What molecule am I?
2-Hydroxy-3-methyl-2-cyclopenten-1-one (HMCP) is a cyclic ketone-aldehyde that has been known since 1926, when C. A. Rojahn and Ferdinande Rühl at the Technical University of Braunschweig (Germany) isolated it from wood vinegar1. At the time, the molecule was known as methylcyclopentenolone.
HMCP is a tautomer of 3-methyl-1,2-cyclopentanedione2, in which the hydroxyl hydrogen of HMCP is shifted to the ring double bond to form a diketone. HMCP is the more thermodynamically favored compound; the two have the same melting and boiling points.
HMCP is one of the dozens of flavor components of maple syrup, as described by David W. Ball at Cleveland State University in 2007. On its own, HMCP has an aroma and taste that remind people of maple syrup or caramel. The synthetic commercial product is used as a food flavoring and perfume component, often under the name cyclotene.
HMCP is also widely known as “maple lactone” even though it does not contain the lactone structure.
1. Produced from the destructive distillation of wood; contains ≈10% acetic acid.
2. CAS Reg. No. 765-70-8.
2-Hydroxy-3-methyl-2-cyclopenten-1-one hazard information
| Hazard class* | GHS code and hazard statement | |
|---|---|---|
| Acute toxicity, oral, category 4 | H302—Harmful if swallowed |  |
| Skin sensitization, category 1 | H317—May cause an allergic skin reaction | |
| Serious eye damage, category 1 | H318—Causes serious eye damage |  |
| Short-term (acute) aquatic hazard, category 3 | H402—Harmful to aquatic life | |
*Globally Harmonized System (GHS) of Classification and Labeling of Chemicals. Explanation of pictograms.
Atumelnant1, originally called CRN04894, is a nonpeptide melanocortin type 2 receptor antagonist that suppresses adrenocorticotrophic hormone (ACTH)-stimulated corticosterone secretion. In March of this year, Sun Hee Kim and co-workers at Crinetics Pharmaceuticals (San Diego) reported its development to combat ACTH-dependent endocrine diseases such as congenital adrenal hyperplasia and Cushing’s disease.
The Crinetics website lists the company’s preclinical, Phase 1, and Phase 2 studies from 2019 through 2024. On December 9, the company announced that the US Food and Drug Administration accepted its new drug application for another developmental drug, paltusotine2, a selective somatostatin receptor type 2 agonist for treating acromegaly and neuroendocrine tumors.
1. CAS Reg. No. 2392970-97-5; SciFindern name: 2-pyridinecarboxamide, N-(3S)-1-azabicyclo[2.2.2]oct-3-yl-6-(2-ethoxyphenyl)-3-[(2R)-2-ethyl-4-{[1-(trifluoromethyl)cyclobutyl]carbonyl}-1-piperazinyl]-.
2. CAS Reg. No. 2172870-89-0.
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2-Hydroxy-3-methyl-2-cyclopenten-1-one fast facts
| CAS Reg. No. | 80-71-7 |
| SciFindern name | 2-Cyclopenten-1-one, 2-hydroxy-3-methyl- |
| Empirical formula | C6H8O2 |
| Molar mass | 112.13 g/mol |
| Appearance | White to light yellow crystals or powder |
| Melting point | 105–108 °C |
| Boiling point | 179 °C |
| Water solubility | ≈14 g/L |
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