Catalytic enantioselective acyl transfer: the case for 4-PPY with a C-3 carboxamide peptide auxiliary based on synthesis and modelling studies
作者:Rudy E. Cozett、Gerhard A. Venter、Maheswara Rao Gokada、Roger Hunter
DOI:10.1039/c6ob01991a
日期:——
and evaluated in the kinetic resolution of a small library of chiral benzylic secondary alcohols. A key design element was the incorporation of a tryptophan residue in the peptide side chain for promoting π-stacking between peptide side chain and the pyridiniumring of the N-acyl intermediate, in which modelling was used as a structure-based guiding tool. Together, a catalyst containing a LeuTrp-N-Boc
Designing the “Search Pathway” in the Development of a New Class of Highly Efficient Stereoselective Hydrosilylation Catalysts
作者:Vincent César、Stéphane Bellemin-Laponnaz、Hubert Wadepohl、Lutz H. Gade
DOI:10.1002/chem.200500132
日期:2005.4.22
coupling of oxazolines and N-heterocyclic carbenes leads to chelating C,N ancillary ligands for asymmetric catalysis that combine both an "anchor" unit and a stereodirecting element. Reacting various N-substituted imidazoles with 2-bromo-4(S)-tert-butyl- and 2-bromo-4(S)-isopropyloxazoline gave the imidazolium precursors of the stereodirecting ancillary ligands. A library of ten different ligand precursors
Chiral-at-metal iridium complex for efficient enantioselective transfer hydrogenation of ketones
作者:Cheng Tian、Lei Gong、Eric Meggers
DOI:10.1039/c6cc00972g
日期:——
A bis-cyclometalated iridium(III) complex with metal-centered chirality catalyzes the enantioselectivetransferhydrogenation of ketones with high enantioselectivities at low catalyst loadings down to 0.002 mol%. Importantly, the rate of catalysis...
Synthesis of rhodium(I) and iridium(I) complexes of chiral N-heterocyclic carbenes and their application to asymmetric transfer hydrogenation
作者:Gavin Dyson、Jean-Cédric Frison、Adrian C. Whitwood、Richard E. Douthwaite
DOI:10.1039/b909290k
日期:——
and iridium complexes of chiral NHC–phenolimine and NHC–amine ligands have been prepared and studied for asymmetric transfer hydrogenation. X-ray and NMR spectroscopy show that for NHC–phenolimine complexes abstraction of chloride results in a change in ligand coordination from NHC only to chelating NHC–imine. Complexes of NHC–amines are inactive for transfer hydrogenation, whereas complexes of NHC–phenolimines
Copper-Catalyzed Asymmetric Hydrogenation of Aryl and Heteroaryl Ketones
作者:Scott W. Krabbe、Mark A. Hatcher、Roy K. Bowman、Mark B. Mitchell、Michael S. McClure、Jeffrey S. Johnson
DOI:10.1021/ol4021223
日期:2013.9.6
High throughput screening enabled the development of a Cu-based catalyst system for the asymmetric hydrogenation of prochiral aryl and heteroarylketones that operates at H2 pressures as low as 5 bar. A ligand combination of (R,S)-N-Me-3,5-xylyl-BoPhoz and tris(3,5-xylyl)phosphine provided benzylic alcohols in good yields and enantioselectivities. The electronic and steric characteristics of the ancillary