Polyoxamic acid , 2-amino-2-deoxy-L-xylonic acid, is synthetized by thiophenoxide opening of a five-carbon chiral hydroxylated aziridine easily derived from L-arabinose. The formation of the carboxy group resulted lrom a Pummerer reaction. Polyoxins belong to a group of antifungal antibiotics produced by certain species of Streotomyces, which inhibit the chitin synthetase of a variety of phytopathogenic fungi(l). Recent studies suggest that these compounds (or their analogues) may also be therapeutically useful against Candida a fungal pathogen which affects humans(2). Polyoxins all incorporate a non-proteinic amino acid, polyoxamic acid 1. The unusual polyhydroxy a-amino acid 1 is coupled in polyoxins by a peptide linkage to one of several related nucleoside moieties. COOH Hz Y-0 H Ii % H,O H POLYOXINS POLYOXAMIC ACID Different chemical syntheses of polyoxamic acid have been proposed, most of them relying on carbohydrates as chiral building blacks(3)
; recently a stereoselective synthesis starting from D-serine was also reported(4). We now report a rapid, enantiospecilic synthesis of polyoxamic acid 1, and more usefully of the derivative 8 suitably protected for peptide coupling, from the easily available pentose : L-arabinose.