Improved and large-scale synthesis of different protected D-glucuronals.

Although different protected D-glucuronals are used as precursors for the preparation of many compounds, standard procedures and large-scale syntheses are still not described in the literature. In the course of the development of different protected d-glucuronyl donors we developed several versatile methods that can be used for fast and reproducible preparation of large amounts of the key intermediates. D-Glucuronolactone was converted to methyl 3,4-di-O-acetyl-D-glucuronal applying a novel one-pot protocol, which allowed for large-scale synthesis. Introduction of silyl and benzyl groups was achieved using optimized procedures. Furthermore 3,4,6-tri-O-acetyl-D-glucal was used as starting material for an improved preparation of benzyl protected D-glucuronal, which significantly accelerates and simplifies similar methods described in the literature.