Tridentate ligands, Mukaiyama aldol reaction

Treatment of tridentate ligand with Ti(0 Pr)4 and di-ferf-butylsalicyclic acid (163) in toluene followed by evaporation of the solvent afforded an orange complex postulated to be 165, which was shown to be an effective catalyst for the Mukaiyama aldol reaction. Under optimized conditions, the simple methyl acetate-derived enol silane 166 adds to aldehydes in the presence of as little as... 

Carreira s recent work is an extension of earlier studies [5] in which a titanium(IV) complex, prepared in situ from tridentate ligand ( )-l and Ti(Ot Pr)4, was found to catalyze Mukaiyama aldol reactions with high enantioselectivities. The chiral ligand used in both the ene and aldol chemistry is prepared from 3-bromo-5-ferf-butylsalicylaldehyde and 2-amino-2 -hydroxy-l,T-binaphthol. This... 

The concept developed for the asymmetric Sn-catalyzed aldol reaction with chiral Ar,AT-ligand by Mukaiyama and co-workers was further extended by Evans and co-workers with bidentate bis(oxazoline) and tridentate pyridylbis(oxazoline) ligands (186). After a survey of ligand architecture, the best level of asymmetric induction was exhibited by [Sn(S,S)-pybox](OTf)2 138 for the Mukaiyamai aldol reaction of substituted silylketene acetal and methyl pyruvate. Noteworthy, the... 

Brookhart et al. [5] have demonsttated that Rh complex (4) with N,N,N-tridentate is an easily synthesized, isolable cationic compotmd that shows remarkable stability for a three coordinate, 14-electron complex and was used as a catalyst for hydrosilylation, Mukaiyama aldol, and cyclopropanation reactions in chlorobenzene to give the corresponding products (Scheme 16.2). As they expected, the Rh complex was found to be a fairly potent Lewis acid, and the steric environment imposed by the ligand created a binding pocket that accommodated potential substrates. 

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