Iron-catalyzed hydrogen atom transfer induced cyclization of 1,6-enynes for the synthesis of ketoximes: a combined experimental and computational study

Abstract

Described herein is the development of an iron-catalyzed HAT induced radical cyclization hydro-oximation of 1,6-enynes. This transformation involves four step cascade processes: (i) iron-catalyzed hydrogen-atom transfer, (ii) intramolecular radical cyclization of the alkyne, (iii) NO radical capture by the vinyl radical, and (iv) tautomerization of a nitroso alkene to access the ketoximes. Detailed DFT calculations have provided evidence for the transformation processes and the stereoselective formation of ketoximes. Notably, the same strategy has also been applied for the synthesis of pyrrolo[3,2-d]isoxazoles with a quaternary stereocenter via a two-step transformation.