Furthermore, the indole core is substituted at R3 that has a carbonyl group which can be also bonded to some napthalene moeity. Napthalene can be a bicyclic structure of two fused benzene rings. This carbonyl bridge of JWH-018 classifies it as a ketone. JWH-018 is surely an analog of THJ-018, https://jwh01856320.blogsidea.com/39322231/497-fundamentals-explained