Lysergic acid 2-butylamide

Lysergic acid 2-butylamide (LSB or LASBA), also known as 2-butyllysergamide, is an analogue of LSD originally developed by Richard Pioch at Eli Lilly in the 1950s, 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 It is a structural isomer of LSD, with the two ethyl groups on the amide nitrogen having been replaced by a single sec-butyl group, joined at the 2-position.

Source: Wikipedia — Lysergic acid 2-butylamide (CC BY-SA 4.0)