Chiral zirconium-catalyzed asymmetric mannich-type reactions using acylhydrazones as imine equivalents

In the presence of a catalytic amount of a new zirconium catalyst, prepared from zirconium(IV) t-butoxide and (R)-3,3'-dibromo-1,1'-bi-2-naphthol, 4-t rifluoromethylbenzoylhydrazones reacted with silyl enolates to afford the c orresponding adducts, beta-N'-acylhydrazinocarbonyl compounds, in good yiel ds with high enantiomeric excesses. Reductive cleavage of the nitrogen-nitr ogen bond of the hydrazino compound using samarium diiodide gave a chiral b eta-aminocarbonyl compound. In addition, the hydrazino compound was also su ccessfully converted to chiral beta-lactam and pyrazolidinone derivatives.