Synthetic studies directed toward naturally occurring tetramic acids. 3. Synthesis of (-)-methyl ydiginate and the tetramic acid subunit for streptolydigin

Article abstract of DOI:10.1021/jo00379a036

A concise stereocontrolled and enantioselective synthesis of the N-glycosylated tetramic acid subunit 2 required for streptolydigin (1) is described. Key features of the convergent synthesis include the condensation of aminosuccinimide 3 with pyrrolidinorhodinose 16 to β-glycosylamine 17 and eventual elaboration of tetramic acid 2 by a Dieckmann condensation. The structure and absolute stereochemistry of 17 was confirmed by correlation with (-)-methyl ydiginate (4) and its 4′-O-acetyl derivative 19, previously obtained from a major degradation product of natural streptolydigin (1).