Divergent Approach to Gabosines and Anhydrogabosines: Enantioselective Syntheses of (+)-Epiepoformin, (+)-Epoformin, (+)-Gabosine A, and Gabosines B and F

A divergent approach to polyoxygenated methylcyclohexanes has been applied to synthesize several gabosines and anhydrogabosines. The starting hydroxycyclohexenone, which is readily available in any antipodal form, provides access to both enantiomers of the target compounds. The syntheses of anhydrogabosines involve three main transformations: alpha-methylation, epoxidation, and sulfur removal, whereas the syntheses of gabosines require an additional epoxide hydrolysis step. The strategy has been applied to the synthesis of (+)-epiepoformin, (+)-epoformin, (+)-gabosine A, and gabosines B and F, through straightforward sequences in good overall yields.