MYXOCHELIN-B, MYXOCHELIN-C, MYXOCHELIN-D, MYXOCHELIN-E AND MYXOCHELIN-F - A NEW STRUCTURAL PRINCIPLE FOR POWERFUL SIDEROPHORES IMITATING NATURE

The synthesis of the natural siderophore myxochelin B (1(s)) and its e nantiomer 1(R) is described. 1(S) and 1(R) served as precursors for th e synthesis of new hexadentate siderophores, the myxochelins C (7(s)) and C-R (7(R)), D (14(S)) and D-R (14(R)), E (19(S)) and (RS)-F (26(R, S)), with 2,3-dihydroxybenzoate (DHB) ligands and the simple backbones of asymmetric 1,2,n-triamino-n-alkanes. For the myxochelins C, D, E a nd F n is 6 (from lysine), 5 (from ornithin), 4 (from asparagine amide ) and 7 [from (+/-)-2-aminopimelic acid], respectively. The additional amino functions in the starting compounds were provided by dehydratio n of the corresponding primary amides, and subsequent reduction of the nitriles by cobalt boride in methanol. All new siderophores supply ba cteria with ferric ions with an efficiency which depends on their chai n length and stereochemistry. They show significant activity against t he cytomegalo virus.