4-MeO-PV9 CAS # 89669-27-9 is an alpha-pyrrolidinopentiophenone research chemical and analog in which the pentyl chain is simply extended by three carbons. 4-methoxy PV9 differs from alpha-pyrrolidinopentiophenone by using the fourth or para-methoxy group at the site belonging to the phenyl group. The physiological as well as toxicological characteristics of the material are not well-known.