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 5N 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 2 1/2 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 1N 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 0-0.7N 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