A TOTAL SYNTHESIS OF NANNOCHELIN-A - A SHORT ROUTE TO OPTICALLY-ACTIVE N-OMEGA-HYDROXY-ALPHA-AMINO ACID-DERIVATIVES

The total synthesis of nannochelin A, a lysine-basd cinnamoyl hydroxam ate produced by Nannocystis exedens, is described. The key transformat ion involves construction of the N-epsilon-cinnamoyl-N-epsilon-hydroxy -L-lysine methyl ester fragment by partial reduction of the lactam car bonyl of 6 derived from L-lysine, oximation of this aldehyde equivalen t compound 8 with O-[2-(trimethylsilyl)ethyl]hydroxylamine, and reduct ion of the oxime 10, followed by N-acylation prior to coupling with th e external carbonyls of citric acid. This methodology will be applicab le to synthesis of other hydroxamate-containing siderophores bearing h ydrogenolyzable groups in the molecule.