Efficient assembly of mono- and bis(1,2,4-oxadiazol-3-yl)furoxan scaffolds via tandem reactions of furoxanylamidoximes

Abstract

A general, facile, highly effective one-pot protocol for the synthesis of new types of heterocyclic systems incorporating mono- and bis(1,2,4-oxadiazol-3-yl)furoxan cores based on the tandem heterocyclization of furoxanylamidoximes with various aliphatic, aromatic, and heterocyclic carboxylic acid chlorides under very mild conditions (Cs₂CO₃, MeCN, 20 °C) has been developed. In addition, a solvent-free approach for the (1,2,4-oxadiazol-3-yl)furoxan synthesis by the reaction of furoxanylamidoximes with trimethyl orthoformate catalyzed by Sc(OTf)₃ has been achieved. The advantages of step economy and scope make these reactions a powerful tool for assembling heterocyclic scaffolds of general chemistry and biomedical interest.