Multigram Scale Synthesis of A21, A New Antibiotic Equally Effective and Less Toxic than Amphotericin B

A21 (2) is a new polyene macrolide Amphotericin B amide antibiotic derived from amphotericin B AmB (1), which has been tested extensively on preclinical trials showing the same antimycotic effectiveness and increased margin of safety over AmB (1). We present the multigram scale synthesis, isolation, purity assessment by HPLC, and key aspects of its characterization by NMR studies of A21 (2).