Enantioselective Construction of Octahydroquinolines via Trienamine-Mediated Diels-Alder Reactions.

A trienamine-mediated asymmetric Diels-Alder reaction using a 5-nitro-2,3-dihydro-4-pyridone derivative as a dienophile in the presence of a secondary amine organocatalyst derived from cis-hydroxyproline was discovered. The reaction provides optically active octahydroquinolines through an endo-selective [4 + 2] cyclization pathway. The following stereoselective denitration, isomerization, and/or hydrogenation generated divergent stereoisomers of decahydroquinolines, which are useful synthons for the total synthesis of Lycopodium alkaloids.