Asymmetric syntheses of (-)-erinapyrones A and B

(-)-Erinapyrone A and (-)-erinapyrone B have been synthesized in short steps from bis-2-(1,3-dithianyl)methane, (S)-propylene oxide and (R)-benzyl glycidyl ether. These synthetic compounds, however, showed higher specific rotation values than those of the natural products. Both enantiomers of erinapyrones A and B were synthesized by the use of antipodal epoxides. These enantiomers showed same specific rotation values with reverse signs. The racemic compounds were also synthesized as standard samples for analysis on chiral gc column for optical resolution.