The total synthesis of (±)hinesol and (±)epihinesol

Abstract

The tricyclic ketal ketones 15a and 15b have been obtained in an isomeric ratio of 9:1 (4 → 5 → 6 → 7 → 8 → 9 → 10 → 11 → 12 → 13 → 14 → 15a + 15b). Compound 15a was converted in seven (or eight) steps to (±)epihinesol (3) (15a → 29 → 32 → 48 → 49 → 47 (or 32 → 39 → 38 → 44 → 47) → 50 → 3) and compound 38 was transformed into (±)hinesol (2) in rive steps (38 → 76 → 77 → 62 → 63 → 2). The identity of epihinesol and agarospirol was confirmed by formation of a common epoxide.