Total synthesis of (+)-FR-900493 and establishment of its absolute stereochemistry

The first total synthesis of (+)-FR-900493, an antibacterial nucleoside antibiotic possessing a 6′-N-alkyl-5′-O-aminoribosyl-glycyluridine structure, is described, and its relative and absolute stereochemistries were established. Key elements of the approach include the early-stage introduction of the aminoribose moiety and two sequential reductive alkylations of an amino group at the 6′-position. This synthetic strategy could be applicable to the synthesis of related nucleoside antibiotics, such as the more potent antibacterial nucleoside antibiotics, muraymycins.