Mode-switchable aldol cyclization of a diketone precursor enables a novel collective synthesis of divergent gabosine-type carbasugars.

Two new synthetic approaches to anhydrogabosines are developed from the polyoxygenated aldol cyclization intermediates, bearing different O‐protecting groups, which were transformed to various gabosine‐type cyclitols. Selective sulfonylation on the required hydroxyl group of the intermediates and the subsequent oxirane ring closure are employed as the key steps in both approaches, by which (+)‐epoxydon, (–)‐phyllostine, (–)‐RKTS 33, and (–)‐parasitenone were synthesized from δ‐d‐gluconolactone.

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