(1R)-1-[(1S)-2-({(1S)-1-[(benzyloxy)carbonyl]-2-methylpropyl}amino)-1-methyl-2-oxoethyl]octyl 4-[(tert-butoxycarbonyl)(methyl)amino]-2,4,5-trideoxy-3-O-(methoxymethyl)-5-phenyl-L-erythro-pentonate