Total synthesis of suaveoline and norsuaveoline via intramolecular oxazole–olefin Diels–Alder reaction

Total synthesis of two Rauwolfia alkaloids, suaveoline (1) and norsuaveoline (2), has been achieved through a highly stereoselective route starting from l-tryptophan methyl ester (9) and exploiting the intramolecular Diels–Alder reaction of the oxazole–olefin 16.