γ1-N-ACYLATION OF GENTAMICIN C1a, BY A CYCLIC, CHIRAL γ-AMINO-α-HYDROXY ACID RELATED TO THE (S)-4-AMINO-2-HYDROXYBUTYRIC ACID

A semisynthetic aminoglycoside antibiotic 15, containing a cyclic γ-amino-α-hydroxy acid, related to the 1-N-4-amino-2-hydroxybutyric acid (AHBA) side chain of butirosins and amikacin, has been prepared. Conveniently protected 3, 2', 6'-tris-N-tert-butoxycarbonylgentamicin Ca, (12) was condensed with the phtalimido active ester 10 to give after catalytic reduction and deprotection, the hitherto unknown 1-N-substituted gentamicin C1a 15. The requisite side chain was synthesized from the readily available D-(-)-quinic acid. The antibacterial properties of 15 are given.