RU-28306, also known as 4,ñ-methylene-N,N-dimethyltryptamine (4,ñ-methylene-DMT), is a synthetic indole alkaloid derivative which acts as a serotonin receptor agonist, with selectivity for 5-HT<sub>1</sub> and 5-HT<sub>2</sub> subtypes. It can be regarded as a conformationally restricted tricyclic derivative of DMT or a structurally simplified derivative of LSD. The binding affinity of racemic RU-28306 is closer to that of DMT than LSD, though with relatively higher affinity for 5-HT<sub>2</sub> subtypes and lower for 5-HT<sub>1</sub>. It has been sold as a designer drug and was first reported to the EMCDDA by a forensic laboratory in Slovenia in 2017. It was subsequently patented by Delix Therapeutics in 2021.