The absolute configuration determination of naturally occurring diacetylenic spiroacetal enol ethers from Artemisia lactiflora

Six new naturally occurring diacetylenic spiroacetal enol ethers, Lactiflodiynes A–F (1–6), together with five known congeners (7–11), were isolated from the whole plant of Artemisia lactiflora (Compositae). The structures were elucidated by extensive spectroscopic methods, X-ray crystallography, chemical transformations, and CD. The absolute configuration of Lactiflodiyne A (1) was determined to be 2R, 5S, 6S, and 7R by an X-ray crystallographic diffraction experiment using Mo Kα radiation with the absolute parameter of 0.01(8). In combination with CD, the absolute configurations of compounds 2–11 were confirmed by chemical transformations using 1 as the starting material.