Benzaldehyde → (2S,3R,4R,5S,6S)-2-(aminomethyl)-6-[(1R,2R,3S,4R,6S)-4,6-diamino-3-[(2S,3R,4S,5S,6R)-4-amino-3,5-dihydroxy-6-(hydroxymethyl)oxan-2-yl]oxy-2-hydroxycyclohexyl]oxyoxane-3,4,5-triol

Participants

Reaction Conditions

Reaction Steps

Kanamycin A sulphate (24.3 g., 0.03 mole) was dissolved in water (150 ml.) and the pH adjusted to 6 by the dropwise addition of 5 N hydrochloric acid. Sodium cyanoborohydride (1.95 g., 0.03 mole) was added and the mixture was cooled to 0° C. and stirred while a solution of benzaldehyde (3.61 g., 0.033 mole) dissolved in methanol (15 ml.) was added slowly over the course of 21/2 hours. The mixture was allowed to warm to room temperature. After 16 hours the pH of the solution was adjusted to 5.5 by the addition of 1 N hydrochloric acid and the solution was filtered and added to a column of Amberlite CG-50 ion-exchange resin in the ammonium-ion form. Elution first with water and then with a gradient of ammonium hydroxide of increasing concentration from 0-0.7 N gave as major product 3-N-benzylkanamycin A contaminated with some 1-N-benzyl derivative (5.0 g., 28%) Rf 0.44 in methanol-chloroform-17% ammonium hydroxide 4:1:2. (Kanamycin A gave an Rf value of 0.15).

Provenance & Evidence