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
The copper-catalyzed asymmetric hydrosilylation of ketones is an efficient method for the synthesis of chiral enantiopure secondary alcohols. Herein, we present a detailed computational study (DFT/B3LYP) of the copper(I)-catalyzed reaction. In particular, the two transition states involved in the catalytic cycle have been determined. The insertion of the ketone into the Cu-H bond was found to have
Reduction of α,β-Unsaturated Ketones with Diphenylsilanes Bearing Several Substituents on Their Phenyl Moiety Catalyzed by Rhodium–Phosphine Complexes
作者:Daisuke Imao、Miyuki Hayama、Kohta Ishikawa、Tetsuo Ohta、Yoshihiko Ito
DOI:10.1246/cl.2007.366
日期:2007.3.5
1,4-Addition product was afforded exclusively by rhodium-phosphine complex-catalyzed hydrosilylation by using 2-cyclohexen-1-one and a dihydrosilane bearing an ether substituent in spite of the fact that dihydrosilanes were believed to give 1,2-addition product selectively.
feedstock isoprene with unactivated silanes has been developed using earth‐abundant iron catalysts. The manipulation of regioselectivity relies on fine modification of the coordination geometry of the iron center. While a bidentate pyridine imine ligand promoted the formation of allylic silanes through 4,1‐addition, selectivity for the 3,4‐adduct homoallylic silanes was observed with a tridentate nitrogen
Getting up to speed: Both LiCl and the YCl3/MeLi catalyst system have an acceleration effect upon the substitution of silanesusingGrignardreagents (see scheme). The method provides access to benzyl‐, allyl‐, and arylsilanes in good yields from the starting silanes.