4-Desmethylene-LSD
4-Desmethylene-LSD, also known as 4-nor-LSD, 3,5-seco-LSD, or DEIMDHPCA, is an indole derivative and a "partial" or simplified lysergamide which is closely related to the highly potent serotonergic psychedelic lysergic acid diethylamide (LSD). It is specifically the analogue of LSD in which one of LSD's carbon atoms in the ergoline ring system, the carbon at position 4, has been removed.