Enantioselective Synthesis of the AB-Ring System of the Antitumor Antibiotic Tetrazomine

Abstract
The synthesis of the 1,2,3,4-tetrahydroisoquinoline moiety of tetrazomine was accomplished in 18 steps and in 3% overall yield from commercially available o-anisaldehyde. The reaction sequence utilizes a Sharpless asymmetric dihydroxylation to install the stereocenter and an intramolecular Friedel−Crafts hydroxyalkylation with an N-protected 2-oxo-acetamide to close the heterocyclic ring.