Promotion of a Ti-Mediated Mannich Reaction by a Proton Source.

ABSTRACT

Low temperature NMR studies revealed that a diastereoselective Mannich reaction between a phenyl oxazolidone-derived titanium enolate and an aromatic aldimine was found to occur only after introduction of a proton source. While various protic additives could be used to promote the transformation, the best results were obtained using AcOH to afford the corresponding Mannich products in high diastereoselectivities and yields.