Determination of the Absolute Configuration of (−)-Linderol A

Abstract

(−)-Linderol A [(−)-1; 5aR^*,6R^*,9R^*,9aS^*-4-cinnamoyl-3,6-dihydroxy-1-methoxy-6-methyl-9-(1-methylethyl)- 5a,6,7,8,9,9a-hexahydrodibenzofuran], a constituent of Lindera umbellata (Lauraceae), shows the potent inhibitory activity on the melanin biosynthesis of cultured B-16 melanoma cells. Its structure was determined by Sashida et al. except for its absolute configuration. We already reported the first total synthesis of (±)-1. An acetate [(±)-2] of the intermediate [(±)-3] in the total synthesis of (±)-1 separated to (+)- and (−)-2 by using HPLC with a chiral column. (−)-Camphanyl ester [(−)-4] of the triol [(−)-3] was subjected to X-ray crystallographic analysis, and the absolute configuration could be determined. The triol [(−)-3] was derived to (−)-1 according to the previous total synthesis of (±)-1. From these facts, the absolute configuration of (−)-1 should be 5aR,6R,9R,9aS