Synthese de derives de la purpurosamine C,composant de la gentamicine C1a

Abstract The synthesis of derivatives of purpurosaimine C and epi -purpurosamine C is described, from methyl 2,3,4,6-tetra-O-methylsulphonyl-α- d -galacto and glucopyranosides 2 and 3 by reaction with azide ion to give diazides 4 and 5 , transformed in a series of reactions via epoxides 6 and 7 into the corresponding olefines 16 and 17 , thermal rearrangement to give diazides 18 and 19 , which were transformed into the methyl glycosides 27 and 29 and mercaptolysis with ethanethiol followed by N -acetylation, gave 2,6-diacetamido-2,3,4,6-tetradeoxy- d -erythro-hexose diethyl dithioacetal 30 (identical with authentic 30 prepared from gentamicin C 1a )and 2,6-diacetamido-2,3,4,6-tetradeoxy- d - threo -hexose diethyl dithioacetal 31 , an enantiomer of a mercaptolysis product of dihydrosisomicin.