RCS-2-butyl.

RCS-2-butyl acts on both receptors of the endocannabinoid system. In the membrane potential assay on AtT-20 cells expressing the human receptors and the GIRK channel, re-read in ChEMBL, it behaves as an agonist with an EC50 of 178 nM at CB1 and 4.5 nM at CB2, a preference of about 40 times for CB2, within the 31 to 42-fold range that Banister et al. (2015) report for the C4 homologues. The potency measured at CB2 therefore clearly exceeds that measured at CB1. The maximal efficacy was not found: it cannot be stated that it behaves as a full agonist of CB1, a property most characterised synthetic cannabinoids share (Fantegrossi et al., 2014, a class-level finding), whereas Δ9-THC is only a partial agonist. No data were found on TRPV1, GPR55, PPARγ or 5-HT1A. Human data are entirely lacking: neither pharmacokinetics, metabolism nor clinical series concern this precise molecule.

Source

An entirely synthetic molecule with no known natural occurrence: it exists neither in hemp nor in any living organism. It belongs to the analogues of the RCS series detected in products intended for human consumption (Banister et al., 2015), and figures in the UNODC list recording the synthetic cannabinoids reported (Zangani et al., 2020). None of this concerns hemp or cannabidiol products.

No biological pathway: this molecule is entirely synthetic, with no plant precursor or enzymatic step. It belongs solely to synthetic chemistry, described here by chemical class only.

European Union

The substance is not listed in the Annex to Council Framework Decision 2004/757/JHA (consolidated version of 12 January 2026), which lists the new psychoactive substances controlled at European Union level; control is a matter for national law. It appears in the UNODC list recording the synthetic cannabinoids reported but not in that of the EUDA (Zangani et al., 2020), which is monitoring and not control. It does not appear in the schedules of the 1971 Convention on Psychotropic Substances (green list of the INCB, 35th and 36th editions). France ties it to a generic definition by chemical family in annex IV of its list (see the French status).

France

RCS-2-butyl is not named in any entry of the ANSM consolidated list (updated 16 February 2026). By its structure, it falls under the generic family of « indol-3-yl methanone » of annex IV, which the text of the decree of 31 March 2017 (JORF of 6 April 2017) already contains: a substituent on the indole nitrogen of the alkyl type (here a butyl) and a group of the phenyl type, substituted or not (here a 2-methoxyphenyl), on the carbon of the methanone bridge. This reading of the structure remains to be confirmed with ANSM. The clause covering tetrahydrocannabinols (annex III since the decision of 6 February 2026) does not apply to this benzoylindole. Outside France, New Zealand named it as a temporary class drug from 16 August 2011 (notice published on 9 August 2011, valid until 16 August 2012 unless renewed).

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

Family

Synthetic CB receptor agonist › New psychoactive substance

Class

benzoylindole

Verification

Classification, sources and binding values checked on 20 October 2026; text read against its sources and Wikipedia.

Wikipedia (English)

No dedicated article.

1. 1Banister SD, Stuart J, Conroy T, Longworth M, Manohar M, Beinat C, Wilkinson SM, Kevin RC, Hibbs DE, Glass M, Connor M, McGregor IS, Kassiou M. Structure-activity relationships of synthetic cannabinoid designer drug RCS-4 and its regioisomers and C4 homologues. Forensic Toxicol. 2015;33:355-366 (abstract read: EC50 CB1 54-574 nM, CB2 4.5-46 nM; C4 homologues 31- to 42-fold selective for CB2) (new tab)DOI 10.1007/s11419-015-0282-9
2. 2ChEMBL, activities of compound CHEMBL4089341 (EC50 CB1 178 nM, CB2 4.5 nM, document CHEMBL4028847) (new tab)
3. 3Spinelli F et al. Perspectives of Cannabinoid Type 2 Receptor (CB2R) Ligands in Neurodegenerative Disorders: Structure-Affinity Relationship (SAfiR) and Structure-Activity Relationship (SAR) Studies. J Med Chem. 2017;60(24):9913-9931 (source document for the values curated by ChEMBL) (new tab)PMID 28608697
4. 4New Zealand Gazette, Temporary Class Drug Notice (Misuse of Drugs Act 1975, s. 4C), published 9 August 2011, in force from 16 August 2011 to 16 August 2012: the 2-methoxy isomer of the butyl analogue of RCS-04 named (new tab)
5. 5Fantegrossi WE, Moran JH, Radominska-Pandya A, Prather PL. Distinct pharmacology and metabolism of K2 synthetic cannabinoids compared to Δ9-THC: mechanism underlying greater toxicity? Life Sci. 2014;97(1):45-54. CLASS datum (full agonism of the synthetic cannabinoids versus partial agonism of THC), not specific to this compound. (new tab)PMID 24084047
6. 6Zangani C et al. The e-Psychonauts' 'Spiced' World: assessment of the synthetic cannabinoids' information available online. Curr Neuropharmacol 2020 ((C4) ORTHO-RCS-4 in the UNODC and NPSFinder lists, absent from the EUDA list) (new tab)PMID 32116194
7. 7ANSM, consolidated list of substances classified as narcotics, updated 16 February 2026 (annex IV, « indol-3-yl methanone » family; RCS-2-butyl not named) (new tab)
8. 8Order of 31 March 2017 amending the order of 22 February 1990: « indol-3-yl methanone » family of annex IV (Légifrance, JORF of 6 April 2017) (new tab)
9. 9PubChem CID 57507910, RCS-2-butyl: identifiers, synonyms (CAS 1345966-63-3), average mass 307.4 (new tab)

SMILES

CCCCN1C=C(C2=CC=CC=C21)C(=O)C3=CC=CC=C3OC

Machine-readable entry (JSON)

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