Process for the synthesis of exochelins

A process for the synthesis of an Exochelin comprising the steps of generating L-N-[(2-benzyloxy-(benzoyl)] serine or L-N-[2-benzyloxy (benzoyl)] threonine, creating L-N-t-Boc- epsilon -hydroxynorleucine and reacting same to produce L-N-Boc- epsilon -bromonorleucine trimethylsilylethyl ester, providing a dicarboxylic acid and forming an O-benzyl methyl hydroxamate from the dicarboxylic acid, coupling the O-benzyl methyl hydroxamate with the L-N-Boc- epsilon -bromonorleucine trimethylsilylethyl ester to give an L-N2-Boc-N6-methyl,N6-(benzyloxy) lysine 2-trimethylsilylethyl ester which incorporates the dicarboxylic acid as modified above, removing the N-tert-butoxycarbonyl protecting group from the L-N2-Boc-N6-methyl, N6-(benzyloxy) lysine 2-trimethylsilylethyl ester to yield a substituted lysine, and coupling the same with the L-N-[2-benzyloxy (benzoyl) serine or -threonine to yield a 2-trimethyl silylethyl ester of dibenzyl Exochelic acid, transforming the 2-trimethyl silylethyl ester of dibenzyl Exochelic acid to dibenzyl Exochelic acid, preparing benzyl epi-cobactin, forming an ester bond between the dibenzyl Exochelic acid and benzyl epi-cobactin to form an intermediate, and, hydrogenolytically removing three benzyl groups from said intermediate, resulting in the synthesized Exochelin. More particularly, a synthesis for Exochelin 786SM (R) is disclosed wherein the dicarboxylic acid is suberic acid and the serine form is utilized.