A novel method to prepare guanidine substituted aminoglycoside derivatives was developed.Free guanidine reacted with Cbz-protected aminoglycosides to produce guanidinylcarbonyl substituted derivatives.A methoxycarbonyl-protected intermediate was isolated,and the mechanism of guanidinylcarbonyl modification was proposed.With this method,six per- or part-guanidylcarbonyl substituted aminoglycosides were successfully obtained in good yields.Their in vitro antibacterial activities were essayed.
A series of urea-linked hydroxyl-alkylamine derivatives of aminoglycosides have been obtained by modification of neamine （1）, kanamycin （2） and ribostamycin （3） at 1, 6＇ and 3 N-sites, respectively, through selective cyclization and nucleophilic ring-opening of cyclic carbamates. All the products showed no noticeable activity in the antibiotic test in vitro. The result suggests that the urea-linked hydroxyl-alkylamine derivatives of aminoglycosides may not be suitable structures for the enhancement of antibiotic activity.
The 3＇-OH, 4＇-OH and 2＂-OH of kanamycin A were modified in search of new aminoglycosides to overcome resistant enzymes, ANTs and APHs. The key intermediate was a dibenzylidene-protected derivative of kanamycin A. The aimed sites were masked by benzyl, methyl and allyl groups. Multi-step reactions gave the desired aminoglycoside derivatives but showed less antibiotic activity than kanamycin A.
Aim To develop a novel selective protection strategy for the synthesis of ribostamycin cyclic carbamate derivatives. Methods Ribostamycin protected by carbobenzoxy group was treated with Nail, to give different protected intermediates under respective controllable cyclization reaction conditions. New ribostamycin derivative was obtained after the cleavage of carbobenzoxy groups. Result The novel selective protection of ribostamycin was achieved by the synthesis of protected intermediates. New ribostamycin derivative was obtained, but showed no expected antibacterial activity. Conclusion Several ribostamycin cyclic carbamate derivatives were obtained by novel selective protection strategy, which shows the practicability and convenience of the protection strategy. But these new ribostamycin derivatives containing cyclic carbamates structure may not be an ideal leading compound for antibiotic activity.
