Our synthesis of ammonium 3-deoxy-D-manno-2-octulosonate (ammonium KDO, 16) from D-mannose (3) proceeds in 10 one-flask operations in 1.5-1.6% overall yield (66% per operation). The strategic reaction is a C-C bond construction at C6of D-mannose via photochemically induced radical cross coupling of a-ethoxyacrylonitrile with an alkyl cobaloxime derivative of D-mannose, in aqueous ethanol without protection of carbohydrate hydroxyls. In this paper we provide full experimental details of our KDO synthesis. In addition we provide some observations and insights on vanadium-catalyzed oxidations of a-hydroxy acids to a-keto acids.
ASJC Scopus subject areas
- Organic Chemistry