Palladium-mediated synthesis of a new eight-membered heterocycle

Abstract

The eight-membered heterocycle 3 has been prepared in 94% isolated yield starting from phenylnorbornylpalladium chloride dimer, o-iodoacetanilide and carbon monoxide in DMF at room temperature. Compound 3 has been unequivocally characterized by X-ray single crystal diffraction. Formation of 3 must involve coordination of the amido group to palladium which prevents ring closure to a hexahydromethanotriphenylene derivative.

Palladium/Norbornene Cooperative Catalysis

“…Using p-nitrobenzyl bromide instead of allyl bromide, Catellani was able to isolate a similar Pd(IV) complex 20, which underwent further reductive elimination to give complex 21. 39 It was proposed that, in such a model reaction, an initial rearrangement of ligands took place to put the aryl and benzyl groups at axial-equatorial, rather than equatorial cis positions (thus avoiding the need for an unlikely N-Pd-N widening), presumably by temporary dissociation of the bromide ligand. The relative stereochemistry of the oxidative addition step was later determined by the Lautens group in a catalytic reaction using an enantioenriched secondary extrude NBE, followed by termination to regenerate either the Pd(0) or Pd(II) catalyst.…”