Enantioselective Total Synthesis of (+)-Sieboldine A

The first total synthesis of (+)-sieboldine A was completed starting from 5-(p-methoxybenzyloxy)pentyne in 19 steps. The enantioselective Keck allylation provided the dienyne derivative, which was exposed to the Pauson–Khand conditions to afford the bicyclo[4.3.0]nonenone derivative with high stereoselectivity with an ee value of 93%. The following Ueno–Stork reaction formed the cis-hydrindane core with a quaternary carbon center. The late-stage Schmidt glycosylation led to the formation of the N-hydroxyazacyclononane ring.