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Asymmetric calcium-catalyzed direct Mannich reactions of 1,3-dicarbonylcompounds with imines have been developed. The reactions proceedunder mild conditions and provide the corresponding products withhigh enantiomeric excess.

Effective metal-catalyzed benzylations of 4-hydroxycoumarin have been developed. Employing a low amount of a cheap, nontoxic, and air-stable catalyst the 3-alkylated hydroxycoumarins were isolated in high yields after short reaction times. Applying this new methodology two widely used anticoagulants phenprocoumon and coumatetralyl were synthesized applying mild reaction conditions.

Asymmetric hydrogenations are of great importance in the synthesisof optically active amines. This account highlights the developmentof the first metal-free transfer hydrogenation that is both highlyenantioselective and inspired by nature’s dehydrogen-ase.Further focus is given to the extension of this bioinspired processto provide a variety of valuable, biologically active products andnatural products under mild reaction conditions. 1 Introduction 2 Nature’s Reductions: Dehydrogenases as a Role Model 3 Bronsted Acid catalyzed Transfer Hydrogenation of Ketimines 4 Asymmetric Organocatalytic Reduction of Quinolines 5 Asymmetric Organocatalytic Reduction of N-Heterocycles 5.1 Asymmetric Bronsted Acid Catalyzed Hydrogenationof -Indoles 5.2 Asymmetric Bronsted Acid Catalyzed Hydrogenationof Benzoxazines, Benzthiazines, Benzoxazinones, Quinoxalines, Quinoxalinonesand Benzodiazepinones 6 Asymmetric Organocatalytic Reduction of Pyridines 7 Asymmetric Organocatalytic Reductions in Cascade -Sequences 8 Conclusion

We here describe the development of the first enantioselective Bronsted acid assisted chiral Bronsted acid catalyzed direct Mannich reaction of acetophenone with various aldimines. The reaction proceeds in the presence of a chiral and an achiral Bronsted acid which simultaneously activate the ketone and aldimine to give the corresponding p-amino ketones with good enantioselectivities and without the necessity of enolate preformation.

A new Bronsted acid catalysed hydrogenation of imines with Hantzsch dihydropyridine as the hydrogen source has been developed. Diphenyl phosphate (DPP) and various other acids catalyse this first metal-free hydrogen transfer to give various amines under mild reaction conditions.