Synthesis of saframycins. I. Total synthesis of (.+-.)-saframycin B and its congeners.

Abstract

We describe the total synthesis of the dimeric isoquinolinequinone antibiotic saframycin B (1) from tricyclic lactam 3. The key step is the stereoselective intramolecular cyclization of the aminoacetal 6. The structure of the pentacyclic intermediate 8 was confirmed by X-ray crystallography.