Tandem asymmetric conjugate addition-enolacetates formation of enantiomerically enriched zinc and aluminium enolates

The metal enolates, resulting from the copper-catalyzed enantioselective conjugate addition of organometallic reagents (Et₂Zn or R₃Al) to cyclic and acyclic enones are quantitatively trapped as enolacetates with acetic anhydride.     

Plasticized open-cell polyurethane foam as a universal matrix for organic reagents in trace element preconcentration: Part I. Collection of silver traces on dithizone foam

The preparation of plasticized foam containing dithizone or zinc dithizonate is described. The foam was used successfully for the rapid and quantitative collection of trace amounts of silver in batch and column experiments. The preconcentration of small amounts of silver from dilute aqueous solutions was found to be possible. The effects of different plasticizers, pH of the aqueous phase, and dithizone concentration in the foam, on the collection rate of silver were critically investigated.