Antileukemic tropoloisoquinoline alkaloids, pareirubine A (1) and gandirubrine (2), at first have been isolated from.Abuta concolor (Menisper-maceae). Methylation of 1 and 2, existing in solution as a mixture of tautomersgave the corresponding four methyl derivatives (3 -6). Thioimerubrine (7) andthioisoimerubrine (8) were prepared by the nucleophilic substitutions of themethoxyl groups at C-11 and -10, respectively. Acetylation of 1 and 2produced the corresponding mono-acetyl tautomers (9 and 10). Antileukemicactivity of these derived tropoloisoquinoline alkaloids is also reported.