C(O)(C(F)(F)F)=[O:2].C(O[C@@H](CCNC(OCC1C=CC=CC=1)=O)C(=O)[O:19][C:20]1[C:25](F)=[C:24](F)[C:23](F)=[C:22](F)[C:21]=1F)(=O)C1C=CC=CC=1.[NH4+:45].[OH-:46]>O>[N+:45]([C:21]1[CH:22]=[CH:23][CH:24]=[CH:25][C:20]=1[OH:19])([O-:2])=[O:46]To a stirring solution of TFA (1 mL) and water (0.2 mL) at 0° C. was added 3′,4′,3′″,4′″-tetra-deoxy-1-(N-Boc-2(S)-hydroxy-3-amino-propionyl)-neomycin (3, 0.164 mmol) and the reaction was stirred for 30 minutes, and checked for completeness by MS. Upon completion, the reaction was diluted with water (10 mL) and lyophilized to yield a crude, which was dissolved in conc. NH4OH (1.5 mL) and purified on a 1-inch reverse-phase HPLC column (0-10% ACN, 10 mM NH4OH) to yield 3′,4′,3′″,4′″-tetra-deoxy-1-(2(S)-hydroxy-3-amino-propionyl)-neomycin (4, 48.7 mg, 0.076 mmol, 40% yield): MS: m/z (M+H)+ calc. 638.0, obs.: 638.2; CLND 99.6% purity.
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