Liposidomycins - Synthetic Studies Towards the Ribosyldiazepanone Moiety.

A synthesis of the enantiopure 2-ribosyl-1,4-diazepan-3-one core of liposidomycins, a class of complex lipid nucleoside antibiotics, according to a flexible asymmetric synthesis strategy is described. It involves two building blocks, an enantiopure α-azido-β,γ-epoxybutanol readily available from L-ascorbic acid, and an α-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.