Total synthesis of the supposed structure of (-)-sclerophytin A and an improved route to (-)-7-deacetoxyalcyonin acetate

[GRAPHICS] Stereoselective acid catalyzed rearrangement of 15 --> 16 is the central st ep in total syntheses of (-)-7-deacetoxyalcyonin acetate (1) and the compou nd with the alleged structure of sclerophytin A (2). Since tetracyclic diet her 2 is not identical to sclerophytin A, the structure of this antineoplas tic marine diterpene must be revised. The conversion of 15 --> 16 demonstra tes for the first time that tetrahydrofurans containing (Z)-1-methylalkenyl side chains can be prepared by Prins-pinacol rearrangements.