Umpolung of an Aliphatic Ketone to a Magnesium Ketone-1,2-diide Complex with Vicinal Dianionic Charge

摘要

The new β-diketimine ~(iPrDip)nacnacH,HC-(iPrCNDip)2H,Dip = 2,6-iPr2-C6H3,was converted to the magnesium(I)complex{((~(iPrDip)nacnac)Mg}2and reaction with 2-adamantanone(OAd)afforded the ketone-1,2-diide complex{(~(iPrDip)nacnac)Mg}2(μ-OAd).The complex contains the first stable dianion of an aliphatic ketone with an electropositive metal and shows an OAd2"unit with long C-O bond and pyramidal carbon centre.DFT studies reveal an anionic charge on both neighbouring C and O atoms.Reductions of aliphatic ketones with magnesium(I)complexes show that these likely proceed via highly reactive dianions and afforded a 1:1 mixture of an alkoxide and an enolate when an enolisable ketone was used,and rapid CH activations reactions,e.g.,of stabilising ligand moieties,when non-enolisable ketones were employed.