN1 and OR1A1 by (R)-Muscone and Diverse Other Musk-smelling Compounds". Proc. Natl. Acad. Sci. USA. 115 (17): E3950 –E3958. Bibcode:2018PNAS..115E3950A. doi: 10.1073/pnas.1713026115 . PMC   5924878 . PMID   29632183.