Synthesis of Polyhydroxylated Pyrano-Pyrrole Derivatives from Carbohydrate Precursors

The efficient synthesis of novel polyhydroxy‐tetrahydropyrano‐pyrroles from acetylenic carbohydrate precursors in three to four steps is described. The methodology involves, as key steps, the ring contraction of pyridazine intermediates obtained by an inverse‐demand Diels–Alder reaction and subsequent intramolecular lactonization