L-Iso-LSD

l-Iso-LSD, also known as (–)-iso-LSD or (5S,8R)-iso-LSD, as well as l-isolysergic acid diethylamide, is a lysergamide and one of four possible stereoisomers of the lysergic acid diethylamide (LSD) molecule (with the psychedelic drug actually being the enantiopure d-isomer).^[1][2]

For other uses, see LSD (disambiguation) and Lysergic acid diethylamide (disambiguation).

l-Iso-LSD

Clinical data
Other names	(–)-Iso-LSD; (5S,8R)-Iso-LSD; levo-Iso-LSD; l-Isolysergic acid diethylamide; N,N-Diethyl-6-methyl-9,10-didehydro-5α-ergoline-8β-carboxamide
ATC code	None
Identifiers
IUPAC name (6aS,9R)-N,N-Diethyl-7-methyl-4,6,6a,7,8,9-hexahydroindolo[4,3-fg]quinoline-9-carboxamide
PubChem CID	56841613
ChemSpider	32809688
Chemical and physical data
Formula	C20H25N3O
Molar mass	323.440 g·mol−1
3D model (JSmol)	Interactive image
SMILES CCN(CC)C(=O)[C@H]1CN([C@H]2CC3=CNC4=CC=CC(=C34)C2=C1)C
InChI InChI=1S/C20H25N3O/c1-4-23(5-2)20(24)14-9-16-15-7-6-8-17-19(15)13(11-21-17)10-18(16)22(3)12-14/h6-9,11,14,18,21H,4-5,10,12H2,1-3H3/t14-,18+/m1/s1 Key:VAYOSLLFUXYJDT-KDOFPFPSSA-N

The LSD molecule has two chiral centers at carbons 5 and 8 of the ergoline ring system and hence there are four possible enantiomeric stereoisomers of LSD.^[2][3] l-Iso-LSD, also known as (–)-iso-LSD or (5S,8R)-iso-LSD, is one of four possible stereoisomers.^[2][3] The other isomers are LSD (d-LSD, (+)-LSD, or (5R,8R)-LSD), iso-LSD (d-iso-LSD, (+)-iso-LSD, or (5R-8S)-LSD), and l-LSD ((–)-LSD or (5S,8S)-LSD).^[2][3] None of them are known to have significant psychoactivity in humans besides LSD.^[2][3][4]

l-Iso-LSD showed only 0.1% of the antiserotonergic activity of LSD in the isolated rat uterus.^[5] Hence, it was about 1,000-fold less potent than LSD in this assay and was regarded as essentially inactive.^[5]

l-Iso-LSD showed no psychedelic effects in humans at a dose of up to 500 μg orally or up to 20 times the minimum effective dose of LSD (~25 μg).^{[6][7][8][4][1]} According to Albert Hofmann, the only effect of l-iso-LSD at a dose of 500 μg was mild nausea.^[4]

l-Iso-LSD was first described in the scientific literature by at least the 1950s.^[5][7][4]

Chemical structures of LSD and its three stereoisomers, including l-iso-LSD ((–)-iso-LSD).

See also

• Substituted lysergamide