Abstract Diels-Alder cycloaddition of nitrosobenzene to 1-methoxycarbonyl-1, 2- dihydropyridine led in high yield to the endocyclic hydroxylamine adduct 5, which was successively oxydized with potassium permanganate and hydrogenolyzed to give the new aminosugar 4, 5-dideoxy-5-methoxycarbonylamino-4-phenylamino-α-D, β-L lyxopyranose 7.