摘要：

We have achieved the synthesis of both enantiomers of the new piperidone type of chiral building block (1) by using bakers' yeast reduction of corresponding β-keto ester or lipase-mediated kinetic resolution of (±)-1 in optically pure state. Its application to the natural products synthesis also has been demonstrated. Thus, the new and flexible route to the diastereodivergent synthesis of the α,α'-disubstituted 3-piperidinol alkaloids was established, and the chiral synthesis of (+)-prosafrinine, (-)-iso-6-cassine, (-)-prosophylline, and (-)-prosopinine has been achieved. As another application to the synthesis of the natural products, we accomplished the first enantioselective total synthesis of the marine alkaloids clavepictine A, B, pictamine, and lepadin B, using an intramolecular Michael type of ring closure reaction to give the 4,6-cis-substituted quinolizidine ring system (3) or an intramolecular aldol type of cyclization to give the 4a,8a-cis-octahydroquinolinone ring core (4) as the key step, respectively, and the absolute stereochemistry of these marine alkaloids was determined by the present chiral syntheses.

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