The reaction of (+)-euryfuran 1 with several benzo-, naphtho- and benzo[b]thiophene-1,4-quinones in acetic acid yields the corresponding euryfuryl-1,4-quinones 3, 5, 7, 8, 10, 12, and 14. The structure of compounds 7, 8, 12, and 14 was assigned through 2D NMR 1H-13C HMBC experiments. The influence of the acidity of the solvent upon the reactivity and regioselectivity of the quinones to the oxidative coupling reaction, is discussed. The in vitro activity of the euryfurylquinones and their corresponding precursors against Leishmania amazonensis is described. © 2003 Elsevier Ltd. All rights reserved.