Synthesis of novel monodentate phosphoramidites and their application in iridium-catalyzed asymmetric hydrogenations.
New monodentate H(8)-binaphthol based phosphoramidites 6 b-i have been prepared. Starting from (S)-3,3'-dibromo-5,5',6,6',7,7',8,8'-octahydro-1,1'-binaphthyl-2,2'-diol 3, a general protocol for the synthesis of ligands 6 is presented. A small ligand library bearing aryl substituents in the 3,3'-position of the binaphthol core was synthesized and successfully tested in the iridium-catalyzed asymmetric hydrogenation of 2-amidocinnamates to obtain different alpha-amino acid derivatives in up to 99 % ee.
Erre
Giulia
G
Leibniz-Institut für Katalyse e.V. an der Universität Rostock, Albert-Einstein-Strasse 29a, 18059 Rostock, Germany.
Junge
Kathrin
K
Enthaler
Stephan
S
Addis
Daniele
D
Michalik
Dirk
D
Spannenberg
Anke
A
Beller
Matthias
M