(S)-Δ3-THC.(S)-Δ3-tetrahydrocannabinol

(S)-Δ3-THC, also written (S)-Δ6a,10a-THC, carries the double bond of Δ9-THC at the ring junction: the two junction stereocentres disappear, leaving a single stereocentre at C9. Affinity for CB1 is retained: Rosati et al. (2014) measured a Ki of 5 nM at human CB1 for the (S) form, versus 29 nM for the (R) form, and classed the series among partial agonists in [35S]GTPγS assays. In humans, Hollister et al. (1987) observed that the (S) enantiomer produces psychic effects qualitatively comparable to those of Δ9-THC but three to six times less potent, activity residing in this form alone and the combination of both enantiomers not increasing the effect. In pigeons trained to discriminate Δ9-THC, the acetate of the (1S) enantiomer is markedly more potent than that of the (1R) enantiomer (Järbe et al. 1988). For the racemic form, the WHO (2018) notes no mortality in mice at 200 mg/kg intravenously and a potency fifteen times lower than Δ9-THC in seizure-susceptible rabbits. The pharmacokinetics and metabolism of this isomer have not been described.

Source

(S)-Δ3-THC has not been described in hemp and no biosynthetic route is known: it is a laboratory compound. Δ6a,10a-THC, without specification of the enantiomer, has however been identified by the FDA laboratory in THC vaping liquids analysed after the 2019 EVALI outbreak, among "unnatural" isomers attributed to chemical and thermal treatments of the source materials (Ciolino 2021). As achiral chromatographic analyses do not separate the 9R and 9S enantiomers, the share of the (S) form in these products is unknown.

No known enzymatic route. The molecule is obtained by chemical synthesis, from an already optically pure precursor (Srebnik et al. 1984; Rosati et al. 2014).

European Union

Internationally, Δ6a,10a-THC is among the six tetrahydrocannabinol isomers listed by name in Schedule I of the 1971 Convention on Psychotropic Substances, as 7,8,9,10-tetrahydro-6,6,9-trimethyl-3-pentyl-6H-dibenzo[b,d]pyran-1-ol, together with their stereochemical variants: the (S) enantiomer is therefore covered. After its 41st meeting (2018), the WHO Expert Committee on Drug Dependence recommended moving these isomers to Schedule I of the 1961 Convention; the recommendation was not followed and they remain in Schedule I of the 1971 Convention. The European Union keeps no list of its own: each Member State applies the Convention in national law.

France

In France, (S)-Δ3-THC is not listed by name. It falls under the generic entry "Tetrahydrocannabinols, their esters, ethers, salts as well as the salts of the aforementioned derivatives" of the narcotics list (decree of 22 February 1990), an entry moved from annex IV to annex III by the ANSM decision of 6 February 2026. This is a family classification, not an individual listing: production, possession, transfer and use are prohibited, and a consumer product containing it is unlawful, whatever its CBD content.

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

Family

Synthetic CB receptor agonist › Research ligand or medicine

Chemistry

C5 side chain · neutral form

Class

classical

Verification

Every fact on this entry was checked against its primary sources on 20 October 2026.

Wikipedia (English)

Δ3-Tetrahydrocannabinol (new tab)

Article paired by the molecule's structure (InChIKey), revision read on 19 October 2026. Read as a second opinion, never cited as a source.

1. 1Rosati O, Messina F, Pelosi A, Curini M, Petrucci V, Gertsch J, Chicca A. One-pot heterogeneous synthesis of Δ3-tetrahydrocannabinol analogues and xanthenes showing differential binding to CB1 and CB2 receptors. Eur J Med Chem 2014;85:77-86 (new tab)PMID 25072877
2. 2Hollister LE, Gillespie HK, Mechoulam R, Srebnik M. Human pharmacology of 1S and 1R enantiomers of delta-3-tetrahydrocannabinol. Psychopharmacology 1987;92:505-507 (new tab)PMID 2819920
3. 3Järbe TU, Hiltunen AJ, Mechoulam R, Srebnik M, Breuer A. Separation of the discriminative stimulus effects of stereoisomers of Δ2- and Δ3-tetrahydrocannabinols in pigeons. Eur J Pharmacol 1988;156:361-366 (new tab)PMID 2850933
4. 4Consroe P, Martin AR, Fish BS. Use of a potential rabbit model for structure-behavioral activity studies of cannabinoids. J Med Chem 1982;25:596-599 (new tab)PMID 7086846
5. 5WHO, Expert Committee on Drug Dependence. Isomers of THC: Critical Review Report, 41st meeting, 2018 (new tab)
6. 6ECDD Information Repository. Tetrahydrocannabinol (including six isomers): 2019 recommendation and current status (Schedule I, 1971 Convention) (new tab)
7. 7Ciolino LA, Ranieri TL, Brueggemeyer JL, Taylor AM, Mohrhaus AS. EVALI Vaping Liquids Part 1: GC-MS Cannabinoids Profiles and Identification of Unnatural THC Isomers. Front Chem 2021;9:746479 (new tab)PMID 34631667
8. 8ANSM, decision of 6 February 2026 amending the list of substances classified as narcotics and the list of psychotropic substances (new tab)
9. 9ANSM, consolidated list of substances classified as narcotics, updated 16 February 2026 (new tab)
10. 10PubChem CID 71587360, delta3-Tetrahydrocannabinol, (S)- (UNII PYI73UAY3K) (new tab)

SMILES

CCCCCC1=CC2=C(C3=C(CC[C@@H](C3)C)C(O2)(C)C)C(=C1)O

Machine-readable entry (JSON)

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