1D-LSD (1-(1,2-dimethylcyclobutane-1-carbonyl)-lysergic acid diethylamide hemi-L-tartrate) is a psychedelic research chemical and lysergamide derivative with an ergoline backbone. 1D-LSD is a prodrug of LSD and an analogue of 1V-LSD. Since it is a prodrug, it shares many similar properties with LSD itself but also 1V-LSD, 1P-LSD, 1cP-LSD and 1B-LSD. However, 1D-LSD also has some distinguishing features including a faster onset and slightly shorter duration compared to its cousins.
1D-LSD contains a cyclobutanecarbonyl group bound to the indole nitrogen of the LSD backbone, this cyclobutane group is further substituted with two methyl groups to form a highly-strained pro-moiety. Due to the strained configuration of the 1,2-dimethylcyclobutane unit, 1D-LSD rapidly metabolises on ingestion providing a quick onset of action.