Lysergic acid 2-butyl amide

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Lysergic acid 2-butyl amide
Systematic (IUPAC) name
CAS Number 137765-82-3 YesY (R,R) isomer, freebase
137765-83-4 (R,R) isomer, maleate salt
PubChem CID: 15119692
ChemSpider 23157987
Synonyms (6aR,9R)- N- (R)- 2-butyl- 7-methyl- 4,6,6a,7,8,9- hexahydroindolo- [4,3-fg] quinoline- 9-carboxamide
Chemical data
Formula C20H25N3O
Molecular mass 323.431 g/mol

Lysergic acid 2-butyl amide (2-Butyllysergamide, LSB) is an analogue of LSD originally developed by Richard Pioch at Eli Lilly in the 1950s,[1] but mostly publicised through research conducted by the team led by David E. Nichols at Purdue University. It is a structural isomer of LSD, with the two ethyl groups on the amide nitrogen having been replaced by a single butyl group, joined at the 2-position.[2] It is one of the few lysergamide derivatives to exceed the potency of LSD in animal drug discrimination assays, with the (R) isomer having an ED50 of 33nmol/kg for producing drug-appropriate responding, vs 48nmol/kg for LSD itself. The corresponding (R)-2-pentyl analogue has higher binding affinity for the 5-HT1A and 5-HT2A receptors, but is less potent in producing drug-appropriate responding, suggesting that the butyl compound has a higher efficacy at the receptor target.[3] The drug discrimination assay for LSD in rats involves both 5-HT1A and 5-HT2A mediated components, and while lysergic acid 2-butyl amide is more potent than LSD as a 5-HT1A agonist, it is slightly less potent as a 5-HT2A agonist, and so would probably be slightly less potent than LSD as a hallucinogen in humans. The main use for this drug has been in studies of the binding site at the 5-HT2A receptor through which LSD exerts most of its pharmacological effects,[4] with the stereoselective activity of these unsymmetric monoalkyl lysergamides foreshadowing the subsequent development of compounds such as lysergic acid 2,4-dimethylazetidide (LSZ).

See also


  1. US patent 2997470, Richard P. Pioch, "LYSERGIC ACID AMIDES", published 1956-03-05, issued 1961-08-22 
  2. Oberlender R, Pfaff RC, Johnson MP, Huang XM, Nichols DE. Stereoselective LSD-like activity in d-lysergic acid amides of (R)- and (S)-2-aminobutane. Journal of Medicinal Chemistry. 1992 Jan 24;35(2):203-11. PMID 1732537
  3. Monte AP, Marona-Lewicka D, Kanthasamy A, Sanders-Bush E, Nichols DE. Stereoselective LSD-like activity in a series of d-lysergic acid amides of (R)- and (S)-2-aminoalkanes. Journal of Medicinal Chemistry. 1995 Mar 17;38(6):958-66. doi:10.1021/jm00006a015 PMID 7699712
  4. David E. Nichols. LSD and Its Lysergamide Cousins. The Heffter Review of Psychedelic Research. 2001;2:80-87.