Metal enolato complexes deprotonation

The Af,0-enolato ligands 146 are usually prepared by deprotonation of the corresponding conjugated acids which, for ketimines, can be formulated as consisting of the tautomeric forms 147-149. However, some of them have been prepared (i) by reacting nitriles with the corresponding S-diketonato complexes, or with 2-oxoalkyl or enolato complexes (Section in.C, Chapter 6 ) or (ii) by oxidation of diketoamines with metal complexes in the presence of a base (Section n.B.3). Although the most abundant tautomeric form of a S-ketimine depends on the nature of the substituents, they wiU be represented as 148. 

This method consists in the generation of the enolato hgand by deprotonation of the corresponding carbonyl compound RC(0)CHR R" in the presence of a metal (M) salt or complex. However, frequently the deprotonating agent is a compound of a different metal, M X (M = alkali, alkaline-earth, T1(I), etc., X = amide, hydride, acetate, etc.). In this case, the synthesis of the desired complex is a one-pot, two-step process consisting of [M ]—OC(=CR R")R formation followed by transmetalation of the enolato ligand from [M ] to [M]. 

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