Hydrozirconation across Heteropolar Multiple Bonds

Reduction with [Cp2Zr(H)Cl]n (1) of common C=X functional groups such as aldehydes, ketones, nitriles and related functionality is also possible. 

Carbonyl compounds, such as aldehydes [103, 179], (thio)ketones [31, 94, 180-183], carboxylic acids, and esters [183, 184] with 1 are reduced to alcohols after hydrolysis [5], except in stericaUy hindered cases (see Section 8.5) [185, 186]. Under the same experimental conditions the regioselective reduction of the oxirane ring with 1 gives also the corresponding alcohol [183, 187]. 

Another route for the formation of imines is the treatment of secondary carboxamides with an excess of 1 [196], 

In marked contrast to the other hetero atom multiple bond functions cited in this section the C=N- imine bond was not found to undergo hydrometalation. Imines with neighboring C-H bonds as in PhCH=NMe do react with 1 via imine/enamine tautomerism, but not by hydrozirconation [197]. 

The reaction of 1 with diphenyldiazomethane resulted in the hydrogenation of the C=N=N unit to form the hydrazonato ligand, which is found T -N,N bonded to the metal [198, 199]. 

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