The structure of 2-(pyrrolidin-1-yl)-1,4-naphthoquinone, C(14)H(12.95)Cl(0.05)NO(2), (I), is actually a 0.95:0.05 mixture including 2-chloro-3-(pyrrolidin-1-yl)-1,4-naphthoquinone as a minor impurity, but (I) was resolved as a single molecule containing a Cl atom with 5% occupancy at the 3-position. Compound (I) was prepared from the fully chloro-substituted analogue in an attempt to produce the disubstituted pyrrolidinyl derivative. 2-Phenylsulfanyl-3-(pyrrolidin-1-yl)-1,4-naphthoquinone, C(20)H(17)NO(2)S, (II), was also prepared from 2-chloro-3-(pyrrolidin-1-yl)-1,4-naphthoquinone, using a strong exocyclic nucleophile. The structure of (II) differs from previous structures of 2,3-dichloro-1,4-naphthoquinone and its derivatives in that the naphthoquinone ring is non-planar.