2005

2. Enantioselective Brønsted Acid Catalyzed Transfer Hydrogenation:  Organocatalytic Reduction of Imines

Magnus Rueping, Erli Sugiono, Cengiz Azap, Thomas Theissmann, Michael Bolte

Org. Lett. 2005, 7, 3781-3783

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ABSTRACT:

The first enantioselective Brønsted acid catalyzed reduction of imines has been developed. This new organocatalytic transfer hydrogenation of ketimines with Hantzsch dihydropyridine as the hydrogen source offers a mild method to various chiral amines with high enantioselectivity. The stereochemistry of the chiral amines can be rationalized by a stereochemical model derived from an X-ray crystal structure of a chiral BINOL phosphate catalyst.

1. Brønsted Acid Catalysis: Organocatalytic Hydrogenation of Imines

Magnus Rueping, Cengiz Azap, Erli Sugiono, Thomas Theissmann

Synlett 2005, 2367-2369

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ABSTRACT:

A new Brønsted 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.