Solid-Phase Synthesis of a Branched Hexasaccharide Related to Lacto-N-Hexaose

Lactose donor 2 has been designed for the solid-phase synthesis of branched milk oligosaccharides and its synthesis from lactose is presented. This compound has been employed, together with the known DMM-protected lactose donor 3, in the solid-phase synthesis of the branched hexasaccharide 1 related to lacto-N-hexaose. An isolated yield of 13% over six steps (71% per step) was obtained from linker-loaded resin 4. This synthesis constitutes a successful application of the ring-closing metathesis-based linker strategy for the solid-phase synthesis of oligosaccharides.