Synthesis of the octahydroindole unit of aeruginosins via asymmetric hydrogenation of the Diels–Alder adducts of 2-amido-2,4-pentadienoate

An optically active octahydroindole, the core unit of aeruginosins (Choi) was synthesized. The Diels–Alder reaction of Danishefskyʹs diene with methyl (Z)-2-acetamido-2,4-pentadienoates provided the adducts regioselectively in good yield. The adducts were converted to the l-Choi precursor by asymmetric hydrogenation, followed by acid cyclization.