Scheme 41. Bidentatecarboxamide-based auxiliary group-directed total synthesis of Hibispeptin A 119.Scheme 42. g-Arylation of aliphatic acids containing b-quaternary carbons.Scheme43. Ligand-promoted g-arylation of natural amino acid derivatives.

Enantioselective Mannich reactions of pyruvates catalyzed by amine-based catalyst systems, in which pyruvates act as nucleophiles, are reported. The reactions of pyruvates and cyclic sulfonylimines afforded the desired Mannich products, including those bearing tetrasubstituted carbon centers, in high yields with high enantioselectivities in most cases. The selection of the acid used in the amine-based catalyst system was key for the formation of the Mannich products with high enantioselectivities.

Acyl chain transfer, which perturbs the protonation equilibrium of amine and reduces the apparent pKa by 2.0-2.5 units, is used to develop a liposome-based drug delivery system.

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