Total Synthesis of (+)-Sieboldine A

摘要

The first total synthesis of (+)-sieboldine A was completed in 20 steps from readily available (3aS,6aR)-3,3a,4,6-atetrahydro-2H-cyclopenta[b]furan-2-one (>5). Key steps are: (a) a pinacol-terminated 1,6-enyne cyclization reaction to form the cis-hydrindanone core (>11 → 12), (b) formation of the spiro tetrahydrofuran ring by stereoselective DMDO oxidation of tricyclic dihydropyran intermediate >15, and (c) formation of the unprecedented N-hydroxyazacyclononane ring by cyclization of a thioglycoside precursor (>18 → 19).