SYNTHESIS AND REACTIVITY OF CARBOHYDRATES CONTAINING 3‐MEMBERED HETEROCYCLES, KEY PRECURSORS OF MODIFIED SUGARS AND MIMETICS

Abstract

Molecules containing three‐membered heterocycles, including oxiranes (epoxides), thiiranes (episulfides) and aziridines, are considered privileged structures as they serve as key precursors or intermediates for the synthesis of a varied range of organic compounds, such as natural products, mimetics and pharmaceuticals. The principal advantage of this type of heterocycles is their reactivity towards the nucleophilic ring‐opening, which usually occurs in a regioselective manner, resulting in the formation of 1,2‐disubstituted products. When attached to a chiral scaffold, such as a carbohydrate molecule, the ring‐opening process is usually highly diastereoselective. Therefore, these compounds have been extensively employed in the field of carbohydrates for the synthesis of enantiomerically pure modified sugars that are useful as glycobiology tools. This review presents an overview of the recent methodologies developed for the construction of epoxide, thiirane, and aziridine rings from common or modified sugars. Due to their structural similarity to carbohydrates, three‐membered heterocyclic derivatives of cyclitols and carbasugars have been included. All these compounds, and their ring‐opening derivatives have shown to be crucial in the synthesis of glycomimetics, which display diverse biological activities. These include enzyme inhibition, binding to lectin receptors, and more recently, the use as probes for the diagnosis and monitoring of diseases.