OTHC.10-oxo-Δ6a(10a)-tetrahydrocannabinol

10-Oxo-Δ6a(10a)-tetrahydrocannabinol (OTHC) was isolated in 1975 by Friedrich-Fiechtl and Spiteller from Afghan hashish, together with cannabifuran, dehydrocannabifuran and cannabichromanone; Radwan et al. (2021) place it among the « miscellaneous » cannabinoids. Its skeleton is that of THC, with a 6a(10a) double bond and a ketone at 10; it has a single stereocentre, at 9. Its origin, enzymatic or by degradation, is established by no source. A profiling study of a heated cannabis extract (Lewis 2017) only proposed it among several candidates for a mass signal, without identification. No affinity, activity, pharmacokinetic or toxicity measurement was found.

Source

Isolated from Afghan hashish (1975); origin not established

No formation pathway, enzymatic or not, has been established. No source consulted demonstrates that it derives from the oxidation of Δ9-THC.

European Union

No EU instrument specific to the molecule. Not named in the schedules of the 1961 and 1971 United Nations conventions, according to annexes I to III of the ANSM consolidated list (26/06/2026). Checked 20/10/2026.

France

OTHC is not named in the ANSM consolidated list (updated 26/06/2026). It is a derivative of the benzo[c]chromene nucleus carrying the substituents listed in the generic class of the ANSM decisions of 22/05/2024 and 03/06/2024 (hydroxyl at 1, pentyl chain at 3, two methyls at 6, methyl at 9), but also a ketone at 10, which the definition does not mention; it is not among the exclusions (CBN, CBNA, THCV and THCVA up to 0.3 %, THCA subject to content). Whether it falls within the class, and whether it could come under the entry « Tétrahydrocannabinols, leurs esters, éthers, sels » (annex III since the ANSM decision of 06/02/2026), are matters of legal interpretation. Checked 20/10/2026.

Sources: EUR-Lex, UNODC, CND, ANSM, IUPHAR/BPS, ChEBI, EUDA. Our method.

Family

Phytocannabinoid › Minor

Presence in the plant

Present in the plant; origin not established

Chemistry

Miscellaneous · C5 side chain · neutral form

Verification

Checked on 20 October 2026; some points still await human review.

Wikipedia (English)

No dedicated article.

1. 1Friedrich-Fiechtl & Spiteller 1975, Tetrahedron 31:479: « Neue Cannabinoide 1 » (isolation of OTHC) (new tab)DOI 10.1016/0040-4020(75)85016-2
2. 2Radwan et al. 2021, Molecules: « miscellaneous » cannabinoids (new tab)PMID 34066753
3. 3Lewis et al. 2017, ACS Omega: profiling of cannabis extracts (m/z 329.43 signal) (new tab)PMID 30023762
4. 4GSRS, UNII R3W5M56QFX: OTHC (racemic, CAS 56154-60-0, PubChem 59444418) (new tab)
5. 5ANSM, consolidated list of narcotics, updated 26/06/2026 (benzo[c]chromene class; annex III) (new tab)

SMILES

CCCCCC1=CC(=C2C(=C1)OC(C3=C2C(=O)C(CC3)C)(C)C)O

Machine-readable entry (JSON)

LLM ingestion format: a structured superset of the entry (identifiers, binding, versioned legal status). Full corpus.