Synthesis of 1,5-lactones of 3-deoxy- d- manno-2-octulopyranosonic acid (KDO)

Abstract

An unambiguous synthesis of methyl 3-deoxy-α- d- manno-2-octulopyranosidono-1,5-lactone from methyl (methyl 3-deoxy-α- d- manno-octulopyranosid)onate via the 7,8- O-isopropylidene derivative is described. Treatment of the 4,5-stannylene derivative of this acetal with benzyl bromide gave the 1,5-lactone from which the protecting groups were removed. The acetylated 1,5-lactone was produced by acetylation of ammonium 3-deoxy- d- manno-2-octulosonate or treatment of the pyridinium salt with dicyclohexylcarbodi-imide and acetylation. No lactone was produced when only HO-7 was unsubstituted. When treated with an excess of 2-methoxypropene, methyl (methyl 3-deoxy-α- d- manno-2-octulopyranosid)onate afforded the 4,5:7,8-di- O-isopropylidene derivative, from which the 7,8-acetal group could be removed selectively.