Titanium tartramide complexes catalyst

A very important aspect of this mechanism is not shown in the scheme. This is the formation of the titanium-tartrate species from its commercially available precursors, Ti(0-t-Pr)4 and the dialkyl tartrate. The equilibrium in this step lies far toward the formation of the chiral complex formed this is critical because the enantioselectivity of the process depends on the absence of any active achiral catalyst. Note that the complex as drawn (in the upper left of Scheme 8.5) is dimeric and has a C2 axis of symmetry. This structure has not been isolated in the solid state, but is based in part on an X-ray structure of a related tartramide complex [18]. The situation is undoubtedly complicated by dynamic equilibria between this form and other species in solution. 

The structure of the catalyst has been studied by several spectroscopic methods [813], and it appears that a binuclear titanium complex 3.18 is the predominant species in solution. Tartramides 3.19 have been proposed as substitutes for dialkyl... 

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