Access to the Bicyclic Core of Isatisine, and an Investigation of Its Antibacterial Activity

A chemoselective Dieckmann ring closure using an oxazolidine derived from serine may be used to generate a tetramic acid, the further manipulation of which by reduction and ring closure leads to the bicyclic core of isatisine; depending on the nature of the ring closing electrophile, different diastereomers are obtained. None of the compounds from this sequence exhibited activity against S. aureus but several showed activity against E. coli.