Total Synthesis of the Myrioneuron Alkaloid (-)-Schoberine B and Its Enantiomer (+)-Schoberine B

A dynamic kinetic asymmetric transformation, involving the generation of four stereogenic centers with a well-defined configuration, occurs in the cyclocondensation of diastereomeric mixtures of 2-oxocyclohexanepropionic acid racemates 6 with (1S,2R)-cis-aminoindanol: two major tetracyclic lactams, 7 a and 7 b, that differ in the configuration of the four stereocenters on the decahydroquinoline moiety were obtained. From the above lactams, the removal of the chiral auxiliary, the introduction of a 2-piperidone ring, and the closure of the diazine ring complete the first enantioselective total synthesis of the Myrioneuron alkaloid (-)-schoberine B and its enantiomer (+)-schoberine B.