Recent Advances in the Applications of D- and L-Form 1,6- Anhydrohexopyranoses for the Synthesis of Oligosaccharides and Nature Products

The D- and L-form 1,6-anhydrohexopyranoses are valuable building blocks in the synthesis of carbohydrate molecules as well as nature products. Their bicyclo[3.2.1]octane framework possesses rigid conformation that has several advantages and offers unique reactivity patterns in comparison with their corresponding hexopyranoses. A variety of practical and convenient routes developed for their preparation over past two decades have been reviewed and analyzed here. The novel reactions for regioselective discriminations of three hydroxy groups at C2, C3, and C4 via chemical or enzymatic processes, newer methodologies for opening the 1,6-anhydro ring, and their applications to synthesize the biologically significant and structurally diverse oligosaccharides and nature compounds are described.