A new methods for the 3'-deoxygenation of butirosins A and B.

An aziridine ring-formation involving the reaction of adjacent amino and alcohol groups with triphenylphosphine, carbon tetrachloride, and triethylamine was applied at the 2' and 3' positions of butirosin A (1a) and B (1b). The amino groups at the 2' position of 1a and 1b were p-methoxybenzylated to increase the nucleophilicity of the nitrogen atom and to avoid the formation of a P-N linkage, and the N-p-methoxybenzyl derivatives were converted into the aziridine derivatives, which were then subjected to hydrogenolysis and removal of the protecting groups to give 3'-deoxybutirosin A (7a) and B (7b), respectively. This new method is compared with the conventional N,O-protecting method that involves several complex steps.