Synthesis and antifungal selectivity of new derivatives of amphotericin B modified at the C-13 position.

The syntheses of the first amphotericin B derivatives to be modified solely at the C-13 hemiketal position are described. Selective functionalisation at this position is facilitated by use of the allyl ester as a C-16 carboxylate protecting group on the amphotericin B nucleus. In in vitro tests all compounds showed markedly reduced haemolytic activity against mammalian erythrocytes while two of the novel 13-alkoxy derivatives retained good antifungal activity.