Gold-catalyzed intermolecular tandem cyclization/[4 + 3] cycloaddition of 2-(1-alkynyl)-cyclopropyl pyridines with nitrones: an efficient strategy for the synthesis of [1,2]oxazepino[5,4-a] indolizines

Abstract

A new and efficient approach is described for the diastereoselective synthesis of [1,2]oxazepino[5,4-a] indolizines via a gold-catalyzed [4 + 3] cycloaddition reaction of 2-(1-alkynyl)-cyclopropyl pyridine with nitrones. This methodology has great potential to construct seven-membered heterocycle-fused indolizine scaffolds from simple building blocks. Based on our preliminary results, a probable mechanism for this reaction pathway has been proposed.