(S)-Serine derived N–O and N–P oxazoline ligands for asymmetric catalysis
作者:Geraint Jones、Christopher J. Richards
DOI:10.1016/j.tetasy.2003.11.030
日期:2004.2
l)oxazoline N–P ligand 19, and an X-raycrystalstructure analysis was obtained of the palladium dichloride adduct. Treatment of 3a–e with Ph2PCl under basic conditions resulted in the corresponding phosphinite–oxazoline N–P ligands 4a–e. All the N–P ligands were screened to determine the most selective for the palladium-catalysed allylic alkylation with dimethyl malonate of the following racemic substrates:
Simple phosphinite–oxazoline ligands for asymmetric catalysis
作者:Geraint Jones、Christopher J Richards
DOI:10.1016/s0040-4039(01)01041-3
日期:2001.8
4-(Hydroxymethyl)oxazolines, derived from (S)-serine methyl ester and a variety of acid chlorides (RCOCl), were reacted with Ph2PCl to give new phosphinite-oxazoline P-N ligands. These mediate the palladium catalysed asymmetric alkylation with dimethyl malonate with the following racemic propenyl substrates (RCH)-C-1=CHCH(OX)R-1: (a) R-1 =Ph, X = Ac-96% e.e.(S) with R=Ph; (b) R-1 = Me, X = CO2' Bu-70% e.e.(S) with R=(eta (5)-C5H4)(eta (4)-C4Ph4)CO. (C) 2001 Published by Elsevier Science Ltd.
Synthesis and Application of ChiralN-Heterocyclic Carbene–Oxazoline Ligands: Iridium-Catalyzed Enantioselective Hydrogenation
作者:Steve Nanchen、Andreas Pfaltz
DOI:10.1002/chem.200501500
日期:2006.6.2
one compound from each family was characterized by X-ray structure analysis. The two libraries of iridium complexes were successfully tested in the asymmetric hydrogenation of unfunctionalized and functionalized olefins. Enantioselectivities of up to 90 % ee were obtained with trans-alpha-methylstilbene. Upon complexation of imidazolium salt 15 p with R(1) = phenyl, C-H bond activation of the phenyl