Ring‐Junction‐Substituted Polyhydroxylated Pyrrolizidines and Indolizidines from Ketonitrone Cycloadditions

Abstract

A 1,3‐dipolar cycloaddition reaction of carbohydrate‐derived five‐membered cyclic ketonitrones with alkynes and alkenes was developed as an efficient and regioselective process to access highly functionalised isoxazolines and isoxazolidines bearing a quaternary centre α to the nitrogen atom. The latter compounds were used as intermediates for the synthesis of unprecedented ring‐junction‐substituted polyhydroxylated pyrrolizidines and indolizidines. These compounds were evaluated against a panel of glycosidases, and showed moderate but selective inhibition of α‐glucosidases.

Recent Developments in the Synthesis of Polyhydroxylated Indolizidines

“…Synthesis employing 1,3‐DCA of nitrones in the preparation of ring‐junction substituted polyhydroxy indolizidines was also reported by Lieou Kui and coworkers [119] two years later (Scheme 24). Ketonitrone 146 was prepared in two steps [120–121] from L‐xylose derived aldonitrone 145 .…”