The synthesis of the title compound from the Diels-Alder adduct of diethyl ketomalonate and 1, 3-butadiene (nine steps, 13% overall yield) is described. The key step is a transannular “bromolactamization” reaction, which sets up the stereocontrolled functionalization of the pyran ring. The use of resolved p-methoxyphenethylamine as the source of the amino group allows the synthesis of both the D (natural) and L (unnatural) series amino sugars.
