Liposidomycins - Synthetic studies towards the ribosyldiazepanone moiety

A synthesis of the enantiopure 2-ribosyl-1,4-diazepan-3-one core of liposid omycins, a class of complex lipid nucleoside antibiotics, according to a fl exible asymmetric synthesis strategy is described. It involves two building blocks, an enantiopure alpha -azido-beta,gamma -epoxybutanol readily avail able from L-ascorbic acid, and an alpha -ribosylamino acid obtained from D- ribose. Subsequent cyclization by regiospecific nucleophilic opening of the epoxide by the amino acid followed by peptidic coupling affords the target ribosyl diazepanone.