1-exo-Alkylidene-2,3-anhydrofuranoses: Valuable Synthons in the Preparation of Furanose-Based Templates

Highly functionalized 1-exo-alkylidene-2,3-anhydro-, and 1'-halo-1-exo-alkylidene-2,3-anhydrofuranoses can be prepared in four or five steps, respectively, from D-mannose. These compounds feature a variety of functionalities, including a double bond, an oxirane, an allylic oxirane and (in the case of the 1'-halo derivative) an alkenyl halide. The reactivity of each functionality in these derivatives has been explored, and the usefulness of these substrates has been demonstrated with the preparation of furanose-based carbohydrate templates with up to four sites of molecular diversity.