Chiral phosphoric acid-catalyzed desymmetrizative glycosylation of 2-deoxystreptamine and its application to aminoglycoside synthesis

This work describes chiral phosphoric acid (CPA)-catalyzed desymmetrizative glycosylation of meso-diol derived from 2-deoxystreptamine. The chirality of CPA dictates the outcome of the glycosylation reactions, and the use of enantiomeric CPAs results in either C4-glycosylated (67:33 d.r.)or C6-glycosylated (86:14 d.r.) 2-deoxystreptamines. These glycosylated products can be converted to aminoglycosides, and the application of this strategy to the synthesis of protected iso-neamine and iso-kanamycin B with inverted connection at the C4 and C6 positions is described.