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Asymmetric synthesis of novel 1,4-aminoalcohol ligands with norbornene and norbornane backbone: use in the asymmetric diethylzinc addition to benzaldehyde

2007-09-27
Tanyeli, Cihangir
Odabas, Serhat
ERDEM, Mine
ÇAKIR, Esen
KESKİN, Eda
The asymmetric synthesis of cis-1,4-aminoalcohols with norbornene and norbornane backbone was performed starting with (2S, 3R)-(-)-cis-hemiester 1 (98% ee). Chemoselective amination with HMPTA followed by Grignard reactions and subsequent LAH reductions afforded compounds 5a-d. cis-Hemiester 1 was also transformed into chiral ligands 7a-f and 9a-d with the DCC coupling method followed by LAH reduction using acyclic, heterocyclic amines and various aniline derivatives and p-toluenesulfonamide, respectively. The chiral ligands were subjected to asymmetric diethylzinc addition to examine their effectiveness as chiral catalysts. Among these, arylamine and tosyl substituted chiral ligands 9a-d exhibited the highest selectivities (up to 97% ee). (c) 2007 Elsevier Ltd. All rights reserved.