Phosphaferrocenes, acylation

Aromatic electrophilic acylations were described only in the coordination sphere of the phospholide anion involving phosphacymantrenes [43, 44] or phosphaferrocenes [45],... 

Bidentate phosphaferrocene-oxazoline 7, generated by acylation with the corresponding phos-phaferrocene trifluoroacetate followed by oxazoline formation, has proved to be a highly efficient ligand for asymmetric induction in the copper-catalyzed conjugate addition of diethylzinc to a, (3-... 

Planar chiral phosphaferrocene-oxazolines (379) constitute another family of complexes that are usefiil as ligands in asymmetric catalysis. Preparation of these takes advantage of a modified Friedel-Crafts acylation of (373) and an unusual conversion of the resulting trifluoromethyl ketone into an amide that is then cyclized to an oxazoline. The diastereomeric complexes thus formed are chromatographically separable and are used in a palladium-catalyzed asymmetric allylic substitution. Modification of this complex by using the anion derived from 3,4-dimethyl-2-phenylphosphole gives more... 

This reaction provides a mild way to decomplex the phosphole ring. The much reduced nucleophilicity of phosphorus consequently does not interfere with the reactions of electrophiles at carbon. It is thus possible to acylate phosphacymantrenes and phosphaferrocenes. Some examples are given below ... 

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