A hypervalent iodine-mediated spirocyclization of 2-(4-hydroxybenzamido)-acrylates - unexpected formation of δ-spirolactones

On the way towards a new total synthesis of (S)-arogenate, a novel aryl-lambda(3)-iodane-mediated oxidative spirocyclization of para-substituted phenol derivatives has been discovered. Starting from easy accessible 2-(4-hydroxybenzamido) acrylates we could construct spirocyclic lactams in up to 52% yield. Under alternative reaction conditions the same precursors underwent an unexpected oxidative spirocyclization yielding a novel delta-spirolactone in up to 70% yield.