Cerium(iv) ammonium nitrate mediated 5-endo-dig cyclization of α-amino allenylphosphonates to spirodienones

Abstract

α-Amino allenylphosphonates were treated with cerium(IV) ammonium nitrate under various conditions to form spirodienones in good to excellent yields. The 5-endo-dig cyclization proceeds through the formation of a key iminium intermediate. A comprehensive study on the nature of the solvent used for this reaction was undertaken resulting in the formation of three types of spirodienone scaffolds.