Synthesis of the Aromatic and Monosaccharide Moieties of Staurosporine

Efficient synthetic routes have been developed for the heteroaromatic unit 4 and some aminohexoses similar to 5, which are structural fragments of staurosporine (1). Aromatic lactone 4 has been prepared in four steps from 3,4-dibromomaleimide in good overall yield. A strategy utilizing Diels-Alder [4 + 2] cycloadditions of benzyl sulfinylcarbamate was used to synthesize staurosporine amino sugars in both the pyranose form 37 and in acyclic versions 38, 41, and 42. A novel feature of the work involved stereospecific syn epoxidations of the 3,6-di-hydrothiazine oxide adducts 15 and 16 directed by the sulfinyl oxygen.