om6b00290_si_002.cif (122.12 kB)

1,2-Addition or Enolization? Variable Reactivity of a Cerium Acetylide Complex toward Carbonyl Compounds

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posted on 06.06.2016, 17:05 by Jee Eon Kim, Alexander V. Zabula, Patrick J. Carroll, Eric J. Schelter
The reactions of the cerium alkyne complex bearing 2,6-bis­(dimethylamino)-4-methylphenolate supporting ligands (bdmmp) and a terminal acetylide moiety, Na­[Ce­(CCPh)­(bdmmp)3] (1), with benzaldehyde and a family of enolizable ketones led to different products depending on the acidity of the parent carbonyl compound. The reactions of 1 with benzaldehyde, acetone, benzylideneacetone, or 1,1-diphenylacetone (pKaDMSO = 26.5–19.4) gave the products of nucleophilic addition of type Na­[Ce­(O-CR2-CCPh)­(bdmmp)3] featuring a new C–C bond. In contrast, the reaction of 1 with β-tetralone (pKaDMSO = 17.6) resulted in the enolization and deprotonation of β-tetralone with subsequent replacement of the acetylide ligand at the cerium ion by the enolate. Molecular structures for the cerium products were determined by X-ray diffraction studies, providing valuable information about the performance of organocerium reagents.