Using a sultone as the key intermediate, the first enantioselective total synthesis of the antileukemic 1,10-seco-eudesmanolides (–)-eriolanin (1) and (–)-eriolangin (2) was achieved, which also established the hitherto unknown absolute configuration of these sesquiterpene lactones. Starting from 2-bromo-1-(2-furyl)ethanone, 24 steps were required to generate the common basic structure and two additional steps in each case for completion of the natural products. The effect of 1 and 2 on the cell cycle of human leukemia (HL-60) cells was investigated by flow cytometry.