Derivatization of α-aminoacids, α-aminoesters and α-aminolactones as N-acetyl derivatives allow the accurate NMRdetermination of the enantiomericpurity. In these conditions the major coordination site with a chiral shift reagent will correspond to the NMR observation site. Experimental factors leading to the highest ΔΔδ values are ascertained. No straightforward correlation with absolute configurations
作者:Paweł Dydio、Christophe Rubay、Tendai Gadzikwa、Martin Lutz、Joost N. H. Reek
DOI:10.1021/ja208589c
日期:2011.11.2
We report an achiral bisphosphine rhodiumcomplex equipped with a binding site for the recognition of chiral anion guests. Upon binding small chiral guests--cofactors--the rhodiumcomplex becomes chiral and can thus be used for asymmetric catalysis. Screening of a library of cofactors revealed that the best cofactors lead to hydrogenation catalysts that form the products with high enantioselectivity
N-acylaminoacidesters are easily accessible from enamides by cobalt-catalyzed hydroalkoxycarbonylation in moderate to excellent yield. An important reaction parameter for selective carbonylation is the use of low hydrogen partial pressure, which prevents hydrogenation as a side reaction. The reported method is applicable to various enamides and alcohols. A DFT calculation of the catalytic cycle