JWH-098 is a synthetic cannabinoid receptoragonist from the naphthoylindole family. It is the indole 2-methyl derivative of a closely related compound JWH-081, but has markedly different affinity for the CB1 and CB2 receptors. While JWH-081 is around 10x selective for CB1 over CB2, in JWH-098 this is reversed, and it is around 4 times weaker than JWH-081 at CB1 while being six times more potent at CB2, giving it a slight selectivity for CB2 overall. This makes JWH-098 a good example of how methylation of the indole 2-position in the naphthoylindole series tends to increase CB2 affinity, but often at the expense of CB1 binding. JWH-098 is illegal in Russia, Sweden, and the UK, although it is unclear whether it has any history of human use.
^Huffman JW, et al. Structure–activity relationships for 1-alkyl-3-(1-naphthoyl)indoles at the cannabinoid CB1 and CB2 receptors: steric and electronic effects of naphthoyl substituents. New highly selective CB2 receptor agonists. Bioorganic and Medicinal Chemistry. 2005; 13:89-112. PMID 15582455