A Substituent‐Directed Strategy for the Selective Synthesis of L‐Hexoses: An Expeditious Route to L‐Idose

L‐Hexoses are rare but biologically significant components of various important biomolecules, however, most are prohibitively expensive if commercially available, limiting their study and biotechnological exploitation. New, efficient methods to access L‐hexoses and their derivatives are thus of great interest. In a previous study, we showcased a stereoselective Bu 3 SnH‐mediated transformation of a 5‐ C ‐bromo‐D‐glucuronide to an L‐iduronide. We have now drawn inspiration from this result to derive a new methodology which can be harnessed to access other L‐hexoses. DFT calculations demonstrate that a combination of a β‐F at the anomeric position and a methoxycarbonyl substituent at C‐5 is key to optimising the selectivity for the L‐hexose product. Our investigations have also culminated in the development of the shortest known synthetic route to a derivative of L‐idose from commercially available starting material (45% yield over 3 steps). Collectively, these results address the profound lack of understanding about how to synthesise L‐hexoses in a stereoselective fashion.