Titanium ditriflate Claisen condensation

A potentially valuable example of a crossed Claisen condensation was described by Tanabe and Mu-kaiyama in 1986. It arose from their earlier work on titanium(IV) ditriflate [dichlorobis(trifluorometh-anesulfonato)titanium(IV)] and triethylamine as a catalytic promoter of the simple Claisen reaction. The reaction was run in the presence of benzaldehyde, added to observe the aldol reaction, but the propionate anion added to the carbonyl group of another ester molecule in preference (equation 11). The same result was observed in a Dieckmann reaction dimethyl adipate, TiCh (OTf) (1.5 equiv.) and triethylamine... 

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